- All Implemented Interfaces:
Serializable,Appendable,CharSequence,Comparable<StringBuilder>
StringBuffer, but with no guarantee of synchronization.
This class is designed for use as a drop-in replacement for
StringBuffer in places where the string buffer was being
used by a single thread (as is generally the case). Where possible,
it is recommended that this class be used in preference to
StringBuffer as it will be faster under most implementations.
The principal operations on a StringBuilder are the
append and insert methods, which are
overloaded so as to accept data of any type. Each effectively
converts a given datum to a string and then appends or inserts the
characters of that string to the string builder. The
append method always adds these characters at the end
of the builder; the insert method adds the characters at
a specified point.
For example, if z refers to a string builder object
whose current contents are "start", then
the method call z.append("le") would cause the string
builder to contain "startle", whereas
z.insert(4, "le") would alter the string builder to
contain "starlet".
In general, if sb refers to an instance of a StringBuilder,
then sb.append(x) has the same effect as
sb.insert(sb.length(), x).
Every string builder has a capacity. As long as the length of the character sequence contained in the string builder does not exceed the capacity, it is not necessary to allocate a new internal buffer. If the internal buffer overflows, it is automatically made larger.
Instances of StringBuilder are not safe for
use by multiple threads. If such synchronization is required then it is
recommended that StringBuffer be used.
Unless otherwise noted, passing a null argument to a constructor
or method in this class will cause a NullPointerException to be
thrown.
- API Note:
StringBuilderimplementsComparablebut does not overrideequals. Thus, the natural ordering ofStringBuilderis inconsistent with equals. Care should be exercised ifStringBuilderobjects are used as keys in aSortedMapor elements in aSortedSet. SeeComparable,SortedMap, orSortedSetfor more information.- Since:
- 1.5
- See Also:
-
Constructor Summary
ConstructorsConstructorDescriptionConstructs a string builder with no characters in it and an initial capacity of 16 characters.StringBuilder(int capacity) Constructs a string builder with no characters in it and an initial capacity specified by thecapacityargument.Constructs a string builder that contains the same characters as the specifiedCharSequence.StringBuilder(String str) Constructs a string builder initialized to the contents of the specified string. -
Method Summary
Modifier and TypeMethodDescriptionappend(boolean b) Appends the string representation of thebooleanargument to the sequence.append(char c) Appends the string representation of thecharargument to this sequence.append(char[] str) Appends the string representation of thechararray argument to this sequence.append(char[] str, int offset, int len) Appends the string representation of a subarray of thechararray argument to this sequence.append(double d) Appends the string representation of thedoubleargument to this sequence.append(float f) Appends the string representation of thefloatargument to this sequence.append(int i) Appends the string representation of theintargument to this sequence.append(long lng) Appends the string representation of thelongargument to this sequence.Appends the specified character sequence to thisAppendable.append(CharSequence s, int start, int end) Appends a subsequence of the specifiedCharSequenceto this sequence.Appends the string representation of theObjectargument.Appends the specified string to this character sequence.append(StringBuffer sb) Appends the specifiedStringBufferto this sequence.appendCodePoint(int codePoint) Appends the string representation of thecodePointargument to this sequence.intcapacity()Returns the current capacity.charcharAt(int index) Returns thecharvalue in this sequence at the specified index.chars()Returns a stream ofintzero-extending thecharvalues from this sequence.intcodePointAt(int index) Returns the character (Unicode code point) at the specified index.intcodePointBefore(int index) Returns the character (Unicode code point) before the specified index.intcodePointCount(int beginIndex, int endIndex) Returns the number of Unicode code points in the specified text range of this sequence.Returns a stream of code point values from this sequence.intcompareTo(StringBuilder another) Compares twoStringBuilderinstances lexicographically.delete(int start, int end) Removes the characters in a substring of this sequence.deleteCharAt(int index) Removes thecharat the specified position in this sequence.voidensureCapacity(int minimumCapacity) Ensures that the capacity is at least equal to the specified minimum.voidgetChars(int srcBegin, int srcEnd, char[] dst, int dstBegin) Characters are copied from this sequence into the destination character arraydst.intReturns the index within this string of the first occurrence of the specified substring.intReturns the index within this string of the first occurrence of the specified substring, starting at the specified index.insert(int offset, boolean b) Inserts the string representation of thebooleanargument into this sequence.insert(int offset, char c) Inserts the string representation of thecharargument into