内部面板的 Java getheight() 和 getWidth() 未设置为固定大小

Question

我想获取内面板的高度和宽度。 我使用 Miglayout 将高度和宽度设置为 100%。 当我运行我的代码时，我的高度和宽度都为零。

class MiglayoutExample extends JFrame {

static JFrame frame;
public static void main(String[] args) {
    frame = new JFrame("frame");

    JPanel bluePanel = new JPanel();
    bluePanel.setLayout(new MigLayout());
    bluePanel.setBackground(Color.BLUE);

    JPanel redPanel = new JPanel();
    redPanel.setBackground(Color.RED);

    bluePanel.add(redPanel, "width 100%, height 100%");

    frame.add(bluePanel);

    frame.setSize(600, 600);
    System.out.println("bluePanel.getHeight() = " + bluePanel.getHeight()); //Output 0
    System.out.println("bluePanel.getWidth() = " + bluePanel.getWidth());       //Output 0
    System.out.println("redPanel.getHeight() = " + redPanel.getHeight());       //Output 0
    System.out.println("redPanel.getWidth() = " + redPanel.getWidth());         //Output 0

    frame.show();
}
}

Answer 1

您的面板没有尺寸。 您应该设置面板的大小

redPanel.setSize(600, 600);
bluePanel.setSize(600, 600);

或获取帧大小

    System.out.println("frame.getHeight() = " + frame.getHeight()); 
    System.out.println("frame.getWidth() = " + frame.getWidth());