From static main method in same outer class like inner class, can't access to constructor from inner class

Question

Why this happened, it gives me error in void main when initializing newString, this The method StringThread(String, int) is undefined for the type mainThread ? Here is code:

public class mainThread {

    public class StringThread implements Runnable {

        private int num;
        private String text;

        public StringThread(String text, int num){
            this.text = text;
            this.num = num;
        }

        public void run(){
            for(int i = 0; i < num;i++)
                System.out.println(i+1+". " + text);
        }

    }

    public static void main(String[] args){
        StringThread newString;
        newString  = StringThread("Java", 30);
        new Thread(newString).start();
    }

}

12dollar · Answer 1 · 2015-07-14T14:01:12.460

1

 StringThread newString = new mainThread().new StringThread("Java", 30);

You didn't initialize it oO

edited Jul 14 '15 at 14:01

answered Jul 14 '15 at 13:55

12dollar

645
3
17

Actually, it needs to be: new mainThread().new StringThread("Java", 30); – Stultuske Jul 14 '15 at 13:58
happens if fingers move faster than your brain can handle ;) thanks – 12dollar Jul 14 '15 at 14:01

score 0 · Accepted Answer · edited May 23 '17 at 11:52

0

new keyword is missing in your initialization and that's why it is considering it as a method and not constructor and as it's inner class it should be. (Suggested by Stultuske)

mainThread obj = new mainThread();
StringThread newString = new obj.StringThread("Java", 30);//new keyword is missing

Please read following answer to understand why we need to do this to access inner class,

Java inner class and static nested class

edited May 23 '17 at 11:52

Community

1
1

answered Jul 14 '15 at 13:56

akash

22,664
11
59
87

Actually, it needs to be: new mainThread().new StringThread("Java", 30); – Stultuske Jul 14 '15 at 13:58
Thanks, so silly stupid mistake, but now it say:No enclosing instance of type mainThread is accessible. Must qualify the allocation with an enclosing instance of type mainThread (e.g. x.new A() where x is an instance of mainThread). – Stefan Eftan Jul 14 '15 at 13:59
Stefan: that is why I added my comment. You need to go through an instance of mainThread, since your StringThread class is located within mainThread, and the static main method belongs to mainThread. – Stultuske Jul 14 '15 at 14:00

From static main method in same outer class like inner class, can't access to constructor from inner class

2 Answers2