StringBuffer Insert and Append
In this chapter you will learn:
- How to append to StringBuffer
- How to use the chained append() method
- How to add data in the middle of a StringBuffer
Append to StringBuffer
The append() method appends the string to the end.
It is overloaded to have the following forms. We can get usage for each method by the parameters.
append(boolean b) is to append boolean value to the StringBuffer.
StringBuffer append(boolean b)StringBuffer append(char c)StringBuffer append(char[] str)StringBuffer append(char[] str, int offset, int len)StringBuffer append(CharSequence s)StringBuffer append(CharSequence s, int start, int end)StringBuffer append(double d)StringBuffer append(float f)StringBuffer append(int i)StringBuffer append(long lng)StringBuffer append(Object obj)StringBuffer append(String str)StringBuffer append(StringBuffer sb)StringBuffer appendCodePoint(int codePoint)
The following code shows how to use the various append methods.
public class Main {
public static void main(String[] argv) {
StringBuffer sb = new StringBuffer();
sb.append(true);//from j a va2s. c o m
sb.append("java2s.com");
sb.append(1.2);
sb.append('a');
System.out.println(sb.toString());
}
}
The output:
String.valueOf( ) is called for each parameter to obtain its string representation.
Chained append() method
The buffer itself is returned by each version of append().
This allows subsequent calls to be chained together, as shown in the following example:
public class Main {
public static void main(String args[]) {
String s;/* ja v a 2 s . c om*/
int a = 42;
StringBuffer sb = new StringBuffer(40);
s = sb.append("a = ").append(a).append("!").toString();
System.out.println(s);
}
}
The output of this example is shown here:
Insert to a StringBuffer
The insert( ) method inserts one string into another.
It is overloaded to accept values of all the simple types, plus Strings, Objects, and CharSequences.
It calls String.valueOf( ) to obtain the string representation of the value it is called with.
StringBuffer insert(int offset, boolean b)StringBuffer insert(int offset, char c)StringBuffer insert(int offset, char[] str)StringBuffer insert(int index, char[] str, int offset, int len)StringBuffer insert(int dstOffset, CharSequence s)StringBuffer insert(int dstOffset, CharSequence s, int start, int end)StringBuffer insert(int offset, double d)StringBuffer insert(int offset, float f)StringBuffer insert(int offset, int i)StringBuffer insert(int offset, long l)StringBuffer insert(int offset, Object obj)StringBuffer insert(int offset, String str)
The following sample program inserts strings:
public class Main {
public static void main(String[] argv) {
StringBuffer sb = new StringBuffer();
sb.append(true);/*from j ava 2s. c o m*/
sb.append("java2s.com");
sb.append(1.2);
sb.append('a');
sb.insert(3,"JAVA@S.COM");
System.out.println(sb.toString());
}
}
The output:
Next chapter...
What you will learn in the next chapter:
- What is difference between length and capacity of a Java StringBuffer
- How to Pre-allocate space
- How to shorten a StringBuffer