Passing values between two JPanel forms in Java Swing.

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I have created 3 classes. 1st class is used to store variable. other classes are use to input data and to display data.

1st Class

Java

public class Student {

    /**
     * @param args the command line arguments
     */
    
    private String strStudNo;
    private String strStudName;
    private int iMaths;
    private int iScience;
    private int iEnglish;

    public String getStrStudNo() {
        return strStudNo;
    }

    public void setStrStudNo(String strStudNo) {
        this.strStudNo = strStudNo;
    }

    public String getStrStudName() {
        return strStudName;
    }

    public void setStrStudName(String strStudName) {
        this.strStudName = strStudName;
    }

    public int getiMaths() {
        return iMaths;
    }

    public void setiMaths(int iMaths) {
        this.iMaths = iMaths;
    }

    public int getiScience() {
        return iScience;
    }

    public void setiScience(int iScience) {
        this.iScience = iScience;
    }

    public int getiEnglish() {
        return iEnglish;
    }

    public void setiEnglish(int iEnglish) {
        this.iEnglish = iEnglish;
    }
    
    public double  calTotal(){
        return (getiMaths()+getiScience()+getiEnglish());   
    }
    
    public double  calAverage(){
        
        return (calTotal()/3);  
    }
    
    public String findGrade(){
        
        String strGrade = new String();
        
        if (calAverage()>70){
            
            strGrade = "A";
            
        }else if(calAverage()>60){
            
            strGrade = "B";
            
        }else if (calAverage()>50){
            
            strGrade = "S";
            
        }else{
            strGrade = "Fail";
        }
        return strGrade;
    }
    
    public static void main(String[] args) {
        // TODO code application logic here
    }
}

2nd Class

This is class is designed using the Swing JPanel object and used to enter StudNo, StudName, Marks for 3 subjects. This also include 2 buttons as btnCalculate and btnCancel. This user interface was developed using Java swing class by auto generating. When the btnCalculate clicks the data within the textfields will be assign to the 1st classes variables. And at there the calculations will be done using 3 methods.

Java

 import javax.swing.JFrame;

/**
 *
 * @author Administrator
 */
@SuppressWarnings("serial")
public class EnterDetails extends javax.swing.JPanel {

    /**
     * Creates new form EnterDetails
     */
    
    public static void main(String[] args) {
        
        JFrame oJFrame = new JFrame();
        oJFrame.getContentPane().add(new EnterDetails());
        oJFrame.setDefaultCloseOperation(oJFrame.EXIT_ON_CLOSE);
        oJFrame.setSize(500, 500);
        oJFrame.setVisible(true);
        
    }
    public EnterDetails() {
        initComponents();
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
                    

    private void btnCalculateActionPerformed(java.awt.event.ActionEvent evt) {                                             
        // TODO add your handling code here:
        
        JPanelOnJFrameMulti oJpanelOnJFrameMulti = new JPanelOnJFrameMulti();
        
        oJpanelOnJFrameMulti.setStrStudNo(txtStudId.getText());
        oJpanelOnJFrameMulti.setStrStudName(txtStudName.getText());
        
        oJpanelOnJFrameMulti.setiMaths(Integer.parseInt(txtMaths.getText()));
        oJpanelOnJFrameMulti.setiScience(Integer.parseInt(txtScience.getText()));
        oJpanelOnJFrameMulti.setiEnglish(Integer.parseInt(txtEnglish.getText()));
        
        oJpanelOnJFrameMulti.calTotal();
        oJpanelOnJFrameMulti.calAverage();
        oJpanelOnJFrameMulti.findGrade(); 
       
        DisplayDetails oDisplayDet = new DisplayDetails();
        
        oDisplayDet.setVisible(true);
        
        
        JFrame oJFDisDet = new JFrame();
       
      
        oJFDisDet.getContentPane().add(new DisplayDetails());
        oJFDisDet.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        oJFDisDet.setSize(500, 500);
        oJFDisDet.setVisible(true);    
        
    }                                            

    // Variables declaration - do not modify                     
    private javax.swing.JButton btnCalculate;
    private javax.swing.JButton btnCancel;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JLabel jLabel4;
    private javax.swing.JLabel jLabel5;
    private javax.swing.JTextField txtEnglish;
    private javax.swing.JTextField txtMaths;
    private javax.swing.JTextField txtScience;
    private javax.swing.JTextField txtStudId;
    private javax.swing.JTextField txtStudName;
    // End of variables declaration                   
}

3rd Class

The other user interface that used to view the final results of the calculations i.e. Total marks, Average marks and the grade. When the btnCalculate clicks the result should pass to the 3rd class i.e. DisplayInfo JPanel class. My Problem is when I click the btnCalculate button it does calculate the total marks, average marks and the grade. The 3rd class i.e. the DisplayInfo JPanel form will also displayed but the data did not pass the text fields were empty.

I do not know what I have done wrong? Please can someone help me.

Update

Java

public class DisplayDetails extends JPanel {

    /**
     * Creates new form DisplayDetails
     */
    
    
    public void load(){
        
      Student oStudent = new Student();
      txtStudId.setText(oStudent.getStrStudName());
      txtStudId.setText(oStudent.getStrStudNo());
      
      txtTotal.setText(Double.toString(oStudent.calTotal()));
      txtAverage.setText(Double.toString(oStudent.calAverage()));
      
      txtGrade.setText(oStudent.findGrade()); 
        
    }
   
    public DisplayDetails() {
        initComponents();
    }
    
   // DisplayDetails.

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          

    }// </editor-fold>                        
    // Variables declaration - do not modify                     
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JLabel jLabel4;
    private javax.swing.JLabel jLabel5;
    private javax.swing.JTextField txtAverage;
    private javax.swing.JTextField txtGrade;
    private javax.swing.JTextField txtStudId;
    private javax.swing.JTextField txtStudName;
    private javax.swing.JTextField txtTotal;
    // End of variables declaration                   
}

THank You
Chiranthaka.

Posted 2-Jul-13 22:55pm

Chiranthaka Sampath

Updated 6-Dec-17 13:58pm

v3

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3 solutions

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TorstenH. · Accepted Answer · 2013-07-02T23:57:00

Solution 1

Do not place your data in the JPanel:

Java

public static void main(String[] args) {

        MyData oData = new MyData();// create data object

        JFrame oJFrame = new JFrame(); 
        oJFrame.getContentPane().add(new EnterDetails(oData));// pass Object to GUI Component as an argument
        oJFrame.setDefaultCloseOperation(oJFrame.EXIT_ON_CLOSE);
        oJFrame.setSize(500, 500);
        oJFrame.setVisible(true);
        
    }

and please rip that main-function out of the JPanel. the main function belongs into a seperate class:

Java

public class Application{
      public static void main(String[] args) {

        // create data object
        MyData oData = new MyData();

        JFrame oJFrame = new JFrame(); 
        oJFrame.getContentPane().add(new EnterDetails(oData));// pass Object to GUI Component as an argument
        oJFrame.setDefaultCloseOperation(oJFrame.EXIT_ON_CLOSE);
        oJFrame.setSize(500, 500);
        oJFrame.setVisible(true);
        
    }
}

That class "Application" defines your application's lifecycle.
The GUI components are only for visual representation. You can create, change and destroy them whenever you need to.

Posted 2-Jul-13 23:57pm

TorstenH.

Comments

Chiranthaka Sampath 3-Jul-13 6:01am

Ok pal then what does MyData class do? Is it similar to the "public class JPanelOnJFrameMulti{}" in my program that stores values?

TorstenH. 3-Jul-13 7:07am

Yes, please split the class and seperate GUI and data. That is a common design in applications, here in a light version, sometimes (*) in an enhanced version and in big frameworks in a heavy version.

(*) Java SE Application Design With MVC

Chiranthaka Sampath 3-Jul-13 7:18am

My GUIs are in separate classes and the variables are in a separate class. I cannot understand what you are telling me sir!

Chiranthaka Sampath 3-Jul-13 7:34am

Ok sir I have deleted the main() from the JPanel Forms. Then I have executed the 1st class and it was a sucess. But as the previous attempts the results from the 1st class i.e. calTotal(),calAverage() and the findGrade() will return any answers but the 2nd GUIs doesn't seem to grab that results from the 1st class i.e. the variables and the other calculations are reside. I can't find the problem please help me.

TorstenH. 3-Jul-13 7:46am

You need to have more than one student - and then to setz the values to the student object via the set methods.

Please be aware that you have to much main-methods in there. only one main method should be used. it#s the entry point for the machine to execute the code - it would cause confusion if the code can be accessed from different locations.

Chiranthaka Sampath 4-Jul-13 2:33am

Ok I have deleted all unnecessary main ( ) from the 2 JPanel classes to avoid confusions over accessing the classes. But now my problem is when I enter values from the 1st JPanel form I want the calculation done at the Student { } class and retrieve that data from the 2nd JPanel form. When the Calculate button on the JPanel Form 1 clicked the 2nd Jpanel forms loaded perfectly. But the data I have passed from the student class to the 2nd JPanel does not display. My source code for the second JPanel form is in the Updated question.

TorstenH. 4-Jul-13 3:02am

looks quite good on a short review. I assume there are other parts that lay out the components - not visible here.
You might need to update the GUI after adding the data by calling the Jpanel's update() method.

Chiranthaka Sampath 4-Jul-13 3:41am

I can't find any Update ( ) method regarding the JPanel form.

Chiranthaka Sampath 4-Jul-13 4:07am

All I want is when the 2nd JPanel form i.e. DisplayDetails opens the data in the Student class to be inserted to the TextFields of the DisplayDetails form. I am stuck at that point. If you please give me some clue about that. Because Ypu have mentioned about the JPanel's update ( ) but I couldn't find that. I don't think that is an inbuilt one. Thank You!

TorstenH. 4-Jul-13 9:38am

you are using Swing! that's my fault, you should look for a function repaint()...sorry for that.

The JComponent Class - painting components

Please browse through the tutorials and bookmark that stuff - all your questions should find an answer there as that is a fantastic tutorial.

Chiranthaka Sampath 4-Jul-13 11:27am

I have tried that as the below.

public void repaint() {
super.repaint(); //To change body of generated methods, choose Tools | Templates.
}
public void load(){

Student oStudent = new Student();

txtStudId.setText(oStudent.getStrStudName());
txtStudId.setText(oStudent.getStrStudNo());

txtTotal.setText(Double.toString(oStudent.calTotal()));
txtAverage.setText(Double.toString(oStudent.calAverage()));

txtGrade.setText(oStudent.findGrade());

repaint();

}

The result is the same and the 2nd UI didn't grab the data.

I also tried the following

JComponent.repaint( );

It didn't worked either.

I can't find any solution for that. Please try to give me more help. Thanks.

Chiranthaka Sampath 4-Jul-13 20:26pm

I have solved my problem and I posted it as an answer. If there are other ways to do this please enlighten me. But thank you
for the advices you have given. I really appreciate it.

Chiranthaka Sampath · Accepted Answer · 2013-07-04T14:22:00

I have solved my problem by using the static keyword. I changed all the variables in the Student class from non-static to static content
and also I changed all the getter () and setter () from non-static to static content.

Then the access of the variables and other methods are as the below.

