Hi Friend,

Try the following code:

import java.io.*;
import java.util.*;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;

class ShowData implements Comparable{
int id;
String name;
int marks;
String grade;
public void setId(int id){
this.id=id;
}
public int getId(){
return id;
}
public void setName(String name){
this.name=name;
}
public String getName(){
return name;
}
public void setMarks(int marks){
this.marks=marks;
}
public int getMarks(){
return marks;
}
public void setGrade(String grade){
this.grade=grade;
}
public String getGrade(){
return grade;
}
public int compareTo(Object Student) throws ClassCastException {
if (!(Student instanceof ShowData))
throw new ClassCastException("Error");
int ide = ((ShowData) Student).getId();
return this.id - ide;
}
}
public class SortFileData{
SortFileData(){
JFrame f=new JFrame();
JPanel p=new JPanel();
JButton b=new JButton("View");
final JTextArea area=new JTextArea(10,50);
JScrollPane pane=new JScrollPane(area);

p.add(area);
p.add(b);
f.add(p);
f.setVisible(true);
f.pack();

b.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae){
int j=0;
ShowData data[]=new ShowData[5];
try{
FileInputStream fstream = new FileInputStream("C:\\school.txt");
DataInputStream in = new DataInputStream(fstream);
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String strLine;
ArrayList list=new ArrayList();
while ((strLine = br.readLine()) != null){
list.add(strLine);
}
Iterator itr;
for (itr=list.iterator(); itr.hasNext(); ){
String str=itr.next().toString();
String [] splitSt =str.split(" ");
String id="",name="",marks="",grade="";
for (int i = 0 ; i < splitSt.length ; i++) {
id=splitSt[0];
name=splitSt[1];
marks=splitSt[2];
grade=splitSt[3];

}
data[j] = new ShowData();
data[j].setId(Integer.parseInt(id));
data[j].setName(name);
data[j].setMarks(Integer.parseInt(marks));
data[j].setGrade(grade);
j++;
}
}
catch(Exception e){}
Arrays.sort(data);
System.out.println("********Sorted by id********");
String strVal="";
for (int i=0; i<5; i++) {
ShowData show = data[i];
int no=show.getId();
String name = show.getName();
int marks = show.getMarks();
String grade = show.getGrade();
System.out.println(no + " " + name + " " + marks+" " +grade);
String d= no + " " + name + " " + marks+" " +grade;
ArrayList al = new ArrayList();
al.add(d+"\n");

Iterator itr = al.iterator();
while(itr.hasNext())
{
strVal+= itr.next().toString()+" ";
}
}
area.setText(strVal);
}
});
}
public static void main(String[]args){
SortFileData data=new SortFileData();

}
}
Thanks

For the above code, we have used following file data:

school.txt

4 A 87 A
5 B 99 A+
1 C 75 A
2 D 55 C
3 E 68 B

Thanks