我已经对这些类型的错误进行了一些搜索，但仍然无法弄清楚我做错了什么。我的小程序无法启动/初始化。弹出小程序窗口，然后说开始：小程序未在底部初始化。
以下是错误：
java.lang.NullPointerException at randomquotegenerator.quote.init(quote.java:170) at sun.applet.AppletPanel.run(AppletPanel.java:424) at java.lang.Thread.run(Thread.java:619)
作为quote.java:170错误返回的行在init（）部分中：
readLines(quoteFiles[0].getName());
我有7个带引号的文本文件，每行一个，第一行是引号的标题。每行都用双引号“”包围。
//****************************************************************************
//****************************************************************************
//** Imports **
//****************************************************************************
package randomquotegenerator;
import java.io.*;
import java.lang.*;
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import javax.swing.*;
//****************************************************************************
//** Class Definination **
//****************************************************************************
public class quote extends JApplet implements ActionListener,Runnable
{
//****************************************************************************
//** Class Global Variables **
//****************************************************************************
int randomLine=0,maxLines=0,maxFiles=0,quoteLine=0,quoteFile=0;
int doneFiles[] =new int[100];
int doneLines[] =new int[200];
int randomSwitch=-1,linearSwitch=-1;
int TimeDelay=0,TimeWait=1;
int currentFile=0,currentLine=0,unreadLines=0,unreadFiles=0;
//int randomFile,randomLine;
File path=new File("quotes\\");
File[] quoteFiles=path.listFiles();
Thread thread;
Panel northPanel=new Panel();
Panel centerPanel=new Panel();
Panel southPanel=new Panel(new GridLayout(1,0));
Panel Labels = new Panel(new GridLayout(0,1));
Panel ListBox1 = new Panel(new GridLayout(1,0));
Panel ListBox2 = new Panel(new GridLayout(1,0));
Panel ButtonSet1 = new Panel(new GridLayout(3,2));
Panel ButtonSet2 = new Panel(new GridLayout(0,1));
JLabel lab1=new JLabel("Quote Files");
JLabel lab2=new JLabel("Current File");
JLabel lab3=new JLabel("Quote Lines ");
JLabel lab4=new JLabel("Current Line");
JLabel lab5=new JLabel("TimeDelay ");
JLabel lab6=new JLabel(" ");
JLabel lab7=new JLabel(" ");
List FilesList=new List(7);
List LinesList=new List(7);
JTextArea quoteDisplay= new JTextArea(18,36);
JLabel quoteTitle = new JLabel("Java Applet Random Quote Displayer");
Button PrevLine=new Button("Prev Line");
Button NextLine=new Button("Next Line");
Button PrevFile=new Button("Prev File");
Button NextFile=new Button("Next File");
Button ResetLine=new Button("Reset Lines");
Button ResetFile=new Button("Reset Files");
Button Settings=new Button("Settings ");
Button NullButton1=new Button(" ");
Button LinearButton=new Button("Linear Mode");
Button RandomButton=new Button("Random Mode");
Button ExitButton=new Button("Exit");
boolean done=false;
//String s=new String;;
String lines[]=new String[200];
//****************************************************************************
//** Inititialize
//****************************************************************************
@Override
public void init(){
setSize(768, 500);
setLayout(new BorderLayout());
add("North",northPanel);
northPanel.setBackground(Color.blue);
add("Center",centerPanel);
centerPanel.setBackground(Color.black);
add("South",southPanel);
southPanel.setBackground(new Color(64,64,64));
northPanel.setBackground(new Color(64,64,64));
Labels.add(lab1);
Labels.add(lab2);
Labels.add(lab3);
Labels.add(lab4);
Labels.add(lab5);
Labels.add(lab6);
Labels.add(lab7);
ListBox1.add(FilesList);
ListBox2.add(LinesList);
ButtonSet1.add(PrevLine);
ButtonSet1.add(NextLine);
ButtonSet1.add(PrevFile);
ButtonSet1.add(NextFile);
ButtonSet1.add(ResetLine);
ButtonSet1.add(ResetFile);
//ButtonSet1.add(Settings);
//ButtonSet1.add(NullButton1);
ButtonSet2.add(LinearButton);
ButtonSet2.add(RandomButton);