this sequence.insert(int offset, char[] str) Inserts the string representation of thechararray argument into this sequence.insert(int index, char[] str, int offset, int len) Inserts the string representation of a subarray of thestrarray argument into this sequence.insert(int offset, double d) Inserts the string representation of thedoubleargument into this sequence.insert(int offset, float f) Inserts the string representation of thefloatargument into this sequence.insert(int offset, int i) Inserts the string representation of the secondintargument into this sequence.insert(int offset, long l) Inserts the string representation of thelongargument into this sequence.insert(int dstOffset, CharSequence s) Inserts the specifiedCharSequenceinto this sequence.insert(int dstOffset, CharSequence s, int start, int end) Inserts a subsequence of the specifiedCharSequenceinto this sequence.Inserts the string representation of theObjectargument into this character sequence.Inserts the string into this character sequence.intlastIndexOf(String str) Returns the index within this string of the last occurrence of the specified substring.intlastIndexOf(String str, int fromIndex) Returns the index within this string of the last occurrence of the specified substring, searching backward starting at the specified index.intlength()Returns the length (character count).intoffsetByCodePoints(int index, int codePointOffset) Returns the index within this sequence that is offset from the givenindexbycodePointOffsetcode points.Replaces the characters in a substring of this sequence with characters in the specifiedString.reverse()Causes this character sequence to be replaced by the reverse of the sequence.voidsetCharAt(int index, char ch) The character at the specified index is set toch.voidsetLength(int newLength) Sets the length of the character sequence.subSequence(int start, int end) Returns a new character sequence that is a subsequence of this sequence.substring(int start) Returns a newStringthat contains a subsequence of characters currently contained in this character sequence.substring(int start, int end) Returns a newStringthat contains a subsequence of characters currently contained in this sequence.toString()Returns a string representing the data in this sequence.voidAttempts to reduce storage used for the character sequence.Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, waitMethods declared in interface java.lang.CharSequence
charAt, chars, codePoints, isEmpty, length, subSequence
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Constructor Details
-
StringBuilder
public StringBuilder()Constructs a string builder with no characters in it and an initial capacity of 16 characters. -
StringBuilder
public StringBuilder(int capacity) Constructs a string builder with no characters in it and an initial capacity specified by thecapacityargument.- Parameters:
capacity- the initial capacity.- Throws:
NegativeArraySizeException- if thecapacityargument is less than0.
-
StringBuilder
Constructs a string builder initialized to the contents of the specified string. The initial capacity of the string builder is16plus the length of the string argument.- Parameters:
str- the initial contents of the buffer.
-
StringBuilder
Constructs a string builder that contains the same characters as the specifiedCharSequence. The initial capacity of the string builder is16plus the length of theCharSequenceargument.- Parameters:
seq- the sequence to copy.
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-
Method Details
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compareTo
Compares twoStringBuilderinstances lexicographically. This method follows the same rules for lexicographical comparison as defined in the CharSequence.compare(this, another) method.For finer-grained, locale-sensitive String comparison, refer to
Collator.- Specified by:
compareToin interfaceComparable<StringBuilder>- Parameters:
another- theStringBuilderto be compared with- Returns:
- the value
0if thisStringBuildercontains the same character sequence as that of the argumentStringBuilder; a negative integer if thisStringBuilderis lexicographically less than theStringBuilderargument; or a positive integer if thisStringBuilderis lexicographically greater than theStringBuilderargument. - Since:
- 11
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append
Appends the string representation of theObjectargument.The overall effect is exactly as if the argument were converted to a string by the method
String.valueOf(Object), and the characters of that string were thenappendedto this character sequence.- Parameters:
obj- anObject.- Returns:
- a reference to this object.
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append
Appends the specified string to this character sequence.The characters of the
Stringargument are appended, in order, increasing the length of this sequence by the length of the argument. Ifstrisnull, then the four characters"null"are appended.Let n be the length of this character sequence just prior to execution of the
appendmethod. Then the character at index k in the new character sequence is equal to the character at index k in the old character sequence, if k is less than n; otherwise, it is equal to the character at index k-n in the argumentstr.- Parameters:
str- a string.- Returns:
- a reference to this object.
