我对这个优越的网站感到非常惊讶！
我的目标是获取.txt文件，将其读入，根据选择的“windowsize”（由jcombobox选择多少个字符）将其剪切为单个字符串并按频率列出。 通过调试，它会停止标记注释的位置。 我无法消除那些被抛出的异常：
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at xxxx.Babbles_GUI.windowSize(Babbles_GUI.java:247) at
xxxx.Babbles_GUI.actionPerformed(Babbles_GUI.java:203) at
javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2028)
at
javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2351)
at
javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
at
javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
at
javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
at java.awt.Component.processMouseEvent(Component.java:6375) at
javax.swing.JComponent.processMouseEvent(JComponent.java:3267) at
java.awt.Component.processEvent(Component.java:6140) at
java.awt.Container.processEvent(Container.java:2083) at
java.awt.Component.dispatchEventImpl(Component.java:4737) at
java.awt.Container.dispatchEventImpl(Container.java:2141) at
java.awt.Component.dispatchEvent(Component.java:4565) at
java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4619)
at
java.awt.LightweightDispatcher.processMouseEvent(Container.java:4280)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4210)
at java.awt.Container.dispatchEventImpl(Container.java:2127) at
java.awt.Window.dispatchEventImpl(Window.java:2482) at
java.awt.Component.dispatchEvent(Component.java:4565) at
java.awt.EventQueue.dispatchEventImpl(EventQueue.java:684) at
java.awt.EventQueue.access$000(EventQueue.java:85) at
java.awt.EventQueue$1.run(EventQueue.java:643) at
java.awt.EventQueue$1.run(EventQueue.java:641) at
java.security.AccessController.doPrivileged(Native Method) at
java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
at
java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:98)
at java.awt.EventQueue$2.run(EventQueue.java:657) at
java.awt.EventQueue$2.run(EventQueue.java:655) at
java.security.AccessController.doPrivileged(Native Method) at
java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:654) at
java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:296)
at
java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:211)
at
java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:201)
at
java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:196)
at
java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:188)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
public class Analysis {
/**
* @param file
*/
public static void analyze(File file, int windowSize) {
ArrayList<String> splittedText = new ArrayList<String>();
System.out.println(windowSize);
StringBuffer buf = new StringBuffer();
if (file.exists()) {
try {
FileInputStream fis = new FileInputStream(file);
InputStreamReader isr = new InputStreamReader(fis,
Charset.forName("UTF-8"));
BufferedReader reader = new BufferedReader(isr);
String line = "";
while ((line = reader.readLine()) != null) {
buf.append(line);
splittedText.add(line);
}
reader.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
String wholeString = buf.toString();
// for (int i = 0; i < wholeString.length(); i += (Babbles_GUI
// .WindowSize())) {
// splittedText.add(wholeString.substring(
// i,
// Math.min(i + (Babbles_GUI.WindowSize()),
// wholeString.length())));
// }
// for (int i = 0; (i < wholeString.length()-(Babbles_GUI.WindowSize())); i += Babbles_GUI.WindowSize()) {
// splittedText.add(wholeString.substring(i, Math.min(Babbles_GUI.WindowSize()+i, wholeString.length())));
// }
for(int i = 0; i<wholeString.length()-(windowSize); i++){
splittedText.add(wholeString.substring(i, i+windowSize));
}
System.out.println("error");
Set<String> unique = new HashSet<String>(splittedText);
for (String key : unique) {
Babbles_GUI.txtAnalysis.append(Collections.frequency(splittedText,
key) + "x " + key + "\t" + "\t");
}
Babbles_GUI.txtLog.append("Text analyzed with WindowSize "
+ windowSize + "\n");
}
}
public class Babbles_GUI extends JFrame implements ActionListener {
private static final long serialVersionUID = 1L;
JFileChooser fc1;
JButton btnFileCh;
JButton btnOutput;
JLabel lblBtnLabel;
static JTextArea txtLog;
static JTextArea txtOrig;
static JTextArea txtAnalysis;
JTextArea txtGenerated;
static JComboBox cbxWindowSize;
BorderLayout borderlayout;
JScrollPane ScrLog;
private JPanel pnWest;
private JPanel pnEast;
private JPanel pnNorth;
private JPanel pnCenter;
private JPanel pnSouth;
static int numberofchars;
public Babbles_GUI(String title) {
this.setTitle(title);
this.setSize(1200, 2400);
this.createUI();
this.setVisible(true);
this.setResizable(false);
this.pack();
this.setLocation(
(Toolkit.getDefaultToolkit().getScreenSize().width - this
.getSize().width) / 2, (Toolkit.getDefaultToolkit()
.getScreenSize().height - this.getSize().height) / 2);
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
}
/**
*
*/
private void createUI() {
btnFileCh = new JButton("Open...");
// btnFileCh.setForeground(Color.BLACK);
btnFileCh.setFont(new Font("Monospaced", Font.PLAIN, 14));
btnFileCh.setPreferredSize(new Dimension(100, 20));
btnFileCh.addActionListener(this);
lblBtnLabel = new JLabel("Number of letters to shuffle: ");
lblBtnLabel.setFont(new Font("Monospaced", Font.BOLD, 14));
lblBtnLabel.setForeground(Color.WHITE);
txtLog = new JTextArea();
txtLog.setBackground(getBackground());
txtLog.setBackground(Color.BLACK);
txtLog.setForeground(Color.WHITE);
txtLog.setWrapStyleWord(true);
txtLog.setLineWrap(true);
txtLog.setFont(new Font("Monospaced", Font.PLAIN, 13));
JScrollPane spTxtlog = new JScrollPane(txtLog);
spTxtlog.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_NEVER);
spTxtlog.setBorder(BorderFactory.createMatteBorder(5, 0, 0, 0,
Color.RED));
txtOrig = new JTextArea();
txtOrig.setEditable(false);
txtOrig.setWrapStyleWord(true);
txtOrig.setLineWrap(true);
txtOrig.setBackground(Color.BLACK);
txtOrig.setForeground(Color.WHITE);
txtOrig.setFont(new Font("Monospaced", Font.PLAIN, 15));
txtOrig.setBorder(BorderFactory.createMatteBorder(10, 0, 0, 0,
Color.BLUE));
txtAnalysis = new JTextArea();
txtAnalysis.setEditable(false);
txtAnalysis.setWrapStyleWord(true);
txtAnalysis.setLineWrap(true);
txtAnalysis.setBackground(Color.BLACK);
txtAnalysis.setForeground(Color.WHITE);
txtAnalysis.setFont(new Font("Monospaced", Font.PLAIN, 15));
txtAnalysis.setBorder(new EmptyBorder(20, 0, 0, 20));
JScrollPane spTxtAn = new JScrollPane(txtAnalysis);
spTxtAn.setBorder(BorderFactory.createMatteBorder(10, 0, 0, 0,
Color.GREEN));
btnOutput = new JButton("Generate");
btnOutput.addActionListener(this);
btnOutput.setForeground(Color.BLACK);
btnOutput.setFont(new Font("Monospaced", Font.PLAIN, 14));
btnOutput.setPreferredSize(new Dimension(100, 20));
String[] item = { "WindowSize 1", "WindowSize 2", "WindowSize 3",
"WindowSize 4", "WindowSize 5", "WindowSize 6", "WindowSize 7" };
JComboBox cbxWindowSize = new JComboBox(item);
cbxWindowSize.setFont(new Font("Monospaced", Font.PLAIN, 14));
cbxWindowSize.setPreferredSize(new Dimension(200, 20));
Box bxLeft = Box.createHorizontalBox();
bxLeft.add(lblBtnLabel);
bxLeft.add(cbxWindowSize);
Box bxCenter = Box.createHorizontalBox();
bxCenter.add(btnFileCh);
Box bxRight = Box.createHorizontalBox();
bxRight.add(btnOutput);
txtGenerated = new JTextArea();
txtGenerated.setEditable(false);
txtGenerated.setBackground(Color.BLACK);
txtGenerated.setForeground(Color.WHITE);
txtGenerated.setBorder(BorderFactory.createMatteBorder(10, 0, 0, 0,
Color.YELLOW));
