向JFrame添加图像

Question

I want to add an Image to the JFrame, the add( ) method is generating an error which says "cannot find symbol: method add(JLabel)" ... How can I fix that?

** I still haven't called the ImageLoading( ) method from the main method.

import javax.swing.*;

public class NetworkingGame {

NetworkingGame(){
    JFrame jfrm = new JFrame("Angry Painters");
    jfrm.setSize(800, 480);
    jfrm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    jfrm.setVisible(true);

}

public void ImageLoading(){
    ImageIcon i = new ImageIcon("angry-painters.jpg");
    JLabel jl = new JLabel(i);
    add(jl); //The error is in this line
}

public static void main(String[] args) throws Exception{
    SwingUtilities.invokeLater(new Runnable(){

        @Override
        public void run(){
            new NetworkingGame();
        }
    });

   }
}

Answer 1

Visibility of JFrame jfrm is limited by constructor of NetworkingGame . So add method does not exist in NetworkingGame . Make your JFrame member of NetworkingGame .

public class NetworkingGame {
    private JFrame jfrm;

    NetworkingGame(){
        jfrm = new JFrame("Angry Painters");


    ...

        JLabel jl = new JLabel(i);
        jfrm.add(jl);

Answer 2

Probably you should write

jfrm.add(jl); 

and have jfrm as a member.

In you case you really calling this.add() which is not exist.

Answer 3

You are calling the add method as if it was an instance method in your class NetworkingGame and your class doesn't have any method, so you are getting the compiler error as the compiler can't find any method of such a name in your class NetworkingGame , so add it to the Jframe instead.

NetworkingGame(){
    JFrame jfrm = new JFrame("Angry Painters");
    jfrm.setSize(800, 480);
    jfrm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    jfrm.setVisible(true);
    ImageIcon i = new ImageIcon("angry-painters.jpg");
    JLabel jl = new JLabel(i);
    jfrm.add(jl);
}