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append
Appends the specifiedStringBufferto this sequence.The characters of the
StringBufferargument are appended, in order, to this sequence, increasing the length of this sequence by the length of the argument. Ifsbisnull, then the four characters"null"are appended to this sequence.Let n be the length of this character sequence just prior to execution of the
appendmethod. Then the character at index k in the new character sequence is equal to the character at index k in the old character sequence, if k is less than n; otherwise, it is equal to the character at index k-n in the argumentsb.- Parameters:
sb- theStringBufferto append.- Returns:
- a reference to this object.
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append
Description copied from interface:AppendableAppends the specified character sequence to thisAppendable.Depending on which class implements the character sequence
csq, the entire sequence may not be appended. For instance, ifcsqis aCharBufferthen the subsequence to append is defined by the buffer's position and limit.- Specified by:
appendin interfaceAppendable- Parameters:
s- The character sequence to append. Ifcsqisnull, then the four characters"null"are appended to this Appendable.- Returns:
- A reference to this
Appendable
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append
Appends a subsequence of the specifiedCharSequenceto this sequence.Characters of the argument
s, starting at indexstart, are appended, in order, to the contents of this sequence up to the (exclusive) indexend. The length of this sequence is increased by the value ofend - start.Let n be the length of this character sequence just prior to execution of the
appendmethod. Then the character at index k in this character sequence becomes equal to the character at index k in this sequence, if k is less than n; otherwise, it is equal to the character at index k+start-n in the arguments.If
sisnull, then this method appends characters as if the s parameter was a sequence containing the four characters"null".- Specified by:
appendin interfaceAppendable- Parameters:
s- the sequence to append.start- the starting index of the subsequence to be appended.end- the end index of the subsequence to be appended.- Returns:
- a reference to this object.
- Throws:
IndexOutOfBoundsException- ifstartis negative, orstartis greater thanendorendis greater thans.length()
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append
Appends the string representation of thechararray argument to this sequence.The characters of the array argument are appended, in order, to the contents of this sequence. The length of this sequence increases by the length of the argument.
The overall effect is exactly as if the argument were converted to a string by the method
String.valueOf(char[]), and the characters of that string were thenappendedto this character sequence.- Parameters:
str- the characters to be appended.- Returns:
- a reference to this object.
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append
Appends the string representation of a subarray of thechararray argument to this sequence.Characters of the
chararraystr, starting at indexoffset, are appended, in order, to the contents of this sequence. The length of this sequence increases by the value oflen.The overall effect is exactly as if the arguments were converted to a string by the method
String.valueOf(char[],int,int), and the characters of that string were thenappendedto this character sequence.- Parameters:
str- the characters to be appended.offset- the index of the firstcharto append.len- the number ofchars to append.- Returns:
- a reference to this object.
- Throws:
IndexOutOfBoundsException- ifoffset < 0orlen < 0oroffset+len > str.length
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append
Appends the string representation of thebooleanargument to the sequence.The overall effect is exactly as if the argument were converted to a string by the method
String.valueOf(boolean), and the characters of that string were thenappendedto this character sequence.- Parameters:
b- aboolean.- Returns:
- a reference to this object.
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append
Appends the string representation of thecharargument to this sequence.The argument is appended to the contents of this sequence. The length of this sequence increases by
1.The overall effect is exactly as if the argument were converted to a string by the method
String.valueOf(char), and the character in that string were thenappendedto this character sequence.- Specified by:
appendin interfaceAppendable- Parameters:
c- achar.- Returns:
- a reference to this object.
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append
Appends the string representation of theintargument to this sequence.The overall effect is exactly as if the argument were converted to a string by the method
String.valueOf(int), and the characters of that string were thenappendedto this character sequence.- Parameters:
i- anint.- Returns:
- a reference to this object.
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append
Appends the string representation of thelongargument to this sequence.The overall effect is exactly as if the argument were converted to a string by the method
String.valueOf(long), and the characters of that string were thenappendedto this character sequence.- Parameters:
lng- along.- Returns:
- a reference to this object.