ButtonSet2.add(ExitButton);
southPanel.add(Labels);
southPanel.add(ListBox1);
southPanel.add(ListBox2);
southPanel.add(ButtonSet1);
southPanel.add(ButtonSet2);
centerPanel.add(quoteDisplay);
northPanel.add(quoteTitle);
//quoteDisplay.setColor(new Color(255,255,255));
FilesList.addActionListener(this);
LinesList.addActionListener(this);
PrevLine.addActionListener(this);
NextLine.addActionListener(this);
PrevFile.addActionListener(this);
NextFile.addActionListener(this);
ResetLine.addActionListener(this);
ResetFile.addActionListener(this);
Settings.addActionListener(this);
//NullButton1.addActionListener(this);
LinearButton.addActionListener(this);
RandomButton.addActionListener(this);
ExitButton.addActionListener(this);
Font font=new Font("times",Font.BOLD,24);
quoteDisplay.setFont(font);
quoteDisplay.setEditable(false);
quoteDisplay.setLineWrap(true);
quoteDisplay.setWrapStyleWord(true);
Font font2=new Font("times",Font.BOLD,16);
quoteTitle.setFont(font2);
listFiles();
readLines(quoteFiles[0].getName());
FilesList.select(0);
LinesList.select(0);
TimeDelay=lines[0].length()*TimeWait;
unreadFiles=maxFiles;
unreadLines=maxLines;
currentFile=0;
currentLine=0;
done=false;
//maxLines=10;
creatRandomFiles();
creatRandomLines();
lab1.setText("quote Files = "+maxFiles);
lab2.setText("File = "+quoteFiles[0].getName());
lab3.setText("quote Lines = "+maxLines);
lab4.setText("Current Line = "+quoteLine);
lab5.setText("TimeDelay = "+TimeDelay);
lab6.setText("Lines Unread "+unreadLines);
lab7.setText("Files Unread "+unreadFiles);
JOptionPane.showMessageDialog(null, " By Erin");
}
//*********************************************
//* *
//*********************************************
public void creatRandomFiles()
{
for (int i=0;i<maxFiles;i++)
{
doneFiles[i]=(int)(Math.random()*maxFiles);
for(int j=0;j<i;j++) if (doneFiles[j]==doneFiles[i]) i--;
//System.out.println("maxLines = "+doneLines[i]+"");
}
}
//*********************************************
//* *
//*********************************************
public void creatRandomLines()
{
for (int i=0;i<maxLines;i++)
{
doneLines[i]=(int)(Math.random()*maxLines);
for(int j=0;j<i;j++) if (doneLines[j]==doneLines[i]) i--;
//System.out.println("maxLines = "+doneLines[i]+"");
}
}
//*********************************************
//* *
//*********************************************
public void runLinearLines()
{
while(currentLine<maxLines)
{
quoteLine=currentLine;
selectLine();
TimeDelay=lines[quoteLine].length()*TimeWait;
unreadLines=maxLines-currentLine;
lab5.setText("TimeDelay = "+TimeDelay);
lab6.setText("Lines Unread "+unreadLines);
currentLine++;
System.out.println("Line Data: "+ (currentLine+1)+ ". Line= "+doneLines[currentLine]+ ", Unread= "+ unreadLines+" ,time=" +TimeDelay+" ms");
try {thread.sleep(TimeDelay);}
catch (Exception exception){}
}
currentLine=0;
quoteLine=0;
unreadLines=maxLines-currentLine;
currentFile++;
unreadFiles=maxFiles-currentFile;
quoteFile=currentFile;
FilesList.select(quoteFile);
//FilesList.makeVisible(quoteFile);
readLines(quoteFiles[FilesList.getSelectedIndex()].getName());
lab6.setText("Lines Unread "+unreadLines);
lab2.setText("File = "+quoteFiles[FilesList.getSelectedIndex()].getName());
lab7.setText("Files Unread "+unreadFiles);
System.out.println("-------------------------------------------------------------");
System.out.println("File Data: "+ (currentFile+1)+ ", " + quoteFiles[FilesList.getSelectedIndex()].getName()+". File= "+doneFiles[currentFile]+" ,time=" +TimeDelay+" ms");
System.out.println("-------------------------------------------------------------");
if (unreadFiles<0)
{
currentFile=0;
currentLine=0;
}
}
//*********************************************
//* *
//*********************************************
public void runRandomLines()
{
//currentLine=0;
while(currentLine<maxLines)
{
quoteLine=doneLines[currentLine];
