问题
I am messing around with java swing and am trying to open a text file containing existing data with a JTextArea. It doesn't seem to be saving any changes regardless of the different things I have tried.
Below is code that reads the text file fine, but doesn't write it (obviously).
If someone could please advise me as to how I could successfully save changes to the JTextArea I would be greatful.
package funwithswing;
import java.awt.*;
import javax.swing.*;
import java.io.*;
import java.util.Scanner;
import javax.swing.border.EmptyBorder;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class AllDataGUI extends JFrame{
public AllDataGUI(){
fileRead();
panels();
}
private String storeAllString="";
private JButton saveCloseBtn = new JButton("Save Changes and Close");
private JButton closeButton = new JButton("Exit Without Saving");
private JFrame frame=new JFrame("Viewing All Program Details");
private JTextArea textArea = new JTextArea(storeAllString,0,70);
private JButton getCloseButton(){
return closeButton;
}
private void fileRead(){
try{
FileReader read = new FileReader("CompleteData.txt");
Scanner scan = new Scanner(read);
while(scan.hasNextLine()){
String temp=scan.nextLine()+"\n";
storeAllString=storeAllString+temp;
}
}
catch (Exception exception)
{
exception.printStackTrace();
}
}
private void fileWrite(){
try{
FileWriter write = new FileWriter ("CompleteData.txt");
textArea.write(write);
}
catch (Exception e){
e.printStackTrace();
}
}
private void panels(){
JPanel panel = new JPanel(new GridLayout(1,1));
panel.setBorder(new EmptyBorder(5, 5, 5, 5));
JPanel rightPanel = new JPanel(new GridLayout(15,0,10,10));
rightPanel.setBorder(new EmptyBorder(15, 5, 5, 10));
JTextArea textArea = new JTextArea(storeAllString,0,70);
JScrollPane scrollBarForTextArea=new JScrollPane(textArea,JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
panel.add(scrollBarForTextArea);
frame.add(panel);
frame.getContentPane().add(rightPanel,BorderLayout.EAST);
rightPanel.add(saveCloseBtn);
rightPanel.add(closeButton);
closeButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
frame.dispose();
}
});
frame.setSize(1000, 700);
frame.setVisible(true);
frame.setLocationRelativeTo(null);
}
private void saveBtn(){
}
}
回答1:
There are some mistakes in your code, I have modified those. Compile and run the below code This will solv your problem.
import java.awt.*;
import javax.swing.*;
import java.io.*;
import java.util.Scanner;
import javax.swing.border.EmptyBorder;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class AllDataGUI extends JFrame{
public AllDataGUI(){
fileRead();
panels();
}
private String storeAllString="";
private JButton saveCloseBtn = new JButton("Save Changes and Close");
private JButton closeButton = new JButton("Exit Without Saving");
private JFrame frame=new JFrame("Viewing All Program Details");
// private JTextArea textArea = new JTextArea(storeAllString,0,70);
private JTextArea textArea = new JTextArea();
private JButton getCloseButton(){
return closeButton;
}
private void fileRead(){
try{
FileReader read = new FileReader("CompleteData.txt");
Scanner scan = new Scanner(read);
while(scan.hasNextLine()){
String temp=scan.nextLine()+"\n";
storeAllString=storeAllString+temp;
}
textArea.setText(storeAllString);
}
catch (Exception exception)
{
exception.printStackTrace();
}
}
private void panels(){
JPanel panel = new JPanel(new GridLayout(1,1));
panel.setBorder(new EmptyBorder(5, 5, 5, 5));
JPanel rightPanel = new JPanel(new GridLayout(15,0,10,10));
rightPanel.setBorder(new EmptyBorder(15, 5, 5, 10));
// JTextArea textArea = new JTextArea(storeAllString,0,70);
JScrollPane scrollBarForTextArea=new JScrollPane(textArea,JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
panel.add(scrollBarForTextArea);
frame.add(panel);
frame.getContentPane().add(rightPanel,BorderLayout.EAST);
rightPanel.add(saveCloseBtn);
rightPanel.add(closeButton);
closeButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
frame.dispose();
}
});
saveCloseBtn.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
saveBtn();
frame.dispose();
}
});
frame.setSize(1000, 700);
frame.setVisible(true);
frame.setLocationRelativeTo(null);
}
private void saveBtn(){
File file = null;
FileWriter out=null;
try {
file = new File("CompleteData.txt");
out = new FileWriter(file);
out.write(textArea.getText());
out.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] arg)
{
new AllDataGUI();
}
}
回答2:
You need to close FileWriter. Use try-with-resource of Java-7 or finally block to close resource properly.
private void fileWrite(){
FileWriter write=null;
try{
write = new FileWriter ("CompleteData.txt");
textArea.write(write);
}
catch (Exception e){
e.printStackTrace();
}
finally{
if(write != null)
write.close();
}
}
来源：https://stackoverflow.com/questions/24076612/opening-editing-and-saving-text-in-jtextarea-to-txt-file