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append
Appends the string representation of thefloatargument to this sequence.The overall effect is exactly as if the argument were converted to a string by the method
String.valueOf(float), and the characters of that string were thenappendedto this character sequence.- Parameters:
f- afloat.- Returns:
- a reference to this object.
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append
Appends the string representation of thedoubleargument to this sequence.The overall effect is exactly as if the argument were converted to a string by the method
String.valueOf(double), and the characters of that string were thenappendedto this character sequence.- Parameters:
d- adouble.- Returns:
- a reference to this object.
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appendCodePoint
Appends the string representation of thecodePointargument to this sequence.The argument is appended to the contents of this sequence. The length of this sequence increases by
Character.charCount(codePoint).The overall effect is exactly as if the argument were converted to a
chararray by the methodCharacter.toChars(int)and the character in that array were thenappendedto this character sequence.- Parameters:
codePoint- a Unicode code point- Returns:
- a reference to this object.
- Since:
- 1.5
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delete
Removes the characters in a substring of this sequence. The substring begins at the specifiedstartand extends to the character at indexend - 1or to the end of the sequence if no such character exists. Ifstartis equal toend, no changes are made.- Parameters:
start- The beginning index, inclusive.end- The ending index, exclusive.- Returns:
- This object.
- Throws:
StringIndexOutOfBoundsException- ifstartis negative, greater thanlength(), or greater thanend.
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deleteCharAt
Removes thecharat the specified position in this sequence. This sequence is shortened by onechar.Note: If the character at the given index is a supplementary character, this method does not remove the entire character. If correct handling of supplementary characters is required, determine the number of
chars to remove by callingCharacter.charCount(thisSequence.codePointAt(index)), wherethisSequenceis this sequence.- Parameters:
index- Index ofcharto remove- Returns:
- This object.
- Throws:
StringIndexOutOfBoundsException- if theindexis negative or greater than or equal tolength().
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replace
Replaces the characters in a substring of this sequence with characters in the specifiedString. The substring begins at the specifiedstartand extends to the character at indexend - 1or to the end of the sequence if no such character exists. First the characters in the substring are removed and then the specifiedStringis inserted atstart. (This sequence will be lengthened to accommodate the specified String if necessary.)- Parameters:
start- The beginning index, inclusive.end- The ending index, exclusive.str- String that will replace previous contents.- Returns:
- This object.
- Throws:
StringIndexOutOfBoundsException- ifstartis negative, greater thanlength(), or greater thanend.
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insert
Inserts the string representation of a subarray of thestrarray argument into this sequence. The subarray begins at the specifiedoffsetand extendslenchars. The characters of the subarray are inserted into this sequence at the position indicated byindex. The length of this sequence increases bylenchars.- Parameters:
index- position at which to insert subarray.str- Achararray.offset- the index of the firstcharin subarray to be inserted.len- the number ofchars in the subarray to be inserted.- Returns:
- This object
- Throws:
StringIndexOutOfBoundsException- ifindexis negative or greater thanlength(), oroffsetorlenare negative, or(offset+len)is greater thanstr.length.
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insert
Inserts the string representation of theObjectargument into this character sequence.The overall effect is exactly as if the second argument were converted to a string by the method
String.valueOf(Object), and the characters of that string were theninsertedinto this character sequence at the indicated offset.The
offsetargument must be greater than or equal to0, and less than or equal to the length of this sequence.- Parameters:
offset- the offset.obj- anObject.- Returns:
- a reference to this object.
- Throws:
StringIndexOutOfBoundsException- if the offset is invalid.
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insert
Inserts the string into this character sequence.The characters of the
Stringargument are inserted, in order, into this sequence at the indicated offset, moving up any characters originally above that position and increasing the length of this sequence by the length of the argument. Ifstrisnull, then the four characters"null"are inserted into this sequence.The character at index k in the new character sequence is equal to:
- the character at index k in the old character sequence, if
k is less than
offset - the character at index k
-offsetin the argumentstr, if k is not less thanoffsetbut is less thanoffset+str.length() - the character at index k
-str.length()in the old character sequence, if k is not less thanoffset+str.length()
The
offsetargument must be greater than or equal to0, and less than or equal to the length of this sequence.- Parameters:
offset- the offset.str- a string.- Returns:
- a reference to this object.
