不断收到错误“组件必须可显示”

Question

您好，我不断收到错误“组件必须可显示”并且无法解决它，我查看了有关 SO 的问题并尝试了解决方案，但无济于事。我正在尝试实现一个 JVLC 播放器，当我在 Vid 类中尝试“ .setVideoOutput(canvas1) ”时会发生错误，

这里是主类。

import java.awt.Component;
import java.awt.Toolkit;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
import java.util.logging.Level;
import java.util.logging.Logger;



/**
 *
 * @author Shane
 */
public class Main extends javax.swing.JFrame {

    private LessonPanel lesson;
    private MultiChoice multiChoice;
    private Vid video;
    private int xSize;
    private int ySize;

    public Main() throws InterruptedException {

        Toolkit tk = Toolkit.getDefaultToolkit();

        xSize = ((int) tk.getScreenSize().width/2);
        ySize = ((int) tk.getScreenSize().height/2);
        this.setSize(xSize, ySize);
        this.setVisible(true);

        System.out.print("\nIsDisplayable "+this.isDisplayable());
        addVideo();


        WindowListener listener = new WindowAdapter() {

            @Override
            public void windowClosing(WindowEvent w) {
                System.exit(0);
            }
        };
        this.addWindowListener(listener);
    }

    public void next(String method) throws InterruptedException{

        if(method.equalsIgnoreCase("home")){home();}
        else if(method.equalsIgnoreCase("Multi")){addMultiChoice();}
        else if(method.equalsIgnoreCase("Video")){addVideo();}
        else if(method.equalsIgnoreCase("Visual")){addVisual();}


    }

    public void removePanels(Component Comp,String doNext) throws InterruptedException {

        this.remove(Comp);
        this.repaint();

        next(doNext);

    }

    public void home() throws InterruptedException {

        lesson = new LessonPanel(this);
        this.add(lesson);
        this.validate();
        this.repaint();
    }

    public void addMultiChoice() throws InterruptedException {

        multiChoice = new MultiChoice(this);
        this.add(multiChoice);
        this.validate();
        this.repaint();


    }

    public void addVideo() throws InterruptedException {
        this.invalidate();
        video = new Vid();
        this.add(video);
        this.validate();
        this.repaint();


    }

    public void addVisual() throws InterruptedException {

    }

    public static void main(String args[]) {

        java.awt.EventQueue.invokeLater(new Runnable() {

            public void run() {
                try {

                    new Main().setVisible(true);

                } catch (InterruptedException ex) {
                    Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
                }



            }
        });



    }
}

这就是给我错误的课程

import java.awt.Canvas;
import java.awt.Color;
import org.videolan.jvlc.JVLC;


public class Vid extends javax.swing.JPanel
{

   private static String filename ="C:/Users/Public/Videos/Sample Videos/Wildlife.wmv";
   private Canvas canvas;


    public Vid()
    {
          init();
    }

    public void init(){


           System.out.print("\nReady to play video");
           canvas = new java.awt.Canvas();
           canvas.setBackground(Color.red);
           canvas.setSize(400, 400);
           canvas.setVisible(true);

           add(canvas);



           String[] arg = new String[4];
                    arg[0] = "--intf=dummy";
                    arg[1] = "--ignore-config";
                    arg[2] = "--no-plugins-cache";
                    arg[3] = "--plugin-path=plugins";




          JVLC jvlc = new JVLC(arg);
          jvlc.play(filename);
          jvlc.setVideoOutput(canvas);


       }

}

任何帮助都会很棒！提前致谢！！

Answer 1

我猜想当您尝试执行该方法时该面板不可见。您将组件添加到面板，但面板尚未添加到框架。重构您的代码，例如：

video = new Vid();
this.add(video);
this.revalidate(); // 
this.repaint(); 
video.someMethodToInvoke "setVideoOutput"