Question

I have a code that read file and store in arraylist and then convert to array(To use for table model)

My class extends abstracttablemodel correctly.

My All Code is:

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import javax.swing.table.AbstractTableModel;

public class ReadFileToList extends AbstractTableModel{
String[] col={"Fname","Lname","Number"};
List<String> data=new ArrayList<String>();
String[][] Arraydata;

public ReadFileToList(){
try{
FileReader fr=new FileReader("D:\\AllUserRecords.txt");
BufferedReader br=new BufferedReader(fr);
String line;
while((line=br.readLine()) !=null){
    data.add(line);
}
br.close();
Arraydata=(String[][]) data.toArray();
}
catch(IOException ioe){
    ioe.printStackTrace();
}
}

@Override
public String getColumnName(int colu){
return col[colu];
}

public int getRowCount() {
return Arraydata.length;
}

public int getColumnCount() {
return col.length;
}

public Object getValueAt(int rowIndex, int columnIndex) {
return Arraydata[rowIndex][columnIndex];
}
}

My main Class is ReadFileToListM:

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;

public class ReadFileToListM  {
ReadFileToList rftl=new ReadFileToList();
public ReadFileToListM(){
    JFrame frame=new JFrame();
    JTable table=new JTable(rftl);
    JPanel panel=new JPanel();
    JScrollPane sp=new JScrollPane(table);
    panel.add(sp);
    frame.add(panel);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(470,470);
    frame.setVisible(true);
}

public static void main(String[] args){
    new ReadFileToListM();
}
}

but it has Exception!

this is my Exceptions:

Exception in thread "main" java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [[Ljava.lang.String;
    at javaapplication1.ReadFileToList.<init>(ReadFileToList.java:37)
    at javaapplication1.ReadFileToListM.<init>(ReadFileToListM.java:8)
    at javaapplication1.ReadFileToListM.main(ReadFileToListM.java:22)
Java Result: 1

My txt File:

 FName Lname Number
 second secondsecond 22
 thired thithird 33
 fourth fourfourr 44
 fifth fiffif 55

Please help me, Thanks.

Answer 1

Contructor of the ReadFileToList class is empty, you should change:

public void readtolist() throws IOException{

to

public ReadFileToList() throws IOException{

because if dont do that initialization of your model(code below) doesnt execute your method which put data in your collections but only execute contructor from extended class.

ReadFileToList rftl=new ReadFileToList();

2nd

You can’t cast List which is one-dimential dynamic sized array to two-dimential array. Other methods from your model looks good.

Also you should somehow seperate data from the File. At this moment it’s only splitted to to rows.

It will be really helpful if you show us few lines from the file.

EDIT: 06-01-2013 After posting file content Change Countructor in model to this one

public ReadFileToList() throws IOException{
    FileReader fr=new FileReader("D:/AllUserRecords.txt"); //one slash instead of two backslash
    BufferedReader br=new BufferedReader(fr);
    String line = br.readLine();
    while((line=br.readLine()) !=null){
        data.add(line.trim());  //trim() delete spaces before and after line
        System.out.println(line);
    }
    br.close();
    Arraydata = new String[data.size()][];
    for (int i=0;i<data.size();i++){
        Arraydata[i]=data.get(i).split(" "); //split text to array by space
    }

}

main should look like this

public class ReadFileToListM  {

public ReadFileToListM() throws IOException{
    JFrame frame=new JFrame();
    ReadFileToList rftl=new ReadFileToList();
    JTable table=new JTable(rftl);
    JPanel panel=new JPanel();
    JScrollPane sp=new JScrollPane(table);
    panel.add(sp);
    frame.add(panel);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(470,470);
    frame.setVisible(true);
}

public static void main(String[] args) throws IOException{
    new ReadFileToListM();
}
}

Result: