无法从另一个类打印到JTextArea

Question

I am attempting to print to my JTextArea from another class. I have the class ActivityLogger call method Alert inside of my main class Risk_Mgnt_Manager which is where the JTextArea is located. I am able to pass the string into this method and print to counsel but it won't append or setText to the JTextArea. What am I missing?

My goal is to have different classes send messages to the class ActivityLogger which in turn sends it to the JTextArea.

Any examples are appreciated and Thank you in advance.

Main class

package risk_mgnt_manager;

import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;
import java.sql.SQLException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.xml.parsers.ParserConfigurationException;
import org.xml.sax.SAXException;

public class Risk_Mgnt_Manager extends JFrame{
    boolean begin = false;
    String message = null;
    JTextArea text = new JTextArea();
    JButton Start = new JButton("Start");//exit program button
    JButton End = new JButton("End");//Ok button executes message creation
    JButton Exit = new JButton("Exit Program");

public void Alert(String a){
    System.out.println(a); // This is printing correctly  
    text.append(a + "\n"); // why won't this display the string?
}

public Risk_Mgnt_Manager(){
    text.setEditable(false);
    text.setWrapStyleWord(true);
    text.setLineWrap(true);
    JScrollPane scroll = new JScrollPane(text);

    setLayout(new GridLayout(2, 3, 5, 5)); //LayoutManager Setup
    JPanel myPanel = new JPanel(new GridLayout(3,0));
    //JPanel myPanel2 = new JPanel(new GridLayout(1, 1));
    //JPanel myPanel3 = new JPanel(new GridLayout(1, 1));
    JPanel myPanel4 = new JPanel(new GridLayout(1, 1));

    myPanel.add(new JLabel("Start Automated Processes: "));
    myPanel.add(Start);

    myPanel.add(new JLabel("End Automated Processes: "));
    myPanel.add(End);

    myPanel.add(new JLabel("  "));
    myPanel.add(Exit);
    myPanel4.add(text);

    Start.addActionListener(new startActions());//Listener for button 1
    End.addActionListener(new stopActions());//Listener for button 2
    Exit.addActionListener(new Quit());//Listener for button 2

    add(myPanel);
    //add(myPanel2);
    //add(myPanel3);
    add(myPanel4);

}

public void StartAutomation(boolean start) throws SAXException,     ParserConfigurationException, IOException, SQLException{
        //calls test class
        Test t = new Test();
        t.mainTest(begin);

        //ignore these classes
        // Step one import settlement data from FIX 1 settlement tables
        ImportSettles tbl = new ImportSettles();
        //tbl.DataTransfer(begin);

        // Step two import Real-Time price data from t_span_price on FIX 1
        ImportSpanPrice tbl2 = new ImportSpanPrice();
        //tbl2.DataTransfer1(begin);

        // Step three import from xml file
        ImportTradeData tbl3 = new ImportTradeData();
        //tbl3.parseXML(begin);

        // Step four not used as of 11/26/2013
        ImportFirmRpt tbl4 = new ImportFirmRpt();

        // Step five import poew.csv file
        ImportPOEW tbl5 = new ImportPOEW();
        //tbl5.csvImportPOEW(begin);

        // Step six import paycollect.csv file
        ImportPaycollect tbl6 = new ImportPaycollect();
        //tbl6.csvImportPaycollect(begin);

        // Step seven import data from RISK 1
        ImportSecDeposit tbl7 = new ImportSecDeposit();
        //tbl7.DataTransfer2(begin);

        // Step 8 import FCM financial info, WinJammer not used as of 11/26/2013
        ImportFCM tbl8 = new ImportFCM();


        // Step nine import CGM_post.csv file
        ImportCGMPost tbl9 = new ImportCGMPost();
        //tbl9.csvImportCGMPost(begin);

