StringBuffer and StringBuilder

StringBufferAndBuilder.java

package com.diycomputerscience;

public class StringBufferAndBuilder { 
	
  public static final int MAX_ITER = 10000;

  /**
   * @param args
   * This example shows how to perform common String operations in Java 
   */
  public static void main(String[] args) {
		
  //We will concatenate Strings in three different ways, in the 
  //methods below
		
  long t1 = concatenateWithPlusOperator();
  long t2 = concatenateWithStringBuffer();
  long t3 = concatenateWithStringBuilder();
		
  //All of the above ways of concatenating have performance
  //implications. Let us see the difference in performance.
		
  //Using StringBuffer is faster than using the '+' operator
  System.out.println("ConcatenateWithStringBuffer is " + 
                     (double)t1/(double)t2 + 
                     " times faster than Concatanate");

  //Using StringBuilder is faster than using StringBuffer
  System.out.println("ConcatanateWithStringBuilder is " + 
                     (double)t2/(double)t3 + 
                     " times faster than ConcatanateWithStringBuffer");
	
  }

  private static long concatenateWithPlusOperator() {
    String s1 = "";
    long s1Time = getNanoTime();
    for(int i=0;i<MAX_ITER;i++) {
      s1 = s1 + "abc";
    }
    long e1Time = getNanoTime();
    System.out.println("Time taken to concatenate using '+' : " + 
                       (e1Time - s1Time) + " nanoseconds");
    return e1Time - s1Time;
  }
	  
  private static long concatenateWithStringBuffer() {
    StringBuffer sb = new StringBuffer();
    long s2Time = getNanoTime();
    for(int i=0;i<MAX_ITER;i++) {
      sb.append("abc");
    }
    long e2Time = getNanoTime();
    System.out.println("Time taken to concatenate using StringBuffer: " + 
		       (e2Time - s2Time) + " nanoseconds");
    return e2Time - s2Time;		
  }
	
  private static long concatenateWithStringBuilder() {
    StringBuilder sBuilder = new StringBuilder();
    long s3Time = getNanoTime();
    for(int i=0;i<MAX_ITER;i++) {
      sBuilder.append("abc");
    }
    long e3Time = getNanoTime();
    System.out.println("Time taken to concatenate using StringBuilder: : " + 
                       (e3Time - s3Time) + " nanoseconds");
    return e3Time - s3Time;
  }
	
  private static long getNanoTime() {
    return System.nanoTime();
  }
}