Question

为什么jPanel在启动时返回高度和宽度为0，如何在启动时获得正确的值。

import javax.swing.JPanel;

class ZeroJPanel extends JPanel {

    /**
     * Creates new form ZeroJPanel
     */
    ZeroJPanel() {
        initComponents();

        System.out.println( this.getHeight() );
    }


    public static void main(String Args[]) {
        new ZeroJPanel();
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        org.jdesktop.layout.GroupLayout layout = new org.jdesktop.layout.GroupLayout(this);
        this.setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(0, 400, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(0, 300, Short.MAX_VALUE)
        );
    }// </editor-fold>
    // Variables declaration - do not modify
    // End of variables declaration
}

Answer 1

面板返回0, 0，因为很简单，这是默认值。

将面板添加到框架并在框架上调用pack()时，将计算正确（首选）尺寸并进行设置。在此之前，您将无法找到尺寸，因为它尚未计算。

为什么需要这些值？如果您能从更广泛的角度解释问题，我们可以帮助您。

零宽度高度jPanel启动时

1 个答案: