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java – 在单击按钮时打开时,新JFrame处于禁用状态

发布时间:2020-12-15 02:15:50 所属栏目:Java 来源:网络整理
导读:我陷入了一种非常不寻常的境地.我有一个类“ScreenSizeSelector”,它有一个方法’getSelectedScreenSize’.该方法的工作是创建UI,用户拖动UI和方法返回窗口大小. 现在我通过以下方式调用类的方法: 一个简单的类(非GUI) 在按钮上单击JFrame 在第一种情况下,
我陷入了一种非常不寻常的境地.我有一个类“ScreenSizeSelector”,它有一个方法’getSelectedScreenSize’.该方法的工作是创建UI,用户拖动UI和方法返回窗口大小.

现在我通过以下方式调用类的方法:

>一个简单的类(非GUI)
>在按钮上单击JFrame

在第一种情况下,它工作得很好(即大小选择器窗口打开,用户拖动它,调整大小并返回窗口坐标)但在第二种情况下,窗口打开但在禁用模式下,用户无法执行任何操作在窗户上操作,甚至无法关闭窗户.

这是我正在使用的代码

ScreenSizeSelector类:

package screenrecorder;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Rectangle;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;

import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.Border;


class ScreenSizeSelector {

    private JFrame sizeSelectorWindow;
    private JButton btnOk;
    private Border emptyBorder;
    private Rectangle screenArea = null;
    private static Object lock = new Object();



    public Rectangle getSelectedScreenSize(){

        screenSizeSelectorUI();

        Thread t = new Thread() {
            public void run() {
                synchronized(lock) {
                    while (sizeSelectorWindow.isVisible())
                        try {
                            lock.wait();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                }
            }
        };

        t.start();
        try {
            t.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        return screenArea;
    }


    public void screenSizeSelectorUI() {
        emptyBorder = BorderFactory.createEmptyBorder();

        sizeSelectorWindow = new JFrame("Select screen area");

        btnOk = new JButton("Start");
        sizeSelectorWindow.setUndecorated(true);
        sizeSelectorWindow.getRootPane().setWindowDecorationStyle(3);
        sizeSelectorWindow.setBackground( new Color(0,0) );
        sizeSelectorWindow.setSize(400,400);

        sizeSelectorWindow.addWindowListener(new WindowEventHandler());
        sizeSelectorWindow.setAlwaysOnTop(true);
        sizeSelectorWindow.setLocationRelativeTo(null);


        btnOk.setToolTipText("Click this button after deciding the screen area");
        btnOk.addActionListener(new ButtonEventHandler());


        JPanel buttonPanel = new JPanel(new FlowLayout(FlowLayout.RIGHT));
        buttonPanel.setBackground(new Color(0,0));
        buttonPanel.add(btnOk);
        sizeSelectorWindow.add(buttonPanel,BorderLayout.SOUTH);

        sizeSelectorWindow.setVisible(true);
        sizeSelectorWindow.setEnabled(true);

    }

class ButtonEventHandler implements ActionListener {

@Override
public void actionPerformed(ActionEvent e) {

    int x = (int)(sizeSelectorWindow.getBounds().getX());
    int y = (int) (sizeSelectorWindow.getBounds().getY());
    int width = sizeSelectorWindow.getWidth();
    int height = sizeSelectorWindow.getHeight();

    screenArea = new Rectangle(x,y,width,height);
    sizeSelectorWindow.dispatchEvent(new WindowEvent(sizeSelectorWindow,WindowEvent.WINDOW_CLOSING));
}


}

class WindowEventHandler implements WindowListener{

    @Override
    public void windowOpened(WindowEvent e) {
    }

    @Override
    public void windowClosing(WindowEvent e) {

        synchronized (lock) {
            sizeSelectorWindow.setVisible(false);
            lock.notify();
        }
    }

    @Override
    public void windowClosed(WindowEvent e) {
    }

    @Override
    public void windowIconified(WindowEvent e) {
        sizeSelectorWindow.setState(JFrame.NORMAL);
        Toolkit.getDefaultToolkit().beep();
    }

    @Override
    public void windowDeiconified(WindowEvent e) {}

    @Override
    public void windowActivated(WindowEvent e) {}

    @Override
    public void windowDeactivated(WindowEvent e) {}


    }

}

Test1类:

package screenrecorder;

import java.awt.Rectangle;

public class Test1{

    public static void main(String[] args){
        System.out.println(new ScreenSizeSelector().getSelectedScreenSize());
    }
}

Test2类:

package screenrecorder;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;

public class Test2 extends JFrame{

    public Test2(){

        JButton btn = new JButton("Click ME");
        btn.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                System.out.println(new ScreenSizeSelector().getSelectedScreenSize());

            }
        });

        getContentPane().add(btn);
        setSize(100,100);
        setVisible(true);
        setDefaultCloSEOperation(JFrame.EXIT_ON_CLOSE);

    }

    public static void main(String[] args){
        new Test2();
    }

}

任何帮助表示赞赏.

解决方法

单击该按钮时,动作侦听器将等待getSelectedScreenSize()函数返回.并且getSelectedScreenSize()函数正在等待screenSelectorUI()创建的第二个窗口不可见. screenSelectorUI()确实创建了第二个窗口,但是你设置了这样的颜色:

sizeSelectorWindow.setBackground( new Color(0,0) );

如果你看一下颜色构造函数javadocs:

06001

Creates an sRGB color with the specified red,green,blue,and alpha values in the range (0 – 255).
Parameters:

  • r – the red component
  • g – the green component
  • b – the blue component
  • a – the alpha component

您将alpha值设置为0,使其完全不可见. (alpha值是透明度),第二个窗口是未修饰的,不会在关闭时退出,所以你根本不知道它在那里.

我得不到的是test1是如何工作的.
旁注:当我在Mac上尝试测试1时,它只显示按钮,我所能做的就是点击它.按钮将消失,但应用程序仍将运行.

这基本上是一个猜测,但很多swing组件向操作系统发出请求,而不是命令.有点像说,“嘿,我可以把它调到400,400吗?”操作系统在技术上不必做你说的.我正在阅读How does Java handle multithreading?,它说多线程真的取决于操作系统.我有一种感觉,当它自己调用screenSelectorUI()时会在某处弄乱,但是当它在某个按钮的线程内时,它会以某种方式正确.

(编辑:李大同)

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