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Sep 15th, 2009

Centering Issues

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I'm toying around with Java trying to familiarize myself with the basic GUI stuff. I can't get my program or my text field inside of it to center on the screen.

For the Simple... file, I've tried using the

Java Syntax (Toggle Plain Text)
theTextArea.setLocation(15, 30);
theTextArea.setLocation(15, 30);

and

Java Syntax (Toggle Plain Text)

//theTextArea.setAlignmentX(CENTER_ALIGNMENT);
          //theTextArea.setAlignmentY(CENTER_ALIGNMENT);

seperately. When I have either of them as active code and not comments, it throws an error and won't even run the program. What am I missing here?

Java Syntax (Toggle Plain Text)
//mainForSimpleGUI.java
 
import javax.swing.*;
import java.awt.*;
 
public class mainForSimpleGUI
{
    public static void main(String[] args)
    {
        SimpleJavaGUI labelFrame = new SimpleJavaGUI(); //creates SimpleJavaGUI
        //labelFrame = new JLabel();
        labelFrame.setLocationRelativeTo(null);
        labelFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        labelFrame.setSize(300, 300);
        labelFrame.setVisible(true);
    }
 
}
//mainForSimpleGUI.java

import javax.swing.*;
import java.awt.*;

public class mainForSimpleGUI
{
    public static void main(String[] args)
    {
        SimpleJavaGUI labelFrame = new SimpleJavaGUI(); //creates SimpleJavaGUI
        //labelFrame = new JLabel();
        labelFrame.setLocationRelativeTo(null);
        labelFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        labelFrame.setSize(300, 300);
        labelFrame.setVisible(true);
    }

}

Java Syntax (Toggle Plain Text)
//SimpleJavaGUI.java
 
import java.awt.*;
import javax.swing.*;
 
 
public class SimpleJavaGUI extends JFrame
{
    private JTextArea theTextArea;
 
    public SimpleJavaGUI()
    {
        super("mainForSimpleGUI");
        setLayout(new FlowLayout() );
 
        theTextArea.setLocation(15, 30);
        //theTextArea.setAlignmentX(CENTER_ALIGNMENT);
        //theTextArea.setAlignmentY(CENTER_ALIGNMENT);
        theTextArea = new JTextArea(2, 20);
        theTextArea.setText(" Follow the white rabbit.");
        theTextArea.setToolTipText("This is a text area.");
        theTextArea.setEditable(false);
        theTextArea.setDisabledTextColor(Color.BLACK);
        theTextArea.setLineWrap(true);
        theTextArea.setBorder(BorderFactory.createLineBorder(Color.black) );
        add(theTextArea);
    }
}
//SimpleJavaGUI.java

import java.awt.*;
import javax.swing.*;


public class SimpleJavaGUI extends JFrame
{
    private JTextArea theTextArea;

    public SimpleJavaGUI()
    {
        super("mainForSimpleGUI");
        setLayout(new FlowLayout() );

        theTextArea.setLocation(15, 30);
        //theTextArea.setAlignmentX(CENTER_ALIGNMENT);
        //theTextArea.setAlignmentY(CENTER_ALIGNMENT);
        theTextArea = new JTextArea(2, 20);
        theTextArea.setText(" Follow the white rabbit.");
        theTextArea.setToolTipText("This is a text area.");
        theTextArea.setEditable(false);
        theTextArea.setDisabledTextColor(Color.BLACK);
        theTextArea.setLineWrap(true);
        theTextArea.setBorder(BorderFactory.createLineBorder(Color.black) );
        add(theTextArea);
    }
}

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kahaj

Reputation Points: 10

Solved Threads: 0

Junior Poster

Offline

193 posts
since Sep 2005

Permalink

Sep 15th, 2009

Re: Centering Issues

Use line 19 before 16 and 17. You are not initializing the theTextArea.

