我正在创建一个游戏，其中从文本文件中提取问题，并将问题设置到JTextArea中。每个问题的答案都在文本文件中，并且用户应将给定问题的答案输入文本字段。从文本文件中提取问题时，无论何时我输入任何内容都不一定是答案，都会弹出一堆错误。
// 4/28/2019
// GamePanel.java
import java.awt.BorderLayout; // import everything needed
import java.awt.Color;
import java.awt.Graphics;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.CardLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.AdjustmentEvent;
import java.awt.event.AdjustmentListener;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.JTextArea;
import javax.swing.JSlider;
import javax.swing.JButton;
import javax.swing.ButtonGroup;
import javax.swing.JRadioButton;
import javax.swing.JCheckBox;
import javax.swing.JLabel;
import javax.swing.JScrollBar;
import javax.swing.Timer;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.util.Scanner;
import java.io.PrintWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
// This panel is the panel which has the game. It is mainly based off of graphics.
// It creates a clown which is juggling balls, and also the background is drawn
// and it is all animated. It also has a TextArea-which displays the question
// and a TextField- which is for the user to type in their answer
public class GamePanel extends JPanel implements ActionListener
{
private CardPanel cp; // instance of CardPanel from the class 'StartPanel'
// to use to switch between cards
private CardLayout cards; // instance of cardLayout
private Timer timer; //Timer for animation
private int counter; // counter for animating arms
private Color colors[]; // array for holding different colors
private int colorCounter; // counter for animating balls
private Scanner questionReader;
private Scanner answerReader;
private String questions[];
private String answers[];
private String question;
private String answer;
private int random;
private String num;
private int numQuestion;
private int numAnswer;
// this panel is also the holder panel- it holds the question TextArea and
// the TextField which the answer is supposed to be typed into
public GamePanel(CardPanel cpIn, CardLayout cardsIn)
{
questions = new String[25];
answers = new String[25];
answer = new String(" ");
question = new String(" ");
cards = cardsIn;
cp = cpIn;
QuestionTA qta = new QuestionTA();
qta.setBounds(300, 35, 400,100);
add(qta);
AnswerTF atf = new AnswerTF();
atf.setBounds(375, 150, 250, 50);
add(atf);
BackButtonPanel bbp = new BackButtonPanel();
bbp.setBounds(600,250,100,200);
add(bbp);
setLayout(null); // this panel is a null layout
Color color = new Color(217, 217, 253);
setBackground(color);
timer = new Timer(25, this);
counter = 2;
colorCounter = 5;
}
public static void main(String[] args)
{
}
}
// this class creates the TextArea which contains the text area, which
// will show all the question that needs to be answered
class QuestionTA extends JPanel
{
private JTextArea questionArea; // the JTextArea which will show the question
private String inFileName;
public QuestionTA()
{
questionArea = new JTextArea("");
questionArea.setPreferredSize(new Dimension(400,400));
questionArea.setEditable(false);
questionArea.setLineWrap(true);
add(questionArea);
getQuestions();
}
public void getQuestions()
{
inFileName= new String("easyequations.txt");
File inFile = new File(inFileName);
try
{
questionReader = new Scanner(inFile);
}
catch(FileNotFoundException e)
{
System.err.println(inFileName + " not found.");
System.exit(1);
}
while(questionReader.hasNext())
{
int random = (int)(Math.random()*25 + 1);
String line = questionReader.nextLine();
num = line.charAt(0) + "";
numQuestion = Integer.parseInt(num);
if(random == numQuestion)
{
questionArea.setText(line);
}
}
}
}
// this class creates the text field which the user will type the answer into
// based on the question shown in the text area. We haven't set up the
// question and answer logic yet in this draft.
class AnswerTF extends JPanel implements ActionListener
{
private JTextField answer;
private int parsedAnswerNum; private String line;
private String wholeFile;
private String realAnswer;
String answered;
public AnswerTF()
{
answer = new JTextField("Enter the answer");
answer.addActionListener(this);
getAnswers();
add(answer);
answered = "";
}
public void getAnswers()
{
int numberOfA = numQuestion;
String inFileAnswers = new String("easysolutions.txt");
File answerFile = new File(inFileAnswers);
try
{
answerReader = new Scanner(answerFile);
}
catch(FileNotFoundException e)
{
System.err.println("Could not read from " + inFileAnswers);
System.exit(1);
}
while(answerReader.hasNext())
{
String line = new String(answerReader.nextLine());
if(line.indexOf(numberOfA) != -1)
{
System.out.println(line);
realAnswer = line;
}
}
}
public void actionPerformed(ActionEvent evt)
{
if(evt.getSource() == answer)
{
answered = answer.getText();
if(answered.equals( realAnswer.substring( (realAnswer.indexOf(" ") + 1), realAnswer.length()-1 )))
{
System.out.println("you are corect");
}
}
}
}
class BackButtonPanel extends JPanel implements ActionListener
{
private JButton goBack;
private QuestionTA qta;
public BackButtonPanel()
{
goBack = new JButton("Return Home");
goBack.addActionListener(this);
add(goBack);
qta = new QuestionTA();
}
public void actionPerformed(ActionEvent evt)
{
if(evt.getActionCommand().equals("Return Home"))
{
cards.show(cp, "home");
qta.getQuestions();
}
}
}
}
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at GamePanel$AnswerTF.actionPerformed(GamePanel.java:403)
at java.desktop/javax.swing.JTextField.fireActionPerformed(JTextField.java:508)
at java.desktop/javax.swing.JTextField.postActionEvent(JTextField.java:723)
at java.desktop/javax.swing.JTextField$NotifyAction.actionPerformed(JTextField.java:839)
at java.desktop/javax.swing.SwingUtilities.notifyAction(SwingUtilities.java:1810)
at java.desktop/javax.swing.JComponent.processKeyBinding(JComponent.java:2900)
at java.desktop/javax.swing.JComponent.processKeyBindings(JComponent.java:2948)
at java.desktop/javax.swing.JComponent.processKeyEvent(JComponent.java:2862)
at java.desktop/java.awt.Component.processEvent(Component.java:6366)
at java.desktop/java.awt.Container.processEvent(Container.java:2261)
at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:4966)
at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2319)
at java.desktop/java.awt.Component.dispatchEvent(Component.java:4798)
at java.desktop/java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1950)
at java.desktop/java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:871)
at java.desktop/java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:1140)
at java.desktop/java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:1010)
at java.desktop/java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:836)
at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:4847)
at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2319)
at java.desktop/java.awt.Window.dispatchEventImpl(Window.java:2772)
at java.desktop/java.awt.Component.dispatchEvent(Component.java:4798)
at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:772)
at java.desktop/java.awt.EventQueue.access$600(EventQueue.java:97)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:721)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:715)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:97)
at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:745)
at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:743)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:742)
at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)
错误在底部。我的预期结果是，只要用户输入正确的答案，终端就会打印“好作业”。我希望这些错误出现在“ QuestionTA”类的“ getQuestions”方法中，并且 “ AnswerTF”类中的“ getAnswers” +“ actionPerformed”方法。这两类都接近最低水平。请问我是否要标记用于分析错误的方法。