/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
String s1 = "abc";
String s2 = "pqr";
System.out.println((s1 + s2) == (s1 + s2));  // false
 
final String s3 = "abc";
final String s4 = "pqr";
 
// true, because s3+s4 is a constant, and thus the compiler puts the 
// value in the constant pool.
System.out.println((s3 + s4) == (s3 + s4));
 
// false, because the value of concat isn't a compile-time constant.
System.out.println(s3.concat(s4) == s3.concat(s4));
	}
}

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