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线程 "main"java.lang.NullPointerException 七人骰子游戏中的 JAVA 异常

转载 作者:行者123 更新时间:2023-11-29 06:38:53 26 4
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我正在编写一个模拟骰子游戏“七人制”的 Java GUI。

我已经编写了创建 GUI 的主要部分。

我还没有编写真正玩游戏的程序的实际部分。

一切都正确编译,但我收到运行时错误:

Exception in thread "main" java.lang.NullPointerException
at java.awt.Container.addImpl(Unknown Source)
at java.awt.Container.add(Unknown Source)
at SevensGameGUI.,init.(SevensGameGUI.java:88)
at SeventsApplication.main(SevensApplication.java:13)

我不确定是什么导致了错误?

这是 SevensGameGUI.java 的代码:

//include these import statements in every GUI class
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class SevensGameGUI extends JFrame {

//Instance Variables
// declares an array of integers to store the total score for each player
// allocates memory for 5 players
int[] totalScoreArray = new int[4];

//declares an array of integers to store numbers rolled each time someone rolls the dice
//allocates memory for at least 3 rolls
int[] diceRollArray= new int[2];

//declare an integer amount for the number of dice being rolled in the current turn
int diceCount;

//declare an integer to keep track of track of who the current player is
int playerNumber;

//declare a constant for the maximum throws allowed (three)
public static final int MAX_THROWS = 3;

//declare an integer to remember how many times the first player rolled the dice
int firstPlayerRolls;

//declare an integer to keep count of the current player's rolls
int currentPlayerRolls;

//declare an integer to keep track of who is currently winning
int winningPlayer;

//declare all necessary GUI-related variables
//JButtons:
private JButton rollDiceButton;
private JButton totalScoreButton;
private JButton endTurnButton;

//JLabels:
private JLabel displayCurrentPlayerLabel;
private JLabel displayFirstPlayerRollsLabel;
private JLabel displayTotalScoreLabel;

//JTextAreas:
private JTextArea outputCurrentPlayerTextArea;
private JTextArea outputFirstPlayerRollsTextArea;
private JTextArea outputTotalScoreTextArea;
private JTextArea outputDiceRollTextArea;
private JTextArea outputTextArea;

//JPanels:
private JPanel labelPanel;
private JPanel buttonPanel;


//Declare an event-listener object of type SevensGameListener
SevensGameListener listener;

//---------------------------------------------------------------------------------------------

//CONSTRUCTOR
public SevensGameGUI() {
super("Sevens Dice Game");

//Initialize Buttons:
rollDiceButton = new JButton("Roll Dice");
totalScoreButton = new JButton("Total Your Score");
endTurnButton = new JButton("End Turn");

//Initialize Labels:
displayCurrentPlayerLabel = new JLabel("Current Player: ");
displayFirstPlayerRollsLabel = new JLabel("First player only rolled: ");
displayTotalScoreLabel = new JLabel("Total Score: ");

//Initialize Panels:
labelPanel = new JPanel();
labelPanel.setLayout(new GridLayout(3,2));
labelPanel.add(displayCurrentPlayerLabel);
labelPanel.add(outputCurrentPlayerTextArea);
labelPanel.add(displayFirstPlayerRollsLabel);
labelPanel.add(outputFirstPlayerRollsTextArea);
labelPanel.add(displayTotalScoreLabel);
labelPanel.add(outputTotalScoreTextArea);

buttonPanel = new JPanel();
buttonPanel.setLayout(new GridLayout(1,3));
buttonPanel.add(rollDiceButton);
buttonPanel.add(totalScoreButton);
buttonPanel.add(endTurnButton);

//Set The Layout as Border Layout
this.setLayout(new BorderLayout());
this.add(labelPanel, BorderLayout.NORTH);
this.add(outputTextArea, BorderLayout.CENTER);
this.add(buttonPanel, BorderLayout.SOUTH);

//initilize/register Listener
listener = new SevensGameListener();

rollDiceButton.addActionListener(listener);
totalScoreButton.addActionListener(listener);
endTurnButton.addActionListener(listener);

this.addWindowListener(listener);

}//end of constructor

//---------------------------------------------------------------------------------------------

private class SevensGameListener implements ActionListener, WindowListener {

public void actionPerformed(ActionEvent ae) {

if (ae.getSource() == rollDiceButton) {

}
if (ae.getSource() == totalScoreButton) {

}
if (ae.getSource() == endTurnButton) {
playerNumber += 1;
}


outputTextArea.append(" ");

}//end of method actionPerformed

public void windowClosing(WindowEvent we) {

System.exit(0);

}//end of windowClosing

public void windowDeactivated(WindowEvent we) { }
public void windowActivated(WindowEvent we) { }
public void windowClosed(WindowEvent we) { }
public void windowDeiconified(WindowEvent we) { }
public void windowIconified(WindowEvent we) { }
public void windowOpened(WindowEvent we) { }



}//end of class CalculatorListener


}// end of SevensGameGUI class

而真正运行程序的Application类是

public class SevensApplication {

public static void main (String[] args) {

SevensGameGUI gui = new SevensGameGUI();
gui.pack();
gui.setVisible(true);

}

}

我不确定我是否只是没有完成部分 GUI 部分来实际运行游戏,或者我的代码是否有错误?即使我还没有玩游戏的代码,它会影响我制作的gui的显示吗?

最佳答案

您还没有初始化任何 TextArea

喜欢和检查其他人。

labelPanel.add(outputCurrentPlayerTextArea);

像这样初始化。

outputCurrentPlayerTextArea = new TextArea("Hello", 5, 40);

并为其他人做TextArea

关于线程 "main"java.lang.NullPointerException 七人骰子游戏中的 JAVA 异常,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/15528271/

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