使用NullPointerException使用KeyListener使用setText时
使用NullPointerException使用KeyListener使用setText时
提问于 2014-03-07 18:05:57
这是猜字游戏。第一个字母每次都显示出来，而他们没有休息。每当用户输入我希望它更改板上字母的时候，下面是一个屏幕截图：http://puu.sh/7moQS.jpg
错误：
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at BoardUI.keyTyped(BoardUI.java:48)行BoardUI.java:48在哪里
b.getLetters()[b.position(b.getCurrentRow(), b.getCurrentColumn())].setText(typed + "");
Game.java
public class Game {
}testGUI.java
public class testGUI {
public static void main(String[] args) {
new GUI("Lingo");
}
}BoardUI.java
import javax.swing.*;
import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
public class BoardUI extends JPanel implements KeyListener {
private final Game game;
private Board b = new Board();
private Color hoverColor = new Color(100, 100, 255);
public BoardUI(LayoutManager layout, Game game, String word) {
super(layout);
this.b = new Board();
this.game = game;
initComponents(word);
}
public BoardUI(Game game) {
this.game = game;
}
private void initComponents(String word) {
this.setLayout(new GridLayout(5, 5, 2, 2));
for (int i = 0; i < 5 * 5; i++) {
b.getLetters()[i] = new Label();
b.getLetters()[i].setBackground(Color.WHITE);
b.getLetters()[i].setForeground(Color.BLACK);
b.getLetters()[i].setAlignment(Label.CENTER);
b.getLetters()[i].setFont(new Font("Big", Font.BOLD, 48));
this.add(b.getLetters()[i]);
}
for (int i = 0; i < 5; i++) {
b.getLetters()[i].setText(word.charAt(i) + "");
b.getLetters()[i].setBackground(Color.BLUE);
}
b.setCurrentColumn(0);
b.setCurrentRow(0);
}
@Override
public void keyTyped(KeyEvent e) {
char typed = e.getKeyChar();
if (Character.isLetter(typed) && b.getCurrentColumn() < 5) {
typed = Character.toUpperCase(typed);
b.getLetters()[b.position(b.getCurrentRow(), b.getCurrentColumn())].setText(typed + "");
b.getLetters()[b.position(b.getCurrentRow(), b.getCurrentColumn())].setBackground(Color.BLUE);
if (b.getCurrentColumn() == 0) {
for (int i = 1; i < 5; i++) {
b.getLetters()[b.position(b.getCurrentRow(), i)].setText(".");
b.getLetters()[b.position(b.getCurrentRow(), i)].setBackground(Color.BLUE);
}
b.nextColumn(true);
if (b.getCurrentColumn() < 5) {
b.getLetters()[b.position(b.getCurrentRow(), b.getCurrentColumn())].setBackground(hoverColor);
}
if (typed == 8 && b.getCurrentColumn() >= 0) {
this.oneBack();
}
}
}
}
private void oneBack() {
if (b.getCurrentColumn() < 5) {
b.getLetters()[b.position(b.getCurrentRow(), b.getCurrentColumn())].setBackground(Color.BLUE);
b.nextColumn(false);
b.getLetters()[b.position(b.getCurrentRow(), b.getCurrentColumn())].setText(".");
b.getLetters()[b.position(b.getCurrentRow(), b.getCurrentColumn())].setBackground(Color.BLUE);
}
}
@Override
public void keyPressed(KeyEvent e) {
}
@Override
public void keyReleased(KeyEvent e) {
}
}Board.java：
import java.awt.*;
public class Board {
private Reader reader = new Reader();
private Label[] letters = new Label[5 * 5];
private String[] words = new String[100];
private int currentRow, currentColumn;
public Label[] getLetters() {
return letters;
}
public String firstWord() {
return getWord().charAt(0) + "....";
}
public String getWord() {
int count = reader.LeesWoordenVanFile(words);
int x = (int) (Math.random() * 100);
int gokX = (x % count);
return words[gokX].toUpperCase();
}
public int position(int row, int column) {
return row * 5 + column;
}
public void nextColumn(boolean next) {
if (next) {
currentColumn++;
} else {
currentColumn--;
}
}
public int getCurrentRow() {
return currentRow;
}
public int getCurrentColumn() {
return currentColumn;
}
public void setCurrentRow(int currentRow) {
this.currentRow = currentRow;
}
public void setCurrentColumn(int currentColumn) {
this.currentColumn = currentColumn;
}
}GUI.java：
import javax.swing.*;
import java.awt.*;
public class GUI extends JFrame {
private JPanel gamePanel;
private Game game;
private Board board = new Board();
private BoardUI boardUI = new BoardUI(game);
public GUI(String title) throws HeadlessException {
super(title);
game = new Game();
setupVieuw();
showFrame();
this.addKeyListener(boardUI);
}
public void setupVieuw() {
getContentPane().removeAll();
initComponents(board.firstWord());
layoutComponents();
this.validate();
}
public void layoutComponents() {
getContentPane().add(gamePanel, BorderLayout.CENTER);
}
private void initComponents(String word) {
gamePanel = new JPanel(new BorderLayout());
gamePanel.add(new BoardUI(new BorderLayout(),game, word));
}
private void showFrame() {
this.setBounds(50, 50, 800, 800);
this.setPreferredSize(new Dimension(600, 600));
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.pack();
this.setVisible(true);
this.doLayout();
}
}回答 1
Stack Overflow用户
回答已采纳
发布于 2014-03-07 18:49:32
这非常令人困惑，因为您有一些多余的代码，并且在某些情况下执行了两次，但是下面是我所发现的。
在GUI.java中，您在这里实例化BoardUI：
private Game game;
private Board board = new Board();
private BoardUI boardUI = new BoardUI(game);注意到，
- 您正在使用空的
BoardUI对象来初始化Game - 您正在调用这个
BoardUI构造函数： 公共BoardUI(游戏游戏){ this.game =对策；} 而不是这个构造器--也就是。实际上用letters对象填充new Label()数组的方法： 公共BoardUI(LayoutManager布局，游戏游戏，字符串词){超级(布局)；this.b .b=新板()；this.game =游戏；initComponents( word)；}
仍然在GUI.java中，您最终会调用一个不同的initComponents()，但是使用一个新的BoardUI实例来调用它
private void initComponents(String word) {
gamePanel = new JPanel(new BorderLayout());
gamePanel.add(new BoardUI(new BorderLayout(),game, word));
}在返回之后，回到GUI类构造函数的最后一行，并将键侦听器设置为未运行initComponents()的BoardUI
this.addKeyListener(boardUI);TL;DR:您正在向没有运行BoardUI的initComponents()对象中添加一个键侦听器
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/22257495
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