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A Polite Boy
jTable data problem
0 Answer(s)      a year and 7 months ago
Posted in : Java Beginners


Hello. 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 void readtolist() throws IOException{
    FileReader fr=new FileReader("D:\\AllUserRecords.txt");
    BufferedReader br=new BufferedReader(fr);
    String line;
    while((line=br.readLine()) !=null){
        data.add(line);
        System.out.println(line);
    }
    br.close();
    Arraydata=(String[][]) data.toArray();
}

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! Please help me, Thanks.

this is my Exceptions:

Exception in thread "main" java.lang.NullPointerException
    at Library.ReadFileToList.getRowCount(ReadFileToList.java:30)
    at javax.swing.JTable.getRowCount(JTable.java:2583)
    at javax.swing.plaf.basic.BasicTableUI.createTableSize(BasicTableUI.java:1646)
    at javax.swing.plaf.basic.BasicTableUI.getPreferredSize(BasicTableUI.java:1687)
    at javax.swing.JComponent.getPreferredSize(JComponent.java:1632)
    at javax.swing.JViewport.getViewSize(JViewport.java:1018)
    at javax.swing.ScrollPaneLayout.preferredLayoutSize(ScrollPaneLayout.java:476)
    at java.awt.Container.preferredSize(Container.java:1616)
    at java.awt.Container.getPreferredSize(Container.java:1601)
    at javax.swing.JComponent.getPreferredSize(JComponent.java:1634)
    at java.awt.FlowLayout.layoutContainer(FlowLayout.java:594)
    at java.awt.Container.layout(Container.java:1432)
    at java.awt.Container.doLayout(Container.java:1421)
    at java.awt.Container.validateTree(Container.java:1519)
    at java.awt.Container.validateTree(Container.java:1526)
    at java.awt.Container.validateTree(Container.java:1526)
    at java.awt.Container.validateTree(Container.java:1526)
    at java.awt.Container.validateTree(Container.java:1526)
    at java.awt.Container.validate(Container.java:1491)
    at java.awt.Window.show(Window.java:820)
    at java.awt.Component.show(Component.java:1419)
    at java.awt.Component.setVisible(Component.java:1372)
    at java.awt.Window.setVisible(Window.java:801)
    at Library.ReadFileToListM.<init>(ReadFileToListM.java:20)
    at Library.ReadFileToListM.main(ReadFileToListM.java:24)
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at Library.ReadFileToList.getRowCount(ReadFileToList.java:30)
    at javax.swing.JTable.getRowCount(JTable.java:2583)
    at javax.swing.plaf.basic.BasicTableUI.createTableSize(BasicTableUI.java:1646)
    at javax.swing.plaf.basic.BasicTableUI.getPreferredSize(BasicTableUI.java:1687)
    at javax.swing.JComponent.getPreferredSize(JComponent.java:1632)
    at javax.swing.JViewport.getViewSize(JViewport.java:1018)
    at javax.swing.ScrollPaneLayout.preferredLayoutSize(ScrollPaneLayout.java:476)
    at java.awt.Container.preferredSize(Container.java:1616)
    at java.awt.Container.getPreferredSize(Container.java:1601)
    at javax.swing.JComponent.getPreferredSize(JComponent.java:1634)
    at java.awt.FlowLayout.layoutContainer(FlowLayout.java:594)
    at java.awt.Container.layout(Container.java:1432)
    at java.awt.Container.doLayout(Container.java:1421)
    at java.awt.Container.validateTree(Container.java:1519)
    at java.awt.Container.validateTree(Container.java:1526)
    at java.awt.Container.validateTree(Container.java:1526)
    at java.awt.Container.validateTree(Container.java:1526)
    at java.awt.Container.validateTree(Container.java:1526)
    at java.awt.Container.validate(Container.java:1491)
    at java.awt.Window.dispatchEventImpl(Window.java:2427)
    at java.awt.Component.dispatchEvent(Component.java:4240)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)
 BUILD STOPPED (total time: 4 seconds)

