Swing顯示一些JLabels但不是其他人

Question

我正在爲簡單的battlships克隆設計一個簡單的GUI。我以前使用塗色方塊做過類似的事情，但決定用JPanel來嘗試。除了頂部的標籤（1-14）外，這裏的一切都按我的意圖工作。它顯示1到4之間的任何地方，但從來沒有全部14，並且它似乎有點隨機有多少出現。此代碼應該運行，以便問題很容易看到。打印語句只是爲了確認這些值是否正確。謝謝您的幫助！

import java.awt.Color; 
import java.awt.Container; 
import java.awt.Dimension; 
import java.awt.Rectangle; 

import javax.swing.JFrame; 
import javax.swing.JLabel; 
import javax.swing.JPanel; 

public class Foo { 
    private JFrame frame; 
    private JPanel[][] opponentBoard; 
    private JLabel[] coordLabels; 
    private final int FRAME_HEIGHT = 800; 
    private final int FRAME_WIDTH = 600; 
    private final int SQ_SIZE = 30; 
    public Foo() { 
     frame = new JFrame(); 
     frame.setBounds(new Rectangle(FRAME_WIDTH, FRAME_HEIGHT)); 
     frame.setVisible(true); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     frame.setBackground(Color.RED); // for debugging porpoises 
     frame.setLayout(null); 

     Container container = frame.getContentPane(); 
     container.setBackground(Color.BLACK); 
     container.setVisible(true); 

     opponentBoard = new JPanel[15][11]; 

     coordLabels = new JLabel[24]; 

     for (int i = 0; i < 15; i++) { 
      for (int j = 0; j < 11; j++) { 
       opponentBoard[i][j] = new JPanel(); 
       container.add(opponentBoard[i][j]); 
       opponentBoard[i][j].setLocation(i + i * SQ_SIZE, j + j * SQ_SIZE); 
       opponentBoard[i][j].setSize(new Dimension(SQ_SIZE, SQ_SIZE)); 
       opponentBoard[i][j].setVisible(true); 
       if ((i == 0)^(j == 0)) { 
        opponentBoard[i][j].setBackground(Color.GRAY); 
        if (i == 0) { 
         coordLabels[j - 1] = new JLabel((char) (j + 64) + ""); 
         opponentBoard[i][j].add(coordLabels[j - 1]); 
         System.out.println(j-1); 
        } 
        if (j == 0) { 
         coordLabels[i + 9] = new JLabel(i + ""); 
         System.out.println(i + 9 + " " + i + " " + coordLabels[i + 9].getText()); 
         opponentBoard[i][j].add(coordLabels[i + 9]); 
        } 
        opponentBoard[i][j].repaint(); 
       } else { 
        opponentBoard[i][j].setBackground(Color.DARK_GRAY); 
       } 
      } 
     } 
     opponentBoard[0][0].setBackground(Color.BLACK); 
    } 

    public static void main(String[] args){ 
     new Foo(); 
    } 
} 

Answer 1

所有面板都添加到容器後，需要調用container.validate()。此外，我將刪除內部for循環內的呼叫repaint()。

或者，您不能將框架設置爲可見，直到面板添加完成;這表現更好。

你的代碼的工作版本可以在這裏找到：

import java.awt.Color; 
import java.awt.Container; 
import java.awt.Dimension; 
import java.awt.Rectangle; 

import javax.swing.JFrame; 
import javax.swing.JLabel; 
import javax.swing.JPanel; 

public class Foo { 
    private JFrame frame; 
    private JPanel[][] opponentBoard; 
    private JLabel[] coordLabels; 
    private final int FRAME_HEIGHT = 800; 
    private final int FRAME_WIDTH = 600; 
    private final int SQ_SIZE = 30; 
    public Foo() { 
     frame = new JFrame(); 
     frame.setBounds(new Rectangle(FRAME_WIDTH, FRAME_HEIGHT)); 
     //frame.setVisible(true); Build the UI before making it visible 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     frame.setBackground(Color.RED); // for debugging porpoises 
     frame.setLayout(null); 

     Container container = frame.getContentPane(); 
     container.setBackground(Color.BLACK); 
     container.setVisible(true); 

     opponentBoard = new JPanel[15][11]; 

     coordLabels = new JLabel[24]; 

     for (int i = 0; i < 15; i++) { 
      for (int j = 0; j < 11; j++) { 
       opponentBoard[i][j] = new JPanel(); 
       container.add(opponentBoard[i][j]); 
       opponentBoard[i][j].setLocation(i + i * SQ_SIZE, j + j * SQ_SIZE); 
       opponentBoard[i][j].setSize(new Dimension(SQ_SIZE, SQ_SIZE)); 
       opponentBoard[i][j].setVisible(true); 
       if ((i == 0)^(j == 0)) { 
        opponentBoard[i][j].setBackground(Color.GRAY); 
        if (i == 0) { 
         coordLabels[j - 1] = new JLabel((char) (j + 64) + ""); 
         opponentBoard[i][j].add(coordLabels[j - 1]); 
         System.out.println(j-1); 
        } 
        if (j == 0) { 
         coordLabels[i + 9] = new JLabel(i + ""); 
         System.out.println(i + 9 + " " + i + " " + coordLabels[i + 9].getText()); 
         opponentBoard[i][j].add(coordLabels[i + 9]); 
        } 
        //opponentBoard[i][j].repaint(); 
       } else { 
        opponentBoard[i][j].setBackground(Color.DARK_GRAY); 
       } 
      } 
     } 
     opponentBoard[0][0].setBackground(Color.BLACK); 

     // If the UI is already visible call validate 
     // I've chose to not make the frame visible until all of the children 
     // have been added so the call to validate isn't really needed. 
     //container.validate(); 
     frame.setVisible(true); 
    } 

    public static void main(String[] args){ 
     new Foo(); 
    } 
}