        // Step ten import RM_Intraday_paycollect.csv
        ImportIntraday tbl10 = new ImportIntraday();
        //tbl10.csvImportIntra(begin);   
}

private static void ProjectFrame(){
    Risk_Mgnt_Manager projectFrame = new Risk_Mgnt_Manager();
    projectFrame.setSize(500, 300); //JFrame size set
    projectFrame.setLocationRelativeTo(null); //JFrame centered to center of screen
    projectFrame.setTitle("Automation Control"); //JFrame Title
    projectFrame.setVisible(true);//JFrame is visible upon start of program
    projectFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}



public static void main(String[] args) {
    ProjectFrame();
}
static class Quit implements ActionListener {
        public void actionPerformed (ActionEvent e) {
            //Once Exit JButton is pressed the program exits
            System.exit(0);
        }
    }
public class startActions implements ActionListener {
        public void actionPerformed (ActionEvent e) {
            //Once Exit JButton is pressed the program exits
            begin = true;
            try {
                StartAutomation(begin);
            } catch (SAXException ex) {
                Logger.getLogger(Risk_Mgnt_Manager.class.getName()).log(Level.SEVERE, null, ex);
            } catch (ParserConfigurationException ex) {
                Logger.getLogger(Risk_Mgnt_Manager.class.getName()).log(Level.SEVERE, null, ex);
            } catch (IOException ex) {
                Logger.getLogger(Risk_Mgnt_Manager.class.getName()).log(Level.SEVERE, null, ex);
            } catch (SQLException ex) {
                Logger.getLogger(Risk_Mgnt_Manager.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
    }
public class stopActions implements ActionListener {
        public void actionPerformed (ActionEvent e) {
            //Once Exit JButton is pressed the program exits
            begin = false;
            try {
                StartAutomation(begin);
            } catch (SAXException ex) {
                Logger.getLogger(Risk_Mgnt_Manager.class.getName()).log(Level.SEVERE, null, ex);
            } catch (ParserConfigurationException ex) {
                Logger.getLogger(Risk_Mgnt_Manager.class.getName()).log(Level.SEVERE, null, ex);
            } catch (IOException ex) {
                Logger.getLogger(Risk_Mgnt_Manager.class.getName()).log(Level.SEVERE, null, ex);
            } catch (SQLException ex) {
                Logger.getLogger(Risk_Mgnt_Manager.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
    } 
} 

Test class

package risk_mgnt_manager;

import java.util.Date;

/**
 *
 * @author bgilbert
 */
public class Test {
    public void mainTest(boolean a){
        ActivityLogger act = new ActivityLogger();
        act.logger("Testing message reporting " + new Date(), 1, true);
}

}

ActivityLogger class

package risk_mgnt_manager;
/**
 *
 * @author MLaMeyer
 */
public class ActivityLogger{
     private String message;

    // this will perform different purposes once I can print to JTextArea
    public void logger(String log, int type, boolean execution){
    if (execution == true) {

                message = log;
    } 
            if (execution == false) {

                message = log;
    } 

            print();

}
    // calls method Alert in main class and passes the string correctly
    public void print(){
      Risk_Mgnt_Manager m = new Risk_Mgnt_Manager();
      m.Alert(message);
    }
}

Answer 1

You need to update the UI in separate Thread , I mean UI related operations should run on the Event dispatch thread. Add constructor in your ActivityLogger class like Hovercraft's solution then try,

SwingUtilities.invokeLater(new Runnable() {
    public void run() {
      text.append(a+"\n");
    }
 });

Answer 2

Your program prints out to the other class, just not in the object displayed:

public void print(){
  Risk_Mgnt_Manager m = new Risk_Mgnt_Manager();
  m.Alert(message);
}

When you create a new Risk_Mgnt_Manager, you do just that, create a new completely unique Risk_Mgnt_Manager object, one that is not displayed. Printing to it will have no effect on the displayed one.

A the solution is to pass in a reference to your logger class to the actual displayed Risk_Mgnt_Manager object.

public class ActivityLogger{
     private String message;
     private Risk_Mgnt_Manager m; // ***** added

     public ActivityLogger(Risk_Mgnt_Manager m) {
       this.m = m; // ****** added
     }

    // this will perform different purposes once I can print to JTextArea
    public void logger(String log, int type, boolean execution){
    if (execution == true) {

                message = log;
    } 
            if (execution == false) {

                message = log;
    } 

            print();

}
    // calls method Alert in main class and passes the string correctly
    public void print(){
      // Risk_Mgnt_Manager m = new Risk_Mgnt_Manager();
      SwingUtilities.invokeLater(new Runnable() {
        public void run() {
          m.Alert(message);
        }
      });
    }
}

Whatever you do, don't attempt to solve this my making anything static as that road will lead to misery.

Answer 3

First of all make the frame visible in your constructor .

public Risk_Mgnt_Manager(){

setVisible(true);

}

Then as per solution by Hovercraft pass by reference.