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 void readtolist() throws IOException{ FileReader fr=new FileReader("D:\AllUserRecords.txt"); BufferedReader br=new BufferedReader(fr); String line; while((line=br.readLine()) !=null){ data.add(line); System.out.println(line); } br.close(); Arraydata=(String[][]) data.toArray(); }

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.EXITONCLOSE); frame.setSize(470,470); frame.setVisible(true); }

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

but it has Exception! Please help me, Thanks.

this is my Exceptions:

Exception in thread "main" java.lang.NullPointerException at Library.ReadFileToList.getRowCount(ReadFileToList.java:30) at javax.swing.JTable.getRowCount(JTable.java:2583) at javax.swing.plaf.basic.BasicTableUI.createTableSize(BasicTableUI.java:1646) at javax.swing.plaf.basic.BasicTableUI.getPreferredSize(BasicTableUI.java:1687) at javax.swing.JComponent.getPreferredSize(JComponent.java:1632) at javax.swing.JViewport.getViewSize(JViewport.java:1018) at javax.swing.ScrollPaneLayout.preferredLayoutSize(ScrollPaneLayout.java:476) at java.awt.Container.preferredSize(Container.java:1616) at java.awt.Container.getPreferredSize(Container.java:1601) at javax.swing.JComponent.getPreferredSize(JComponent.java:1634) at java.awt.FlowLayout.layoutContainer(FlowLayout.java:594) at java.awt.Container.layout(Container.java:1432) at java.awt.Container.doLayout(Container.java:1421) at java.awt.Container.validateTree(Container.java:1519) at java.awt.Container.validateTree(Container.java:1526) at java.awt.Container.validateTree(Container.java:1526) at java.awt.Container.validateTree(Container.java:1526) at java.awt.Container.validateTree(Container.java:1526) at java.awt.Container.validate(Container.java:1491) at java.awt.Window.show(Window.java:820) at java.awt.Component.show(Component.java:1419) at java.awt.Component.setVisible(Component.java:1372) at java.awt.Window.setVisible(Window.java:801) at Library.ReadFileToListM.(ReadFileToListM.java:20) at Library.ReadFileToListM.main(ReadFileToListM.java:24) Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at Library.ReadFileToList.getRowCount(ReadFileToList.java:30) at javax.swing.JTable.getRowCount(JTable.java:2583) at javax.swing.plaf.basic.BasicTableUI.createTableSize(BasicTableUI.java:1646) at javax.swing.plaf.basic.BasicTableUI.getPreferredSize(BasicTableUI.java:1687) at javax.swing.JComponent.getPreferredSize(JComponent.java:1632) at javax.swing.JViewport.getViewSize(JViewport.java:1018) at javax.swing.ScrollPaneLayout.preferredLayoutSize(ScrollPaneLayout.java:476) at java.awt.Container.preferredSize(Container.java:1616) at java.awt.Container.getPreferredSize(Container.java:1601) at javax.swing.JComponent.getPreferredSize(JComponent.java:1634) at java.awt.FlowLayout.layoutContainer(FlowLayout.java:594) at java.awt.Container.layout(Container.java:1432) at java.awt.Container.doLayout(Container.java:1421) at java.awt.Container.validateTree(Container.java:1519) at java.awt.Container.validateTree(Container.java:1526) at java.awt.Container.validateTree(Container.java:1526) at java.awt.Container.validateTree(Container.java:1526) at java.awt.Container.validateTree(Container.java:1526) at java.awt.Container.validate(Container.java:1491) at java.awt.Window.dispatchEventImpl(Window.java:2427) at java.awt.Component.dispatchEvent(Component.java:4240) at java.awt.EventQueue.dispatchEvent(EventQueue.java:599) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160) at java.awt.EventDispatchThread.run(EventDispatchThread.java:121) BUILD STOPPED (total time: 4 seconds)

My txt File:

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

Thanks for help!


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