selectLine();
TimeDelay=lines[quoteLine].length()*TimeWait;
unreadLines=maxLines-currentLine;
lab5.setText("TimeDelay = "+TimeDelay);
lab6.setText("Lines Unread "+unreadLines);
currentLine++;
System.out.println("Line Data: "+ (currentLine+1)+ ". Line= "+doneLines[currentLine]+ ", Unread= "+ unreadLines+" ,time=" +TimeDelay+" ms");
try {thread.sleep(TimeDelay);}catch (Exception exception){}
}
currentLine=0;
quoteLine=0;
unreadLines=maxLines-currentLine;
currentFile++;
unreadFiles=maxFiles-currentFile;
quoteFile=doneFiles[currentFile];
FilesList.select(quoteFile);
//FilesList.makeVisible(quoteFile);
for (int i=0;i<200;i++) doneLines[i]=0;
creatRandomLines();
readLines(quoteFiles[FilesList.getSelectedIndex()].getName());
lab6.setText("Lines Unread "+unreadLines);
lab2.setText("File = "+quoteFiles[FilesList.getSelectedIndex()].getName());
lab7.setText("Files Unread "+(unreadFiles+1));
System.out.println("-------------------------------------------------------------");
System.out.println("File Data: "+ (currentFile+1)+ ", " + quoteFiles[FilesList.getSelectedIndex()].getName()+". File= "+doneFiles[currentFile]+" ,time=" +TimeDelay+" ms");
System.out.println("-------------------------------------------------------------");
if (unreadFiles<0)
{
for (int i=0;i<100;i++) doneFiles[i]=0;
for (int i=0;i<200;i++) doneLines[i]=0;
creatRandomFiles();
creatRandomLines();
currentFile=0;
currentLine=0;
}
//System.out.println("------------------------------");
}
//****************************************************************************
//** Paint **
//****************************************************************************
@Override
public void paint(Graphics g)
{
}
//****************************************************************************
//** Thread **
//****************************************************************************
@Override
public void start()
{
thread = new Thread(this);
thread.start();
}
@Override
synchronized public void run()
{
while (true)
{
//*********************************************
//* *
//*********************************************
if (randomSwitch==1)
{
creatRandomLines();
runRandomLines();
}
if (linearSwitch==1)
{
runLinearLines();
}
}
}
@Override
public void stop()
{
if (thread != null) thread.stop();
}
//****************************************************************************
//** actionPerformed **
//****************************************************************************
public void selectFile()
{
for (int i=0;i<200;i++) doneLines[i]=0;
FilesList.select(quoteFile);
//FilesList.makeVisible(quoteFile);
readLines(quoteFiles[FilesList.getSelectedIndex()].getName());
lab2.setText("File = "+quoteFiles[FilesList.getSelectedIndex()].getName());
}
//*********************************************
//* *
//*********************************************
public void selectLine()
{
LinesList.select(quoteLine);
//LinesList.makeVisible(quoteLine);
quoteDisplay.setText(lines[LinesList.getSelectedIndex()]);
lab4.setText("Current Line = "+(quoteLine+1));
TimeDelay=lines[quoteLine].length()*TimeWait;
lab5.setText("TimeDelay = "+TimeDelay);
}
//*********************************************
//* *
//*********************************************
@Override
public boolean keyDown(Event event, int key)
{
switch(key)
{
case 10:
//enter
break;
case 32:
//space
break;
case 27:
//esc
System.exit(0);
break;
case 1006:
//left
done=true;
quoteLine=0;
quoteFile--;if (quoteFile<1) quoteFile=0;
selectFile();
selectLine();
break;
case 1007:
//right
done=true;
quoteLine=0;
quoteFile++;if (quoteLine>maxFiles) quoteFile=maxFiles;
selectFile();
selectLine();
break;
case 1004:
//up
quoteLine--;if (quoteLine<1) quoteLine=0;
selectLine();
break;
case 1005:
//down
quoteLine++;if (quoteLine>maxLines) quoteLine=maxLines;
selectLine();
break;
}
showStatus("(key= "+key+") ");
return false;
}
