Java: Creating a new instance of the UI class

I have two classes: class A and class B. class A has a main method. Class B is the User Interface (JFrame). I want to have an instance of B in A, but when I write any of the following the program runs but no window shows:

public class A{
    static B d= new B();
        public static void main(String args[]){
                           d.setVisible(true);} }



public class A{
        public static void main(String args[]){
   开发者_开发百科      java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new B().setVisible(true);
            }
        });
        }}


public class A{
            public static void main(String args[]){
             B d= new B()
             d.setVisible(true); 
            }}

How can I show the window?

Unfortunately, you didn't show us the code for class B. Perhaps the following example can give you a hint:

public class B extends JFrame {
    public B() {
        super("Hello, JFrame!");
    }
}

public class A {
    public static void main(String[] args) {
        B b = new B();
        b.setSize(300, 400);
        b.setVisible(true);
    }
}

It's a very minimal example, but as you can see B inherits from JFrame. In A's main method, you first create a new instance of B, then set its size and make it visible.

It turns out that the problem was in class A. I had an instruction that was waiting for input from a stream before the new B() but it wasn't getting the input.