Using String variable for "for loop" in Java

Question

public class ForTest{
    public static void main(String[] args)
    {
         String s;
         for(s="ha"; s!="haha"; s=s+"ha"){
            System.out.println(s);
          }
     }
}

In my opinion, this code should work which just print "ha", Because after one loop, s="ha" would become s="haha" and then it will stop the loop. However, it doesn't stop and shows infinite looping.

Could you help me to know what is the reason of it?

You are using string and String is immutable and you are comparing object.It will always return false. — praveen_programmer, Dec 29 '14 at 09:30

score 1 · Answer 1 · answered Dec 29 '14 at 09:29

1

I would rather use it like this:

public class ForTest{
    public static void main(String[] args)
    {
         String s;
         for(s="ha"; !s.equals("haha"); s=s+"ha"){
            System.out.println(s);
          }
     }
}

answered Dec 29 '14 at 09:29

Darshan Lila

5,772
2
24
34

score 0 · Accepted Answer · answered Dec 29 '14 at 09:31

Well, simply put ha + ha will not be == to haha. Use it like this :

    for (s = "ha"; (!s.equals("haha")); s = s + "ha") {
        System.out.println(s);
    }

== compares if 2 references point to the same object. equals() checks if 2 references point to objects with same values.

score 0 · Answer 3 · answered Dec 29 '14 at 09:31

0

If you have need you can do like this.

public class ForTest{
    public static void main(String[] args)
    {
         String s;
         for(s="ha"; !s.equals("haha"); s=s+"ha"){
            System.out.println(s);
          }
     }
}

answered Dec 29 '14 at 09:31

praveen_programmer

1,072
11
25

Using String variable for "for loop" in Java

3 Answers3