How to change the text in JTextField Dynamically

Question

i am trying to change the contents of JTextField dynamically like this
textfield.setText();but it is giving error...........how can i do it....

Answer 1

here is the code .....it is showing error in line 18 and 20 as identifier expected
their i am trying to make JTextField editable....
plz have a look
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import javax.swing.*;
import javax.swing.filechooser.*;
import javax.swing.SwingUtilities.*;
import javax.swing.filechooser.FileFilter;
//import javax.swing.JEditorPane;
import java.net.URL;
public class tm extends JFrame implements ActionListener
public JTextField[] programtext = new JTextField[30];
public JTextField[] tapetext = new JTextField[30];
tapetext.setEditable(true);
public JTextField[] statetext = new JTextField[30];
statetext.setEditable(true);
int count =0;
public static void main (String arg[]){
tm m=new tm();
m.setSize(1000,500);
m.show();
JButton loadp, run, step,loadi,loads;
public tm()
Container c ;
c = getContentPane();
c.setLayout(new FlowLayout());
loadi = new JButton("LOAD INPUT STRING");
c.add(loadi);
loadi.addActionListener(this);
loadi.setBounds(200,25,100,50);
loadp = new JButton("LOAD PROGRAM");
c.add(loadp);
loadp.addActionListener(this);
loadp.setBounds(300,25,100,50);
run = new JButton("RUN");
c.add(run);
run.addActionListener (this);
run.setBounds(400,25,100,50);
step = new JButton("STEP");
c.add(step);
step.addActionListener(this);
step.setBounds(500,25,100,50);
loads = new JButton("LOAD STATES");
c.add(loads);
loads.addActionListener(this);
loads.setBounds(600,25,100,50);
JPanel prog = new JPanel();
prog.setLayout(new GridLayout(30,1));
for(int i=0;i<programtext.length;i++)
programtext= new JTextField(10);
prog.add(programtext[i]);
JPanel tape = new JPanel();
tape.setLayout(new GridLayout(30,1));
for(int i=0;i<tapetext.length;i++)
tapetext[i]= new JTextField(10);
tape.add(tapetext[i]);
JPanel state = new JPanel();
state.setLayout(new GridLayout(30,1));
for(int i=0;i<statetext.length;i++)
statetext[i]= new JTextField(10);
state.add(statetext[i]);
JPanel contentPane3 = new JPanel();
contentPane3.setBorder(BorderFactory.createEmptyBorder(50, 50, 50, 50));
contentPane3.setLayout(new BorderLayout());
contentPane3.add(state, BorderLayout.CENTER);
contentPane3.add(c, BorderLayout.NORTH);
contentPane3.add(prog, BorderLayout.WEST);
contentPane3.add(tape, BorderLayout.EAST);
setContentPane(contentPane3);
public void actionPerformed(ActionEvent e)
try{
if(e.getSource ()==loadp)
JFileChooser chooser=new JFileChooser();
int r= chooser.showOpenDialog(this);
if(r==JFileChooser.APPROVE_OPTION )
String name=chooser.getSelectedFile().getName();
File f=chooser.getSelectedFile();
FileInputStream filestream = new FileInputStream(f);
BufferedInputStream bufferstream = new BufferedInputStream(filestream);
DataInputStream datastream = new DataInputStream(bufferstream);
String record = null;
programtext[0].setText("");
try { 
int i = 0;
while (true)
record=datastream.readLine();
if(record == null){
break;
programtext[i].setText(record);
i++;
count = count + 1;
System.out.println ("the no of lines of the program are"+ count);
catch (Exception p)
System.out.println(p);
else if(e.getSource()==loads)
JFileChooser chooser3=new JFileChooser();
int r3= chooser3.showOpenDialog(this);
if(r3==JFileChooser.APPROVE_OPTION)
String name=chooser3.getSelectedFile ().getName();
File f3=chooser3.getSelectedFile();
FileInputStream filestream3 = new FileInputStream(f3);
BufferedInputStream bufferstream3 = new BufferedInputStream(filestream3);
DataInputStream datastream3 = new DataInputStream(bufferstream3);
String record3 = null;
statetext[0].setText("");
try { 
int i = 0;
while (true)
record3=datastream3.readLine();
if(record3 == null){
break;
statetext[i].setText(record3);
i++;
catch (Exception p3)
System.out.println(p3);
else if(e.getSource()==loadi)
JFileChooser chooser2=new JFileChooser();
int r2= chooser2.showOpenDialog(this);
if(r2==JFileChooser.APPROVE_OPTION )
String name=chooser2.getSelectedFile().getName();
File f2=chooser2.getSelectedFile();
FileInputStream filestream2 = new FileInputStream(f2);
BufferedInputStream bufferstream2 = new BufferedInputStream(filestream2);
DataInputStream datastream2 = new DataInputStream(bufferstream2);
String record2 = null;
tapetext[0].setText("");
try { 
int i = 0;
while (true)
record2=datastream2.readLine();
if(record2 == null){
break;
tapetext[i].setText(record2);
i++;
catch (Exception p2)
System.out.println(p2);
else if(e.getSource ()==run)
String temp="";
String statetemp=" ";
String tapetemp=" ";
int l=0;
int tp=0;
String pars[][] = new String[50][5];
     for(int m=0;m<count;m++){
temp = programtext[m].getText();
String str[]=temp.split(" ");
for(int k=0;k<5;k++){
pars[m][k] =str[k];
System.out.println(pars[m][k]);
statetemp = statetext[0].getText();
tapetemp = tapetext[l].getText();
while(pars[tp][0]==statetemp && pars[tp][1]==tapetemp && tp><count)
     statetemp = pars[tp][2];
     tapetemp = pars[tp][3];
     statetext[0].setText() = statetemp;
     tapetext[tp].setText() = tapetemp;
     if(pars[tp][4]=="R")
     l=l+1;
     else{
     l=l-1;
     tp++;      
else if(e.getSource()==step)
catch(Exception t)
System.out.println(t);