- Throws:
StringIndexOutOfBoundsException- if the offset is invalid.
- the character at index k in the old character sequence, if
k is less than
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insert
Inserts the string representation of thechararray argument into this sequence.The characters of the array argument are inserted into the contents of this sequence at the position indicated by
offset. The length of this sequence increases by the length of the argument.The overall effect is exactly as if the second argument were converted to a string by the method
String.valueOf(char[]), and the characters of that string were theninsertedinto this character sequence at the indicated offset.The
offsetargument must be greater than or equal to0, and less than or equal to the length of this sequence.- Parameters:
offset- the offset.str- a character array.- Returns:
- a reference to this object.
- Throws:
StringIndexOutOfBoundsException- if the offset is invalid.
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insert
Inserts the specifiedCharSequenceinto this sequence.The characters of the
CharSequenceargument are inserted, in order, into this sequence at the indicated offset, moving up any characters originally above that position and increasing the length of this sequence by the length of the argument s.The result of this method is exactly the same as if it were an invocation of this object's
insert(dstOffset, s, 0, s.length()) method.If
sisnull, then the four characters"null"are inserted into this sequence.- Parameters:
dstOffset- the offset.s- the sequence to be inserted- Returns:
- a reference to this object.
- Throws:
IndexOutOfBoundsException- if the offset is invalid.
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insert
Inserts a subsequence of the specifiedCharSequenceinto this sequence.The subsequence of the argument
sspecified bystartandendare inserted, in order, into this sequence at the specified destination offset, moving up any characters originally above that position. The length of this sequence is increased byend - start.The character at index k in this sequence becomes equal to:
- the character at index k in this sequence, if
k is less than
dstOffset - the character at index k
+start-dstOffsetin the arguments, if k is greater than or equal todstOffsetbut is less thandstOffset+end-start - the character at index k
-(end-start)in this sequence, if k is greater than or equal todstOffset+end-start
The
dstOffsetargument must be greater than or equal to0, and less than or equal to the length of this sequence.The start argument must be nonnegative, and not greater than
end.The end argument must be greater than or equal to
start, and less than or equal to the length of s.If
sisnull, then this method inserts characters as if the s parameter was a sequence containing the four characters"null".- Parameters:
dstOffset- the offset in this sequence.s- the sequence to be inserted.start- the starting index of the subsequence to be inserted.end- the end index of the subsequence to be inserted.- Returns:
- a reference to this object.
- Throws:
IndexOutOfBoundsException- ifdstOffsetis negative or greater thanthis.length(), orstartorendare negative, orstartis greater thanendorendis greater thans.length()
- the character at index k in this sequence, if
k is less than
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insert
Inserts the string representation of thebooleanargument into this sequence.The overall effect is exactly as if the second argument were converted to a string by the method
String.valueOf(boolean), and the characters of that string were theninsertedinto this character sequence at the indicated offset.The
offsetargument must be greater than or equal to0, and less than or equal to the length of this sequence.- Parameters:
offset- the offset.b- aboolean.- Returns:
- a reference to this object.
- Throws:
StringIndexOutOfBoundsException- if the offset is invalid.
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insert
Inserts the string representation of thecharargument into this sequence.The overall effect is exactly as if the second argument were converted to a string by the method
String.valueOf(char), and the character in that string were theninsertedinto this character sequence at the indicated offset.The
offsetargument must be greater than or equal to0, and less than or equal to the length of this sequence.- Parameters:
offset- the offset.c- achar.- Returns:
- a reference to this object.
- Throws:
IndexOutOfBoundsException- if the offset is invalid.
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insert
Inserts the string representation of the secondintargument into this sequence.The overall effect is exactly as if the second argument were converted to a string by the method
String.valueOf(int), and the characters of that string were theninsertedinto this character sequence at the indicated offset.The
offsetargument must be greater than or equal to0, and less than or equal to the length of this sequence.- Parameters:
offset- the offset.i- anint.- Returns:
- a reference to this object.
- Throws:
StringIndexOutOfBoundsException- if the offset is invalid.
