将JTabbedPane添加到JTabbedPane错误中

Question

得到这个错误:

线程"AWT-EventQueue-0"异常Project.reportpane.addComponent (reportpane.java: 69)

我无法将rptinvestment选项卡窗格添加到面板tabinvestment

公共类reportpane扩展JPanel {

JTabbedPane rpt;
JPanel tabcashflow;
JPanel tabinvestment;
JPanel tabexchangerates;
JTabbedPane rptinvestment;
JPanel tabofficial;
JPanel tabdem;
JPanel tabcommodities;
public reportpane() {
    rpt = new JTabbedPane();
    tabcashflow = new JPanel();
    tabinvestment = new JPanel();
    tabexchangerates = new JPanel();
    tabofficial = new JPanel();
    tabdem = new JPanel();
    tabcommodities = new JPanel();

    rpt.add("Cashflow", tabcashflow);
    rpt.add("Investement", tabinvestment);
    rpt.add("Exchange rates", tabexchangerates);
    rpt.setBackground(new Color(255, 255, 255));
    rpt.setFont(new Font("sansserif", Font.PLAIN, 14));
    rpt.setTabPlacement(javax.swing.JTabbedPane.TOP);
    rpt.setBorder(BorderFactory.createEmptyBorder());
    rpt.setSize(750, 500);

    rptinvestment = new JTabbedPane();
    rptinvestment.add("Official", tabofficial);
    rptinvestment.add("DEM", tabdem);
    rptinvestment.add("Commodities", tabcommodities);
    rptinvestment.setBackground(new Color(255, 255, 255));
    rptinvestment.setFont(new Font("sansserif", Font.PLAIN, 14));
    rptinvestment.setTabPlacement(JTabbedPane.TOP);
    rptinvestment.setBorder(BorderFactory.createEmptyBorder());
    rptinvestment.setSize(750, 500);
    addComponent(tabinvestment, rptinvestment, 0, 0, 675, 570);
    addComponent(this, rpt, 10, 10, 675, 570);

    this.setLayout(new BorderLayout());
    this.setBackground(Color.WHITE);
    this.setBorder(null);
    this.revalidate();
    this.repaint();
}
public void addComponent(Container container, Component c, int x, int y, int width, int height) {
    c.setBounds(x, y, width, height);
    container.add(c);
}

}

Answer 1

您从未初始化tabinvestment。您将其声明为实例变量，但从不在构造函数中初始化它。有时需要调用JTabbedPane tabinvestment = new JTabbedPane()

Answer 2

您尝试使用被布局管理器覆盖的绝对定位添加组件

JTabbedPane使用自己的布局逻辑，除非你真的要创建自己的UI类，否则不能更改。

同样，您已经将框架布局管理器设置为BorderLayout，这将覆盖任何可能已设置的定位值(之前设置为其他)