Java Examples - Concatenate strings

Problem Description:

How to optimize string concatenation ?

Solution:

Following example shows performance of concatenation by using "+" operator and StringBuffer.append() method.

public class StringConcatenate{
   public static void main(String[] args){
      long startTime = System.currentTimeMillis();
      for(int i=0;i<5000;i++){
         String result = "This is"
         + "testing the"
         + "difference"+ "between"
         + "String"+ "and"+ "StringBuffer";
      }
      long endTime = System.currentTimeMillis();
      System.out.println("Time taken for string" 
      + "concatenation using + operator : " 
      + (endTime - startTime)+ " ms");
      long startTime1 = System.currentTimeMillis();
      for(int i=0;i<5000;i++){
         StringBuffer result = new StringBuffer();
         result.append("This is");
         result.append("testing the");
         result.append("difference");
         result.append("between");
         result.append("String");
         result.append("and");
         result.append("StringBuffer");
      }
      long endTime1 = System.currentTimeMillis();
      System.out.println("Time taken for String concatenation" 
      + "using StringBuffer : "
      + (endTime1 - startTime1)+ " ms");
   }
}

Result:

The above code sample will produce the following result.The result may vary.

Time taken for stringconcatenation using + operator : 0 ms
Time taken for String concatenationusing StringBuffer : 16 ms