Monday, 1 October 2012

What is Concatenation in JAVA?

Concatenation describes the operation of joining two strings together. In Java, the operator "+" normally acts as an arithmetic operator unless one of its operands is a String. If necessary it converts the other operand to a String before joining the second operand to the end of the first operand.

when a + is used for concatenation below are the steps which are involved:
  1. A StringBuffer object is created
  2. string1 is copied to the newly created StringBuffer object
  3. The “*” is appended to the StringBuffer (concatenation)
  4. The result is converted to back to a String object.
  5. The string1 reference is made to point at that new String.
  6. The old String that string1 previously referenced is then made null.
To join the two Strings "pan" and "handle":
 System.out.println("pan" + "handle"); 
If one of the operands is not a String it will be converted:
 int age = 12; 
System.out.println("My age is " + age);
There is also a method called concat defined in the String class that performs the same operation:

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