StringBuffer class

Some methods below: .insert(...), .append(...), .getChars(...), setLength(...)

For charAt(...) and indexOf(...), see String’s methods charAt(...) and indexOf(...)

■ A StringBuffer’s default capacity is 16 characters, if not specified otherwise in a constructor. However StringBuffer capacities are automatically increased whenever necessary. If they should overflow they just get automatically made longer.

■ The concatenation + symbol is the same as the append(...) method for StringBuffer. i.e

sb = "a" + "b" + "c"; produces the same abc result as the same as the line below

StringBuffer sb = new StringBuffer( ).append("a").append("b").append("c");

■ StringBuffer does not have an equals( ) method override like String and the wrapper classes do.

So for StringBuffer, == produces the same result as equals( ). Both just look at the object pointer, not at the actual contents.

■ StringBuffer does not have a shorthand form of its constructor, like String does. i.e.

String s = "ABC"; works but

StringBuffer sb = "ABC"; won't compile.

You must say StringBuffer sb = new StringBuffer("ABC");

StringBuffer .insert( offset, type ) method

■ Works for many types, including boolean. It inserts the automatic .valueOf String representation of the second parm into the StringBuffer at the specified offset. The offset starts at zero.

■ It updates the original object’s pointer.

StringBuffer .append( type ) method

■ Works for many types, including boolean. Adds their String representation onto the end of this StringBuffer. It’s like doing an insert(...) at the end.

■ Updates the object pointer.

void .getChars( srcBegin, srcEnd, char[ ] , dstBegin ) method

■ Just like String's similar method. It copies specified chars, from index srcBegin to index SrcEnd-1, copying them into a pre-existing char array starting at index dstBegin.

■ Will throw an IndexOutOfBoundsException if there’s anything wrong with any of the indexes.

■ This snippet copies the a and b from the StringBuffer onto the locations of the 4 and 5 in the original char array, printing the result 1 2 3 a b 6.

StringBuffer sb = new StringBuffer( ).append("a").append("b").append("c");

char[ ] ca = {'1', '2', '3', '4', '5', '6'};

sb.getChars( 0, 2, ca, 3 );

System.out.println(ca);

void .setLength( newlength ) method

■ Resets a StringBuffer's length by either truncating it (if shorter) or padding it with \u0000's (if longer).