Program to demonstrate working of intern() method in String class through a example.
Output of the program :
package com.hubberspot.examples;
public class InternDemo {
public static void main(String[] args) {
// Using new String() each time the line
// executes a new instance is created
// Avoid this kind of usage of String
// creation
String name1 = new String("Hubberspot");
// String instance should be created by
// below statement. It maintains and avoids
// new creation of instance each time
// the line gets executed.
String name2 = "Hubberspot";
// Before calling intern() method lets test reference value
// equality of both name1 and name2 String objects.
if(name1 == name2){
System.out.println("Before calling intern() : name1 == name2 is true");
}
else {
System.out.println("Before calling intern() : name1 == name2 is false");
}
// Whenever an String object is created by using new operator
// always a new object gets created in the heap whether
// it has same value or not.
// Whenever an String object is created by using "" a constant
// string object gets created in the heap memory.
// The difference is shown by above example i.e before calling
// intern() method.
// When the intern method is invoked, if the pool already
// contains a string equal to this String object as determined
// by the equals(Object) method, then the string from the pool
// is returned. Otherwise, this String object is added to the
// pool and a reference to this String object is returned.
name1 = name1.intern();
// After intern method gets executed name1 is added to the
// String constant pool and reference is returned back to
// name1.
// Below results shows the variation in the result ...
if(name1 == name2){
System.out.println("After calling intern() : name1 == name2 is true");
}
else {
System.out.println("After calling intern() : name1 == name2 is false");
}
}
}
Output of the program :