//*********************************************
//* *
//*********************************************
@Override
public void actionPerformed(ActionEvent event)
{
if (event.getSource()==ExitButton)
{
//System.exit(0);
}
if (event.getSource()==LinesList)
{
quoteLine=LinesList.getSelectedIndex();
showStatus(FilesList.getSelectedItem()+" " +LinesList.getSelectedItem()+ " "+ LinesList.getSelectedIndex());
quoteDisplay.setText(lines[LinesList.getSelectedIndex()]);
lab4.setText("Current Line = "+(quoteLine+1));
//quoteTitle.setText(lines[LinesList.getSelectedIndex()]);
}
if (event.getSource()==FilesList)
{
quoteFile=FilesList.getSelectedIndex();
lab2.setText("File = "+quoteFiles[FilesList.getSelectedIndex()].getName());
showStatus(FilesList.getSelectedItem()+" " +LinesList.getSelectedItem()+ " "+ LinesList.getSelectedIndex());
readLines(quoteFiles[FilesList.getSelectedIndex()].getName());
quoteLine=0;
//selectFile();
selectLine();
}
if (event.getSource()==PrevLine)
{
quoteLine--;if (quoteLine<1) quoteLine=0;
selectLine();
}
if (event.getSource()==NextLine)
{
quoteLine++;if (quoteLine>maxLines) quoteLine=maxLines;
selectLine();
}
if (event.getSource()==PrevFile)
{
done=true;
quoteLine=0;
quoteFile--;if (quoteFile<1) quoteFile=0;
selectFile();
selectLine();
}
if (event.getSource()==NextFile)
{
done=true;
quoteLine=0;
quoteFile++;if (quoteLine>maxFiles) quoteFile=maxFiles;
selectFile();
selectLine();
}
if (event.getSource()==ResetLine)
{
quoteLine=0;
quoteFile=0;
selectFile();
selectLine();
}
if (event.getSource()==ResetFile)
{
quoteLine=0;
quoteFile=0;
selectFile();
selectLine();
}
if (event.getSource()==LinearButton)
{
linearSwitch=-linearSwitch;
if (linearSwitch==1)
{
randomSwitch=-1;
LinearButton.setLabel("Linear Off ");
RandomButton.setLabel("Random On");
}
else
{
LinearButton.setLabel("Linear On");
}
System.out.println("linearSwitch = " + linearSwitch+", randomSwitch= "+randomSwitch);
}
if (event.getSource()==RandomButton)
{
randomSwitch=-randomSwitch;
if (randomSwitch==1)
{
linearSwitch =-1;
RandomButton.setLabel("Random Off ");
LinearButton.setLabel("Linear On");
}
else
{
RandomButton.setLabel("Random On");
}
System.out.println("linearSwitch = " + linearSwitch+", randomSwitch= "+randomSwitch);
}
if (event.getSource()==ExitButton)
{
System.exit(0);
}
}
//*********************************************
//* *
//*********************************************
public void readLines(String fileName)
{
DataInputStream inStream;
int count=0;
LinesList.removeAll();
try {
inStream = new DataInputStream(
new FileInputStream("quotes\\"+fileName));
while ( inStream.available() > 0 )
{
lines[count]=inStream.readLine();
if (count==0)
{
quoteTitle.setText(lines[count]);
quoteDisplay.setText(lines[count]);
}
LinesList.add((count+1) + "");
// System.out.println( lines[count]);
count++;
} // End while.
maxLines=count;
lab3.setText("quote Lines = "+maxLines);
inStream.close();
} catch ( java.io.IOException exception)
{
if ( exception instanceof FileNotFoundException)
{
System.out.println(
"A file called test.txt could not be found, \n" +
"or could not be opened.\n" +
"Please investigate and try again.");
}
}
}
//*********************************************
//* *
//*********************************************
public void listFiles()
{
int i;
maxFiles=0;
if (quoteFiles !=null)
{
for (i=0;i<quoteFiles.length;i++)
{
// System.out.println(" "+i +" " + quoteFiles[i]);
FilesList.add(quoteFiles[i].getName());
maxFiles++;
}
lab1.setText("quote Files = "+maxFiles);
}
}
//****************************************************************************
//** **
//****************************************************************************
}
答案 0 :(得分：0)
File path=new File("quotes\\");
File[] quoteFiles=path.listFiles();
路径可能会返回null。
尝试声明它，然后在init（）中初始化它。
如果它为null，那么quoteFiles将为空，因为listFiles（）很可能有一个catch，因此path将为null。
告诉我这是否有帮助：D
Firexranger8