Question

I have written a simple program that demonstrates garbage collection. Here is the code :

public class GCDemo{

public static void main(String[] args){
    MyClass ob = new MyClass(0);
    for(int i = 1; i <= 1000000; i++)
        ob.generate(i);
}

/**
 * A class to demonstrate garbage collection and the finalize method.
 */
class MyClass{
    int x;

    public MyClass(int i){
        this.x = i;
    }

    /**
     * Called when object is recycled.
     */
    @Override protected void finalize(){
        System.out.println("Finalizing...");
    }

    /**
     * Generates an object that is immediately abandoned.
     * 
     * @param int i - An integer.
     */
    public void generate(int i){
        MyClass o = new MyClass(i);
    }
}

}

However, when I try to compile it, it shows the following error :

Exception in thread "main" java.lang.Error: Unresolved compilation problem: 
    No enclosing instance of type GCDemo is accessible. Must qualify the allocation with an enclosing instance of type GCDemo (e.g. x.new A() where x is an instance of GCDemo).

    at GCDemo.main(GCDemo.java:3)

Any help? Thanks!

Answer 1

Make MyClass static:

static class MyClass {

Without this, you’ll have to have an instance of GCDemo in order to instantiate MyClass. You don’t have such an instance since main() itself is static.