Question

在我的代码中，我使用100多个预定义的JWindows在屏幕上与它们一起玩：显示或隐藏，移动等。定义如下：

    public static JWindow R2 = new JWindow();
    public static JWindow R3 = new JWindow();
    public static JWindow S2 = new JWindow();
    public static JWindow S3 = new JWindow();

    R2.getContentPane().add(s0.labelNow("/testingPackage/" + "R2" + ".jpg"));
    R2.pack();
    R2.setLocation(10, 350);
    R2.setVisible(true);
    R3.getContentPane().add(s0.labelNow("/testingPackage/" + "R3" + ".jpg"));
    R3.pack();
    R3.setLocation(40, 350);
    R3.setVisible(true);
    S2.getContentPane().add(s0.labelNow("/testingPackage/" + "S2" + ".jpg"));
    S2.pack();
    S2.setLocation(550, 750);
    S2.setVisible(true);   etc.

如您所见，这会导致真正的代码混乱，所以我想知道是否可以将JWindows放在数组或类似的东西中，以便可以使用类似'JWArray [4] [50]'和使用循环来声明，定义，移动，显示，隐藏它们？

请在下面的代码中尝试使用JWindows数组，这会在“ JWA [i] .getContentPane（）。add”行上导致空指针异常。我假设此JWA []声明一定是错误的。

import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JWindow;

public class ShowPicture3 extends JPanel {

public static JWindow[] JWA = new JWindow[5];
public static ShowPicture3 s0 = new ShowPicture3();

public JLabel labelNow(String path) {
    ImageIcon imgIcon = new ImageIcon(ShowPicture3.class.getResource(path));
    JLabel label = new JLabel(imgIcon);
    add(label);
    return label;
}

public void prepareImages() {
    for (int i = 0; i < 5; i++) {
        System.out.println("/testingPackage/" + "R" + (i + 2) + ".jpg");
        s0.labelNow("/testingPackage/" + "R" + (i + 2) + ".jpg");
        JWA[i].getContentPane().add(s0.labelNow("/testingPackage/" + "R" + (i + 2) + ".jpg"));
        JWA[i].pack();
        JWA[i].setLocation(10 + i * 20, 350);
        JWA[i].setVisible(true);
    }
}

public static void main(String[] args) throws Exception {
    s0.prepareImages();
    JWA[0].setLocation(100, 750);
    JWA[2].setVisible(false);
}

}

Answer 1

您忘了初始化JWA数组的内容（默认情况下以空值填充），只需添加“ JWA [i] = new JWindow（）;”即可。就像下面的示例一样。

public void prepareImages() {
    for (int i = 0; i < 5; i++) {
        JWA[i] = new JWindow();
        System.out.println("/testingPackage/" + "R" + (i + 2) + ".jpg");
        s0.labelNow("/testingPackage/" + "R" + (i + 2) + ".jpg");
        JWA[i].getContentPane().add(s0.labelNow("/testingPackage/" + "R" + (i + 2) + ".jpg"));
        JWA[i].pack();
        JWA[i].setLocation(10 + i * 20, 350);
        JWA[i].setVisible(true);
    }
}

如何在数组中使用JFrames或JWindows

1 个答案: