Question

public class Main {

    public static void main(String[] args){

        Class2 class2Object = new Class2();

        //class2Object
        //num1
        class2Object.setNumber(class2Object.number1, 1) ;

        class2Object.getNumber(class2Object.number1);
    }   

}

public class Class2 {
    public int number1;

    public void setNumber(int x, int value){
        x = value;

    }
    public void getNumber(int number){
        System.out.println("Class2, x = "+number);
    }
}

I have 2 class: Class2 and Main. I assign an instance variable to 1 in Main class. Why is class2Object.number1 not assign to a value of 1? Output is 0.

Answer 1

Your setter doesn’t do anything:

public void setNumber(int x, int value){
    x = value;   // This just overwrites the value of x!
}

A setter should have only one parameter. You need to assign the received value to the member field:

// The field should be private.
private int number;

public void setNumber(int value){
    this.number = value;
}