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insert
Inserts the string representation of thelongargument into this sequence.The overall effect is exactly as if the second argument were converted to a string by the method
String.valueOf(long), and the characters of that string were theninsertedinto this character sequence at the indicated offset.The
offsetargument must be greater than or equal to0, and less than or equal to the length of this sequence.- Parameters:
offset- the offset.l- along.- Returns:
- a reference to this object.
- Throws:
StringIndexOutOfBoundsException- if the offset is invalid.
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insert
Inserts the string representation of thefloatargument into this sequence.The overall effect is exactly as if the second argument were converted to a string by the method
String.valueOf(float), and the characters of that string were theninsertedinto this character sequence at the indicated offset.The
offsetargument must be greater than or equal to0, and less than or equal to the length of this sequence.- Parameters:
offset- the offset.f- afloat.- Returns:
- a reference to this object.
- Throws:
StringIndexOutOfBoundsException- if the offset is invalid.
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insert
Inserts the string representation of thedoubleargument into this sequence.The overall effect is exactly as if the second argument were converted to a string by the method
String.valueOf(double), and the characters of that string were theninsertedinto this character sequence at the indicated offset.The
offsetargument must be greater than or equal to0, and less than or equal to the length of this sequence.- Parameters:
offset- the offset.d- adouble.- Returns:
- a reference to this object.
- Throws:
StringIndexOutOfBoundsException- if the offset is invalid.
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indexOf
Returns the index within this string of the first occurrence of the specified substring.The returned index is the smallest value
kfor which:
If no such value ofthis.toString().startsWith(str, k)kexists, then-1is returned.- Parameters:
str- the substring to search for.- Returns:
- the index of the first occurrence of the specified substring,
or
-1if there is no such occurrence.
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indexOf
Returns the index within this string of the first occurrence of the specified substring, starting at the specified index.The returned index is the smallest value
kfor which:
If no such value ofk >= Math.min(fromIndex, this.length()) && this.toString().startsWith(str, k)kexists, then-1is returned.- Parameters:
str- the substring to search for.fromIndex- the index from which to start the search.- Returns:
- the index of the first occurrence of the specified substring,
starting at the specified index,
or
-1if there is no such occurrence.
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lastIndexOf
Returns the index within this string of the last occurrence of the specified substring. The last occurrence of the empty string "" is considered to occur at the index valuethis.length().The returned index is the largest value
kfor which:
If no such value ofthis.toString().startsWith(str, k)kexists, then-1is returned.- Parameters:
str- the substring to search for.- Returns:
- the index of the last occurrence of the specified substring,
or
-1if there is no such occurrence.
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lastIndexOf
Returns the index within this string of the last occurrence of the specified substring, searching backward starting at the specified index.The returned index is the largest value
kfor which:
If no such value ofk <= Math.min(fromIndex, this.length()) && this.toString().startsWith(str, k)kexists, then-1is returned.- Parameters:
str- the substring to search for.fromIndex- the index to start the search from.- Returns:
- the index of the last occurrence of the specified substring,
searching backward from the specified index,
or
-1if there is no such occurrence.
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reverse
Causes this character sequence to be replaced by the reverse of the sequence. If there are any surrogate pairs included in the sequence, these are treated as single characters for the reverse operation. Thus, the order of the high-low surrogates is never reversed. Let n be the character length of this character sequence (not the length incharvalues) just prior to execution of thereversemethod. Then the character at index k in the new character sequence is equal to the character at index n-k-1 in the old character sequence.Note that the reverse operation may result in producing surrogate pairs that were unpaired low-surrogates and high-surrogates before the operation. For example, reversing "\uDC00\uD800" produces "\uD800\uDC00" which is a valid surrogate pair.
- Returns:
- a reference to this object.
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toString
Returns a string representing the data in this sequence. A newStringobject is allocated and initialized to contain the character sequence currently represented by this object. ThisStringis then returned. Subsequent changes to this sequence do not affect the contents of theString.- Specified by:
toStringin interfaceCharSequence- Returns:
- a string representation of this sequence of characters.
