java: non-static variable this cannot be referenced from a static context

Question

I have error java:

non-static variable this cannot be referenced from a static context

when compiling the code in line

Man m1 = new Man("a1", "b1", 11);

How to fix that?

public class Solution
{
   public static void main(String[] args)
   {
      //create two object of every class here
      Man m1 = new Man("a1", "b1", 11);
      Man m2 = new Man("a2", "b2", 12);
      Woman w1 = new Woman("a11", "b11", 13);
      Woman w2 = new Woman("a22", "b22", 14);

       //output them to screen here
       System.out.println(m1.name + " " + m1.age + " " + m1.address);
        System.out.println(m2.name + " " + m2.age + " " + m2.address);
        System.out.println(w1.name + " " + w1.age + " " + w1.address);
        System.out.println(w2.name + " " + w2.age + " " + w2.address);
}

    //add your classes here
    public class Man
    {
        private String name;
        private String address;
        private int age;

        public Man(String name, String address, int age)
        {
            this.name = name;
            this.address = address;
            this.age = age;
        }
    }
    }
}

or more simply (mycompiler.io fiddle)

class HelloWorld {

    public static void main(String[] args) {
        new Tester("hello");
    }
    
    class Tester {
        public Tester(String s) { }
    }
}

Do you want help to understand what the error means, or simply help to fix the problem? A static context means you are not in an "instance" of a class (and hence it does not have any member data/functions etc) - therefore when you access a non-static variable (which would only exist for an instance of the class) it says you can't, as you have no instance. — Chris Cousins, Jul 28 '17 at 18:58
Your Man class is not static. This means it must have a reference to the outerclass.main is static and has no implicit outerclass. The simple solution is make your Man class static. — Mayur Patel, Jul 28 '17 at 19:17
Not a duplicate, as the other answer doesn't address the `this`. — Ian Boyd, Jul 25 '22 at 20:03
@IanBoyd I replaced the duplicate with one that does match the question. — Mark Rotteveel, Jul 28 '22 at 09:16

Nir Alfasi · Accepted Answer · 2017-07-28T19:14:45.743

One approach

Declare Man class as static and you'll be able to access it from within main() which is static as well (not tied to any instance of class Solution):

public static class Man

Another approach

We can also leave class Man non-static and create an instance-level factory-method which will create instances of Man:

public class Solution {

    public static void main(String[] args) {
        //create two object of every class here
        Solution solution = new Solution();
        Man m1 = solution.createMan("a1", "b1", 11);
        Man m2 = solution.createMan( "a2", "b2", 12);

        //output them to screen here
        System.out.println(m1.name + " " + m1.age + " " + m1.address);
        System.out.println(m2.name + " " + m2.age + " " + m2.address);    
    }

    Man createMan(String name, String address, int age) {
        return new Man(name, address, age);
    }

    //add your classes here
    public class Man {
        private String name;
        private String address;
        private int age;

        private Man(String name, String address, int age) {
            this.name = name;
            this.address = address;
            this.age = age;
        }
    }
}

score -2 · Answer 2 · edited Mar 03 '19 at 00:17

-2

public class Main {

    public static void main(String[] args) {
        // write your code here
        VerySimple alice = new VerySimple();
    }

    class VerySimple {
        private int age;
        private String name;
        //constructor

        VerySimple(int age, String name) {
            this.age = age;
            this.name = name;
        }

        //getter method
        int getAge() {
            return age;
        }

        //setter method
        public void setAge(int a) {
            age = a;
        }

        //getter
        String getName() {
            return name;
        }
    }
}

edited Mar 03 '19 at 00:17

zmag

7,825
12
32
42

answered Mar 02 '19 at 15:26

gukahhh

1
2

Don't waste your time answering old beginners questions that *should have been* closed as dups years ago. Also, code-only answer are not much help. You should start by explaining the point your code is designed to illustrate. The explanation should be the real answer; the code is just the illustration. – Stephen C Mar 03 '19 at 00:24

java: non-static variable this cannot be referenced from a static context

2 Answers2

One approach

Another approach