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Accessing parent class object through thread

开发者 https://www.devze.com 2023-03-21 17:37 出处:网络
My question is, In my code I have made a JTable in main class. Now I am making a thread To do some task and to collect some data which i want to fill in the JTable as soon as the thread collects it. T

My question is, In my code I have made a JTable in main class. Now I am making a thread To do some task and to collect some data which i want to fill in the JTable as soon as the thread collects it. This thread should run for a while. So Can I access the JTable of main class through the Thread created.

EDIT: I'm providing my code here.

Test.java

package test;


import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.AbstractTableModel;
import java.awt.*;

public class Test implements ActionListener {

 Thread t;
 JTable table;
 JScrollPane scrollPane;
 JButton b;
 JFrame frame;


 public void body() {

  frame = new JFrame("TableDemo");
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  frame.setLayout(new FlowLayout());

  table = new JTable(new MyTableModel());
  table.setPreferredScrollableViewportSize(new Dimension(500, 70));
  table.setFillsViewportHeight(true);

  scrollPane = new JScrollPane(table);
  frame.add(scrollPane);

  b = new JButton("OK");
  frame.add(b);

  thread a = new thread(new MyTableModel());
  t = new Thread(a);

  frame.pack();
  frame.setVisible(true);

  b.addActionListener(this);

 }


 public static void main(String[] args) {

  new Test().body();

 }


 @Override
 public void actionPerformed(ActionEvent e) {

  t.start();

 }
}


class MyTableModel extends AbstractTableModel {

 private String[] columnNames = {
  "First Name",
  "开发者_开发技巧Last Name",
  "Sport"
 };

 private Object[][] data = {
  {
   "a",
   "a",
   "a"
  }
 };

 @Override
 public int getColumnCount() {
  return columnNames.length;
 }

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

 public String getColumnName(int col) {
  return columnNames[col];
 }

 public Object getValueAt(int row, int col) {
  return data[row][col];
 }
 public Class getColumnClass(int c) {
  return getValueAt(0, c).getClass();
 }
 public boolean isCellEditable(int row, int col) {
  if (col < 3) {
   return false;
  } else {
   return true;
  }
 }
 public void setValueAt(Object value, int row, int col) {
  data[row][col] = value;
  fireTableCellUpdated(row, col);
 }

}

thread.java

package test;

public class thread implements Runnable {

  MyTableModel model;

    thread(MyTableModel model){
        this.model = model;
    }

    @Override
    public void run() {
        Object aa = "new value";
        this.model.setValueAt(aa, 0, 0);
        System.out.println(this.model.getValueAt(0, 0));
    }       

}

What I actually want is The value at 0,0 on the display screen of the JTable should Change from "a" to "new value".

Please give some help.


When you create a thread you actually create a Runnable class, either by extending Thread or implementing Runnable. So you will have your own class such as this

 MyClass implements Runnable {
     public void run() { ... your work here ... }
 }

Simply pass any objects you like to the constructor of this class

 MyClass implements Runnable {


     JTable m_jtable;

     public MyClass( JTable theTable ) { m_jtable = theTable; }

     public void run() { do things with m_jtable }
 }


It's been a while I've been doing Swing programming, but you probably want to have your Thread updating table's model instead of messing with JTable itself. In any case it will have a model, whether you create it or not.

So you should have the Thread that is collecting the data have a reference to the model, and once collection is done, fire some events in order to have the table updated (for instance http://download.oracle.com/javase/7/docs/api/javax/swing/table/AbstractTableModel.html#fireTableDataChanged()).

You should avoid littering your code with public references to internals of your application, i.e. do not have your table/model available as a public variable somewhere. Know where your objects live, it keep things tidy.

EDIT:

So you would have your model:

public class MyModel extends AbstractTableModel {
    private ClassDescribingYourData data;

    public void update(ClassDescribingYourData data) {
        this.data = data;
        fireTableDataChanged();
    }
}

And your data collector:

public class DataCollector implements Runnable {
    private final MyModel model;

    public DataCollector(MyModel model) {
        this.model = model;
    }

    public void run() {
        //1. collect data
        collectedData = ..
        //2. update model
        this.model.update(collectedData);
    }
 }

Then, you'd either use some Executor or simply do:

 DataCollector collector = new DataCollector(referenceToYourModel);
 new Thread(collector).start();

Above is not a complete implementation but I hope it explains the idea.

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