Java

private void btnCalculateActionPerformed(java.awt.event.ActionEvent evt) {
       // TODO add your handling code here:

       Student.setStrStudNo(txtStudId.getText());
       Student.setStrStudName(txtStudName.getText());
       Student.setiMaths(Integer.parseInt(txtMaths.getText()));
       Student.setiScience(Integer.parseInt(txtScience.getText()));
       Student.setiEnglish(Integer.parseInt(txtEnglish.getText()));

       Student.calTotal();
       Student.calAverage();
       Student.findGrade();

       DisplayDetails oDisplayDet = new DisplayDetails();

       oDisplayDet.setVisible(true);

       JFrame oJFDisDet = new JFrame();

       oJFDisDet.getContentPane().add(new DisplayDetails());
       oJFDisDet.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       oJFDisDet.setSize(500, 500);
       oJFDisDet.setVisible(true);

   }


   private void load(){

     txtStudId.setText(Student.getStrStudNo());
     txtStudName.setText(Student.getStrStudName());

     txtTotal.setText(Double.toString(Student.calTotal()));
     txtAverage.setText(Double.toString(Student.calAverage()));

     txtGrade.setText(Student.findGrade());

     repaint();

   }

   public DisplayDetails() {
       initComponents();

       this.load();

   }

TorstenH. · Accepted Answer · 2013-07-07T07:44:00

Short solution.
I used one student and the Observer pattern[^] (*) , which makes it pretty slick.
You're welcome to play with it and extend the basic schema.

(*) bookmark that, Lars Vogel has pretty good tutorials.

Java

public class Application extends JFrame{

	private ShowPanel oShowPanel;
	private EnterPanel oEnterPanel;
	
	public Application(){
		super("Example");
		this.setDefaultCloseOperation(DISPOSE_ON_CLOSE);
		this.setSize(200, 300);
		this.ignition();
		this.setVisible(true); // makes itself visible
	}

	private void ignition() {
		this.setLayout(new GridLayout(2, 1));

		// create data object
		Student oStudent = new Student();
		// pass Object to JPanels
		oEnterPanel = new EnterPanel(oStudent);
		oShowPanel = new ShowPanel(oStudent);
		
		// Student is observed by ShowPanel
		oStudent.addObserver(oShowPanel);
		
		// add Panels to GUI
		this.add(oEnterPanel, 0);
		this.add(oShowPanel, 1);
	}

	/**
	 * <p>simple JPanel, which owns a text field and a button.<br>
	 * Clicking the button sets the name of the Object Student.</br></p>
	 */
	public class EnterPanel extends JPanel{

		public EnterPanel(Student oStudent){
			super();
			this.ignition(oStudent);
		}

		private void ignition(final Student oStudent) {
			this.setLayout(new GridLayout(3, 1));
			
			this.add(new JLabel("Enter name:"));
			final JTextField oText = new JTextField();
			this.add(oText);
			JButton oButton = new JButton("Click me hard!");
			oButton.addActionListener(new ActionListener() {
				@Override
				public void actionPerformed(ActionEvent oEvent) {
					oStudent.setName(oText.getText());
				}
			});
			this.add(oButton);
		}
	}
	
	/**
	 * <p>ShowPanel observes the data Object Student. <br>
	 * When notified, it updates the Label to present the name.</br></p>
	 */
	private class ShowPanel extends JPanel implements Observer {
		
		JLabel oLabel;
		public ShowPanel(Student oStudent){
			this.ignition(oStudent);
		}

		private void ignition(Student oStudent) {
			this.setLayout(new GridLayout(2, 1));
			this.add(new JLabel("Name is:"));
			
			oLabel= new JLabel();
			this.add(oLabel);
		}

		@Override
		public void update(Observable oObservable, Object oObject) {
			// we do not figure who kicked us, we just repaint.
			System.out.println("TEST");
			Student oStudent = ((Student)oObservable); // cast
			this.oLabel.setText(oStudent.getName()); // renew value
		}
	}
	
	/**
	 * <p>data Object, which holds the name of one student.<br>
	 * Classic POJO which extends Observable. The setter notifies the Observers.</br></p>
	 */
	public class Student extends Observable{
		private String strName;
		public Student() { /* doany() */}
		
		public void setName(String strName) {
			this.strName = strName;
			setChanged();
			notifyObservers();
		}

		public String getName() {
			return strName;
		}
	}
	
	// entry point
	public static void main(String[] args) {
		new Application(); // create Object
	}
}

Passing values between two JPanel forms in Java Swing.

3 solutions

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Passing values between two JPanel forms in Java Swing.

3 solutions

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