我正在尝试从JFileChooser接收一个文件，然后我可以将其传递到我的TextStatistics类中。我似乎无法继续参考该文件...任何帮助将不胜感激。
谢谢！
ProcessText.java：
public class ProcessText extends JPanel implements ActionListener {
static private final String newline = "\n";
JButton openButton;
JButton calculate;
JTextArea log;
JFileChooser fc;
public ProcessText() {
super(new BorderLayout());
log = new JTextArea(5, 20);
log.setMargin(new Insets(5, 5, 5, 5));
log.setEditable(false);
JScrollPane logScrollPane = new JScrollPane(log);
JPanel buttonPanel = new JPanel(); // use FlowLayout
buttonPanel.add(openButton);
buttonPanel.add(calculate);
// Add the buttons and the log to this panel.
add(buttonPanel, BorderLayout.PAGE_START);
add(logScrollPane, BorderLayout.CENTER);
}
public void actionPerformed(ActionEvent e) {
File file = null;
TextStatistics stat = null;
if (e.getSource() == openButton) {
int returnVal = fc.showOpenDialog(ProcessText.this);
if (returnVal == JFileChooser.APPROVE_OPTION) {
file = fc.getSelectedFile();
stat = new TextStatistics(file);
}
}
if (e.getSource() == calculate) {
log.append(stat.toString());
}
}
/** Returns an ImageIcon, or null if the path was invalid. */
protected static ImageIcon createImageIcon(String path) {
java.net.URL imgURL = ProcessText.class.getResource(path);
if (imgURL != null) {
return new ImageIcon(imgURL);
} else {
System.err.println("Couldn't find file: " + path);
return null;
}
}
private static void createAndShowGUI() {
// Create and set up the window.
JFrame frame = new JFrame("FileChooserDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Add content to the window.
frame.add(new ProcessText());
// Display the window.
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
// Schedule a job for the event dispatch thread:
// creating and showing this application's GUI.
SwingUtilities.invokeLater(new Runnable() {
public void run() {
// Turn off metal's use of bold fonts
UIManager.put("swing.boldMetal", Boolean.FALSE);
createAndShowGUI();
}
});
}
}
TextStatistics.java
public class TextStatistics implements TextStatisticsInterface {
public Scanner fileScan;
public int[] countLetters = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // gives the starting values for count of each letter.
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; //initial amount of each letter. countLetters[0] corresponds to 'a'
//countLetters[1] to 'b' and so on.
public int[] length = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, //keeps word frequency lengths
0, 0, 0, 0, 0, 0, 0 };
int lineCount = 0; //keeps track of lines
int wordCount = 0; //keeps track of words
int charCount = 0; //keeps track of characters
double avg = 0;
double avgFinal = 0; //average word length
String strLine = "";
String largestWord;
File file;
ArrayList<Integer> line; //line with longest word length
/**
* reads in one file at a time and one line at a time to determine the
* statistics described above.
*
* @author Ryleigh More
*/
public TextStatistics(File file) {
Scanner scan;
try {
scan = new Scanner(file);
this.file = file;
line = new ArrayList<Integer>();
int largestIndex = 0;
while (scan.hasNextLine()) {
strLine = scan.nextLine().toLowerCase();
lineCount++;
charCount += strLine.length() + 1;
StringTokenizer tokenizer = new StringTokenizer(strLine,
" , .;:'\"&!?-_\n\t12345678910[]{}()@#$%^*/+-");
for (int i = 0; i < strLine.length(); i++) {
char theLetter = strLine.charAt(i);
if (theLetter >= 'a' && theLetter <= 'z')
countLetters[theLetter - 'a']++;
while (tokenizer.hasMoreTokens()) {
String theWord = tokenizer.nextToken();
int currentWordLength = theWord.length();
if (currentWordLength > largestIndex) {
largestWord = theWord;
largestIndex = currentWordLength;
line.clear();
}
if (largestWord.equals(theWord)) {
line.add(lineCount);
}
if (currentWordLength < 23 && currentWordLength > 0) {
length[currentWordLength]++;
}
wordCount++;
}
}
}
for (int j = 1; j < length.length; j++)
avg += (length[j] * j);
avgFinal = avg / wordCount;
scan.close();
} catch (FileNotFoundException e) {
System.out.println(file + " does not exist");
}
}
/**
* puts all the statistics in a String for printing by the ProcessText
* class.
*
* @return s
* @author Ryleigh Moore
*/
public String toString() {
DecimalFormat two = new DecimalFormat("#0.00");
String s = "Statistics for " + file + "\n"
+ "======================================================\n"
+ lineCount + " Lines\n" + wordCount + " Words\n" + charCount
+ " Characters\n" + "-----------------------------------------"
+ "\na= " + countLetters[0] + "\t n= " + countLetters[13]
+ "\nb= " + countLetters[1] + "\t o= " + countLetters[14]
+ "\nc= " + countLetters[2] + "\t p= " + countLetters[15]
+ "\nd= " + countLetters[3] + "\t q= " + countLetters[16]
+ "\ne= " + countLetters[4] + "\t r= " + countLetters[17]
+ "\nf= " + countLetters[5] + "\t s= " + countLetters[18]
+ "\ng= " + countLetters[6] + "\t t= " + countLetters[19]
+ "\nh= " + countLetters[7] + "\t u= " + countLetters[20]
+ "\ni= " + countLetters[8] + "\t v= " + countLetters[21]
+ "\nj= " + countLetters[9] + "\t w= " + countLetters[22]
+ "\nk= " + countLetters[10] + "\t x= " + countLetters[23]
+ "\nl= " + countLetters[11] + "\t y= " + countLetters[24]
+ "\nm= " + countLetters[12] + "\t z: " + countLetters[25]
+ "\n-----------------------------------------"
+ "\n Length Frequency" + "\n ------- ---------";
for (int q = 1; q < length.length; q++) {
if (length[q] > 0)
s += "\n\t" + q + " =\t" + length[q];
}
s += "\nThe average word length = " + two.format(avgFinal)
+ "\nThe longest word is '" + largestWord + "' and is on line "
+ line
+ "\n======================================================";
return s;
}
答案 0 :(得分：2)
public void actionPerformed(ActionEvent e) {
File file = null;
TextStatistics stat = null;
if (e.getSource() == openButton) {
int returnVal = fc.showOpenDialog(ProcessText.this);
if (returnVal == JFileChooser.APPROVE_OPTION) {
file = fc.getSelectedFile();
stat = new TextStatistics(file);
}
}
if (e.getSource() == calculate) {
log.append(stat.toString());
}
}
问题是，当您按下openButton时，它会创建新的TextStatisics，但就是。它不会将文本附加到JTextArea。你只有按calculate才能这样做。因此，当按下openButton时，会创建本地TextStatistics，然后没有任何内容与它一起，所以它被抛出。按下calculate时，日志会尝试附加空TextStatistics。
因此，您可以将TextStatistics stat附加到log 内的if (e.getSource() == openButton) { 或 make TextStatistics stats一个全局类成员，它将在按下按钮之间保持不变。因此，当按下openButton时，TextStatisitcs stat会一直按calculate按钮。
答案 1 :(得分：0)
每次运行actionPerformed时，它都会生成一个新变量stat并将其设置为null。但实际上，您希望对actionPerformed进行两次不同的调用，以使用相同的变量副本。
我建议在所有方法之前将声明TextStatistics stat = null;移出actionPerformed并将其放在类的顶部，以便stat成为类的一个字段。这样，它的值将从一个actionPerformed调用到下一个调用。