pnWest = new JPanel();
pnEast = new JPanel();
pnNorth = new JPanel();
pnCenter = new JPanel();
pnSouth = new JPanel();
pnWest.setLayout(new BorderLayout());
pnWest.setBorder(new EmptyBorder(0, 0, 0, 10));
pnWest.setBackground(Color.BLACK);
pnEast.setLayout(new BorderLayout());
pnEast.setBorder(new EmptyBorder(0, 10, 0, 0));
pnEast.setBackground(Color.BLACK);
pnNorth.setLayout(new FlowLayout(FlowLayout.LEFT));
pnNorth.setBackground(Color.BLACK);
pnCenter.setLayout(new BorderLayout());
pnCenter.setBackground(Color.BLACK);
pnSouth.setLayout(new BorderLayout());
try {
this.fc1 = new JFileChooser();
fc1.setFileFilter(new FileNameExtensionFilter(null, "txt"));
} catch (IllegalArgumentException e) {
txtOrig.append("");
txtLog.append("File format must be .txt" + "\n");
}
pnNorth.add(bxLeft);
pnNorth.add(bxCenter);
pnNorth.add(bxRight);
pnSouth.add(spTxtlog, BorderLayout.SOUTH);
pnWest.add(txtOrig, BorderLayout.CENTER);
pnWest.setPreferredSize(new Dimension(400, 700));
pnCenter.add(spTxtAn, BorderLayout.CENTER);
pnCenter.setPreferredSize(new Dimension(400, 700));
pnEast.add(txtGenerated, BorderLayout.CENTER);
pnEast.setPreferredSize(new Dimension(400, 700));
borderlayout = new BorderLayout();
borderlayout.setHgap(30);
borderlayout.setVgap(3);
setBackground(Color.BLACK);
getContentPane().setLayout(borderlayout);
getContentPane().add(pnEast, BorderLayout.EAST);
getContentPane().add(pnWest, BorderLayout.WEST);
getContentPane().add(pnNorth, BorderLayout.NORTH);
getContentPane().add(pnCenter, BorderLayout.CENTER);
getContentPane().add(pnSouth, BorderLayout.SOUTH);
}
@Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == btnFileCh) {
int returnVal = fc1.showOpenDialog(Babbles_GUI.this);
if (returnVal == JFileChooser.APPROVE_OPTION) {
File file = fc1.getSelectedFile();
txtLog.append(file.getName() + " opened" + "\n");
printOrigFile(file);
//DEBUG-STOP**********************************
Analysis.analyze(file, windowSize());
} else {
txtLog.append("Open command cancelled by user" + "\n");
}
txtLog.setCaretPosition(txtLog.getDocument().getLength());
}
}
public static void main(String[] args) {
new Babbles_GUI("Babbles Exercise David Huser");
}
/**
* @param file
* @return
*/
public String printOrigFile(File file) {
StringBuffer buf = new StringBuffer();
if (file.exists()) {
try {
FileInputStream fis = new FileInputStream(file);
InputStreamReader isr = new InputStreamReader(fis,
Charset.forName("UTF-8"));
BufferedReader reader = new BufferedReader(isr);
String line = "";
while ((line = reader.readLine()) != null) {
buf.append(line + "\n");
}
reader.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
txtOrig.setText(buf.toString());
return (buf.toString());
}
public int windowSize() {
if (cbxWindowSize.getSelectedItem().equals("WindowSize 1")) {
numberofchars = 1;
} else if (cbxWindowSize.getSelectedItem().equals("WindowSize 2")) {
numberofchars = 2;
} else if (cbxWindowSize.getSelectedItem().equals("WindowSize 3")) {
numberofchars = 3;
} else if (cbxWindowSize.getSelectedItem().equals("WindowSize 4")) {
numberofchars = 4;
} else if (cbxWindowSize.getSelectedItem().equals("WindowSize 5")) {
numberofchars = 5;
} else if (cbxWindowSize.getSelectedItem().equals("WindowSize 6")) {
numberofchars = 6;
} else if (cbxWindowSize.getSelectedItem().equals("WindowSize 7")) {
numberofchars = 7;
}
return numberofchars;
}
}
答案 0 :(得分：2)
windowSize()中有一个null对象。您确定cbxWindowSize已初始化吗？
另一种可能性是没有选定的项目。在这种情况下，getSelectedItem()将返回null。您需要检查此项，而不是立即在结果上调用equals()。
修改
String[] item = { "WindowSize 1", "WindowSize 2", "WindowSize 3",
"WindowSize 4", "WindowSize 5", "WindowSize 6", "WindowSize 7" };
JComboBox cbxWindowSize = new JComboBox(item);
这定义了一个新的局部变量并对其进行初始化。局部变量隐藏了具有相同名称的类变量。从行的开头删除JComboBox。