The following output is produced: After delete: This a test After deleteCharAt: his a test in Java

Maker QR-Code in Java The following output is produced: After delete: This a test After deleteCharAt: his a test

replace( )

You can replace one set of characters with another set inside a StringBuffer object by calling replace( ) Its signature is shown here: StringBuffer replace(int startIndex, int endIndex, String str) The substring being replaced is specified by the indexes startIndex and endIndex Thus, the substring at startIndex through endIndex is replaced The replacement string is passed in str 1 The resulting StringBuffer object is returned The following program demonstrates replace( ):

// Demonstrate replace() class replaceDemo { public static void main(String args[]) { StringBuffer sb = new StringBuffer("This is a test");

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sbreplace(5, 7, "was"); Systemoutprintln("After replace: " + sb); } }

substring( )

You can obtain a portion of a StringBuffer by calling substring( ) It has the following two forms: String substring(int startIndex) String substring(int startIndex, int endIndex) The first form returns the substring that starts at startIndex and runs to the end of the invoking StringBuffer object The second form returns the substring that starts at startIndex and runs through endIndex These methods work just like those defined for String that 1 were described earlier

In addition to those methods just described, StringBuffer includes several others They are summarized in the following table Notice that several were added by J2SE 5

Method StringBuffer appendCodePoint(int ch) int codePointAt(int i) int codePointBefore(int i) int codePointCount(int start, int end) int indexOf(String str) int indexOf(String str, int startIndex) Description Appends a Unicode code point to the end of the invoking object A reference to the object is returned Added by J2SE 5 Returns the Unicode code point at the location specified by i Added by J2SE 5 Returns the Unicode code point at the location that precedes that specified by i Added by J2SE 5 Returns the number of code points in the portion of the invoking String that are between start and end 1 Added by J2SE 5 Searches the invoking StringBuffer for the first occurrence of str Returns the index of the match, or 1 if no match is found Searches the invoking StringBuffer for the first occurrence of str, beginning at startIndex Returns the index of the match, or 1 if no match is found Searches the invoking StringBuffer for the last occurrence of str Returns the index of the match, or 1 if no match is found Searches the invoking StringBuffer for the last occurrence of str, beginning at startIndex Returns the index of the match, or 1 if no match is found

int lastIndexOf(String str) int lastIndexOf(String str, int startIndex)

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Method int offsetByCodePoints(int start, int num)

Description Returns the index with the invoking string that is num code points beyond the starting index specified by start Added by J2SE 5 Returns a substring of the invoking string, beginning at startIndex and stopping at stopIndex This method is required by the CharSequence interface, which is now implemented by StringBuffer Reduces the size of the character buffer for the invoking object to exactly fit the current contents Added by J2SE 5

CharSequence subSequence(int startIndex, int stopIndex) void trimToSize( )

Aside from subSequence( ), which implements a method required by the CharSequence interface, the other methods allow a StringBuffer to be searched for an occurrence of a String The following program demonstrates indexOf( ) and lastIndexOf( ):

class IndexOfDemo { public static void main(String args[]) { StringBuffer sb = new StringBuffer("one two one"); int i; i = sbindexOf("one"); Systemoutprintln("First index: " + i); i = sblastIndexOf("one"); Systemoutprintln("Last index: " + i); } }

The output is shown here: First index: 0 Last index: 8

J2SE 5 adds a new string class to Java s already powerful string handling capabilities This new class is called StringBuilder It is identical to StringBuffer except for one important difference: it is not synchronized, which means that it is not thread-safe The advantage of StringBuilder is faster performance However, in cases in which you are using multithreading, you must use StringBuffer rather than StringBuilder