String and String Buffer Comparison

Thinking java String concatenation internally uses StringBuffer to do the concatenation operation, we do concatenation as mentioned below in java code,

String str=a+b; a and b is string objects.

java compiler compiles above code in this fashion:

String str=(new StringBuffer()).append(a).append(b).toString());

    Above code creates two objects, and as you must be knowing that java maintains the string data in char array which is also an object so it creates 1 more object. So in total 3 objects gets created for one concatenation operation. Please note that object creation is one of the costliest operation in java.

    I created one test program just to see the performance difference and results were dramatic... i ran both loop in same program 1 million times. See the time difference... So based on below result its  recommended to use StringBuffer.append whenever you are doing any concatenation operation in java...

    time taken by string: 78080 (ms)
    time taken by String buffer: 31 (ms)