java Board的方块不会出现。

Question

我有三门课：一门是主课：

public class Thera {
    public static void main(String[] args) {
        TheraGUI start = new TheraGUI();
    }

}

一个是GUI

public class TheraGUI extends JFrame {
    public TheraGUI(){
        Board board = new Board();
        this.setLayout(new GridBagLayout());
        this.setTitle("Thera");
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setVisible(true);
        this.add(board);
        this.pack();
    }
}

最后是我的董事会：

package thera;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;

public class Board extends JPanel {
  JLayeredPane layeredpane;
  JPanel board;
  JLabel piece;
  int xAdj;
  int yAdj;
  private static final String imageFolderPath = "src/resources/images/";
  Dimension dimension = new Dimension(500, 500);

  public Board(){
      //create the layered pane  
      layeredpane = new JLayeredPane();
      layeredpane.setPreferredSize(dimension);
      this.add(layeredpane);

  //create the Board
  board = new JPanel();
  board.setLayout(new GridLayout(7,9));
  board.setPreferredSize(dimension);

  layeredpane.add(board, JLayeredPane.DEFAULT_LAYER);

  for(int c = 0; c < 7; c++){
      for(int r = 0; r < 9; r++){
          JPanel square = new JPanel(); 
          square.setLayout(new BorderLayout());
          square.setBackground(new Color(255, 204, 051));
          board.add(square);
      }
  }

 } 

}

我的问题是：我的董事会不会出现！ 附加信息：主布局是gridbaglayout，在第一单元中我添加了一个JPanel，在JPanel中我添加了一个layeredpane

Answer 1

在设置可见性之后，您将添加一个组件（从而更改层次结构）。Swing在工作方式上有点迂腐

public class TheraGUI extends JFrame {
    public TheraGUI(){
        Board board = new Board();
        this.setLayout(new GridBagLayout());
        this.setTitle("Thera");
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        // note the order
        this.add(board);
        this.pack();
        this.setVisible(true);
    }
}