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

genek Published at Dev

genek

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;
    }
}
}

}

Nir Alfasi

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;
        }
    }
}

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