通过非静态方法更改公共静态变量

Question

I am implementing the same in a different context. I want to change the value of a static variable by calling non static Method as below,

public static staticVar = changetheStatic();
public String changetheStatic(){
return "valueChanged";`
}

I am getting error like the "Change the method to static".. so any suggestions..??

Answer 1

This simply can't work.

You can only invoke non static methods on some instance . In your example, there is no instance; thus the compiler would only allow you to call a static method.

And just for the record: the naming is confusing. You called your method changeTheStatic() . But that method doesn't change anything . It only returns a value. So you should be calling it something like getInitialValue() for example.

Answer 2

You can't do this. You are trying to call an instance method without initializing an object. Instead what you can do is do this in you constructor

          public class A {
           public static staticVar ;

           public A() {
                  A.staticVar = this.changetheStatic()
           }
           public String changetheStatic(){
             return "valueChanged";`
           }
         }

If you don't want to change it in the constructor, you can simply initialize an object and call the instance method

                System.out.println(A.staticVar);//old value
                new A().changetheStatic();//will call instant method related to the new instantiated object , note i did not give it a reference so GC will free it cuz i only need it to change the static variable

                System.out.println(A.staticVar);//new value

The whole idea here is what you are doing is trying to call instant method as static, instant method needs to be called from an object

         public static staticVar = changetheStatic();

so changing changetheStatic() to static would work too.

Answer 3

You can't simply call methods like this as static variables are created when the class is initialised. It means that these static variables will exist even if there's no instance of the class.

Hence you can only do this by changing the changetheStatic() method to static

public static staticVar = changetheStatic();
public static String changetheStatic(){
    return "valueChanged";`
}