JAVA EE: Java Tutorial : Java String vs StringBuffer (Hashcode difference)

Tuesday 26 April 2016

Java Tutorial : Java String vs StringBuffer (Hashcode difference)

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HashCodeTest.java

public class HashCodeTest
{

    public static void main(String[] args)
    {

        System.out.println("Hashcode test of String:");
        
        /*
         * String is immutable(once created, can not be
         * modified).
         */
        String str = "Welcome";
        
        System.out.println("Before Concat,HashCode = "
                + str.hashCode());
        
        str = str + "Peter";
        
        System.out.println("After Concat,HashCode  = "
                + str.hashCode());

        System.out.println("---------------------------------");

        System.out.println("Hashcode test of StringBuffer:");

        /*
         * StringBuffer is mutable (once created, can be
         * modified.
         */
        StringBuffer sb = new StringBuffer("Welcome");
        
        System.out.println("Before Concat,HashCode = "
                + sb.hashCode());
        
        sb.append("Peter");
        
        System.out.println("After Concat,HashCode  = "
                + sb.hashCode());

    }
}

Output

Hashcode test of String:
Before Concat,HashCode = -1397214398
After Concat,HashCode  = 44468202
---------------------------------
Hashcode test of StringBuffer:
Before Concat,HashCode = 1704856573
After Concat,HashCode  = 1704856573