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length
public int length()Returns the length (character count).- Specified by:
lengthin interfaceCharSequence- Returns:
- the length of the sequence of characters currently represented by this object
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capacity
public int capacity()Returns the current capacity. The capacity is the number of characters that can be stored (including already written characters), beyond which an allocation will occur.- Returns:
- the current capacity
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ensureCapacity
public void ensureCapacity(int minimumCapacity) Ensures that the capacity is at least equal to the specified minimum. If the current capacity is less than the argument, then a new internal array is allocated with greater capacity. The new capacity is the larger of:- The
minimumCapacityargument. - Twice the old capacity, plus
2.
minimumCapacityargument is nonpositive, this method takes no action and simply returns. Note that subsequent operations on this object can reduce the actual capacity below that requested here.- Parameters:
minimumCapacity- the minimum desired capacity.
- The
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trimToSize
public void trimToSize()Attempts to reduce storage used for the character sequence. If the buffer is larger than necessary to hold its current sequence of characters, then it may be resized to become more space efficient. Calling this method may, but is not required to, affect the value returned by a subsequent call to thecapacity()method. -
setLength
public void setLength(int newLength) Sets the length of the character sequence. The sequence is changed to a new character sequence whose length is specified by the argument. For every nonnegative index k less thannewLength, the character at index k in the new character sequence is the same as the character at index k in the old sequence if k is less than the length of the old character sequence; otherwise, it is the null character'\u0000'. In other words, if thenewLengthargument is less than the current length, the length is changed to the specified length.If the
newLengthargument is greater than or equal to the current length, sufficient null characters ('\u0000') are appended so that length becomes thenewLengthargument.The
newLengthargument must be greater than or equal to0.- Parameters:
newLength- the new length- Throws:
IndexOutOfBoundsException- if thenewLengthargument is negative.
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charAt
public char charAt(int index) Returns thecharvalue in this sequence at the specified index. The firstcharvalue is at index0, the next at index1, and so on, as in array indexing.The index argument must be greater than or equal to
0, and less than the length of this sequence.If the
charvalue specified by the index is a surrogate, the surrogate value is returned.- Specified by:
charAtin interfaceCharSequence- Parameters:
index- the index of the desiredcharvalue.- Returns:
- the
charvalue at the specified index. - Throws:
IndexOutOfBoundsException- ifindexis negative or greater than or equal tolength().
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codePointAt
public int codePointAt(int index) Returns the character (Unicode code point) at the specified index. The index refers tocharvalues (Unicode code units) and ranges from0toCharSequence.length()- 1.If the
charvalue specified at the given index is in the high-surrogate range, the following index is less than the length of this sequence, and thecharvalue at the following index is in the low-surrogate range, then the supplementary code point corresponding to this surrogate pair is returned. Otherwise, thecharvalue at the given index is returned.- Parameters:
index- the index to thecharvalues- Returns:
- the code point value of the character at the
index - Throws:
IndexOutOfBoundsException- if theindexargument is negative or not less than the length of this sequence.
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codePointBefore
public int codePointBefore(int index) Returns the character (Unicode code point) before the specified index. The index refers tocharvalues (Unicode code units) and ranges from1toCharSequence.length().If the
charvalue at(index - 1)is in the low-surrogate range,(index - 2)is not negative, and thecharvalue at(index - 2)is in the high-surrogate range, then the supplementary code point value of the surrogate pair is returned. If thecharvalue atindex - 1is an unpaired low-surrogate or a high-surrogate, the surrogate value is returned.- Parameters:
index- the index following the code point that should be returned- Returns:
- the Unicode code point value before the given index.
- Throws:
IndexOutOfBoundsException- if theindexargument is less than 1 or greater than the length of this sequence.
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codePointCount
public int codePointCount(int beginIndex, int endIndex) Returns the number of Unicode code points in the specified text range of this sequence. The text range begins at the specifiedbeginIndexand extends to thecharat indexendIndex - 1. Thus the length (inchars) of the text range isendIndex-beginIndex. Unpaired surrogates within this sequence count as one code point each.- Parameters:
beginIndex- the index to the firstcharof the text range.endIndex- the index after the lastcharof the text range.- Returns:
- the number of Unicode code points in the specified text range
- Throws:
IndexOutOfBoundsException- if thebeginIndexis negative, orendIndexis larger than the length of this sequence, orbeginIndexis larger thanendIndex.
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offsetByCodePoints
public int offsetByCodePoints(int index, int codePointOffset) Returns the index within this sequence that is offset from the givenindexbycodePointOffsetcode points. Unpaired surrogates within the text range given byindexandcodePointOffsetcount as one code point each.- Parameters:
index- the index to be offsetcodePointOffset- the offset in code points- Returns:
- the index within this sequence
- Throws:
IndexOutOfBoundsException- ifindexis negative or larger then the length of this sequence, or ifcodePointOffsetis positive and the subsequence starting withindexhas fewer thancodePointOffsetcode points, or ifcodePointOffsetis negative and the subsequence beforeindexhas fewer than the absolute value ofcodePointOffsetcode points.
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getChars
public void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin) Characters are copied from this sequence into the destination character arraydst. The first character to be copied is at indexsrcBegin; the last character to be copied is at indexsrcEnd-1. The total number of characters to be copied issrcEnd-srcBegin. The characters are copied into the subarray ofdststarting at indexdstBeginand ending at index:dstbegin + (srcEnd-srcBegin) - 1- Parameters:
srcBegin- start copying at this offset.srcEnd- stop copying at this offset.dst- the array to copy the data into.dstBegin- offset intodst.- Throws:
IndexOutOfBoundsException- if any of the following is true:srcBeginis negativedstBeginis negative- the
srcBeginargument is greater than thesrcEndargument. srcEndis greater thanthis.length().dstBegin+srcEnd-srcBeginis greater thandst.length
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setCharAt
public void setCharAt(int index, char ch) The character at the specified index is set toch. This sequence is altered to represent a new character sequence that is identical to the old character sequence, except that it contains the characterchat positionindex.The index argument must be greater than or equal to
0, and less than the length of this sequence.- Parameters:
index- the index of the character to modify.ch- the new character.- Throws:
IndexOutOfBoundsException- ifindexis negative or greater than or equal tolength().
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substring
Returns a newStringthat contains a subsequence of characters currently contained in this character sequence. The substring begins at the specified index and extends to the end of this sequence.- Parameters:
start- The beginning index, inclusive.- Returns:
- The new string.
- Throws:
StringIndexOutOfBoundsException- ifstartis less than zero, or greater than the length of this object.
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subSequence
Returns a new character sequence that is a subsequence of this sequence.An invocation of this method of the form
behaves in exactly the same way as the invocationsb.subSequence(begin, end)
This method is provided so that this class can implement thesb.substring(begin, end)CharSequenceinterface.- Specified by:
subSequencein interfaceCharSequence- Parameters:
start- the start index, inclusive.end- the end index, exclusive.- Returns:
- the specified subsequence.
- Throws:
IndexOutOfBoundsException- ifstartorendare negative, ifendis greater thanlength(), or ifstartis greater thanend
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substring
Returns a newStringthat contains a subsequence of characters currently contained in this sequence. The substring begins at the specifiedstartand extends to the character at indexend - 1.- Parameters:
start- The beginning index, inclusive.end- The ending index, exclusive.- Returns:
- The new string.
- Throws:
StringIndexOutOfBoundsException- ifstartorendare negative or greater thanlength(), orstartis greater thanend.
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chars
Returns a stream ofintzero-extending thecharvalues from this sequence. Any char which maps to a surrogate code point is passed through uninterpreted.The stream binds to this sequence when the terminal stream operation commences (specifically, for mutable sequences the spliterator for the stream is late-binding). If the sequence is modified during that operation then the result is undefined.
- Specified by:
charsin interfaceCharSequence- Returns:
- an IntStream of char values from this sequence
- Since:
- 9
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codePoints
Returns a stream of code point values from this sequence. Any surrogate pairs encountered in the sequence are combined as if by Character.toCodePoint and the result is passed to the stream. Any other code units, including ordinary BMP characters, unpaired surrogates, and undefined code units, are zero-extended tointvalues which are then passed to the stream.The stream binds to this sequence when the terminal stream operation commences (specifically, for mutable sequences the spliterator for the stream is late-binding). If the sequence is modified during that operation then the result is undefined.
- Specified by:
codePointsin interfaceCharSequence- Returns:
- an IntStream of Unicode code points from this sequence
- Since:
- 9
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