Majestics

Reputation Points: 188

Solved Threads: 44

Posting Pro

Offline

554 posts
since Jul 2007

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Sep 15th, 2009

Re: Centering Issues

Okay, I changed that. For whatever reason, it's not showing the text area at all now. Here's how it looks now (I commented out any location-oriented lines just to try and "dumb" it down and figure out why my text area vanished):

Java Syntax (Toggle Plain Text)
//SimpleJavaGUI.java
 
import java.awt.*;
import javax.swing.*;
 
 
public class SimpleJavaGUI extends JFrame
{
    private JTextArea theTextArea;
 
    public SimpleJavaGUI()
    {
        super("mainForSimpleGUI");
        setLayout(new FlowLayout() );
 
        theTextArea = new JTextArea(2, 15);
        theTextArea.setLocation(50, 50);
        //theTextArea.setAlignmentX(CENTER_ALIGNMENT);
        //theTextArea.setAlignmentY(CENTER_ALIGNMENT);
        theTextArea.setText(" Follow the white rabbit.");
        theTextArea.setToolTipText("This is a text area.");
        theTextArea.setEditable(false);
        theTextArea.setDisabledTextColor(Color.BLACK);
        theTextArea.setLineWrap(true);
        theTextArea.setBorder(BorderFactory.createLineBorder(Color.black) );
        add(theTextArea);
    }
}
//SimpleJavaGUI.java

import java.awt.*;
import javax.swing.*;


public class SimpleJavaGUI extends JFrame
{
    private JTextArea theTextArea;

    public SimpleJavaGUI()
    {
        super("mainForSimpleGUI");
        setLayout(new FlowLayout() );

        theTextArea = new JTextArea(2, 15);
        theTextArea.setLocation(50, 50);
        //theTextArea.setAlignmentX(CENTER_ALIGNMENT);
        //theTextArea.setAlignmentY(CENTER_ALIGNMENT);
        theTextArea.setText(" Follow the white rabbit.");
        theTextArea.setToolTipText("This is a text area.");
        theTextArea.setEditable(false);
        theTextArea.setDisabledTextColor(Color.BLACK);
        theTextArea.setLineWrap(true);
        theTextArea.setBorder(BorderFactory.createLineBorder(Color.black) );
        add(theTextArea);
    }
}

kahaj

Reputation Points: 10

Solved Threads: 0

Junior Poster

Offline

193 posts
since Sep 2005

Permalink

Sep 16th, 2009

Re: Centering Issues

Java Syntax (Toggle Plain Text)
 
import javax.swing.*;
 
import java.awt.*;
 
  public class mainForSimpleGUI
  {
      public static void main(String[] args)
      {
          SimpleJavaGUI labelFrame = new SimpleJavaGUI(); 
          labelFrame = new SimpleJavaGUI();
          labelFrame.setLocationRelativeTo(null);
          labelFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          labelFrame.setSize(300, 300);
          labelFrame.setVisible(true);
      }
 
  }
 
    @SuppressWarnings("serial")
	class SimpleJavaGUI extends JFrame
  {
      public  JTextArea theTextArea;
 
      public SimpleJavaGUI()
      {
          super("mainForSimpleGUI");
          setLayout(new FlowLayout() );
          theTextArea = new JTextArea(2, 20);
          theTextArea.setLocation(15, 30);
          theTextArea.setAlignmentX(CENTER_ALIGNMENT);
          theTextArea.setAlignmentY(CENTER_ALIGNMENT);
 
          theTextArea.setText(" Follow the white rabbit.");
          theTextArea.setToolTipText("This is a text area.");
          theTextArea.setEditable(false);
          theTextArea.setDisabledTextColor(Color.BLACK);
          theTextArea.setLineWrap(true);
          theTextArea.setBorder(BorderFactory.createLineBorder(Color.black) );
          add(theTextArea);
      }
  }
 
import javax.swing.*;

import java.awt.*;
   
  public class mainForSimpleGUI
  {
      public static void main(String[] args)
      {
          SimpleJavaGUI labelFrame = new SimpleJavaGUI(); 
          labelFrame = new SimpleJavaGUI();
          labelFrame.setLocationRelativeTo(null);
          labelFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          labelFrame.setSize(300, 300);
          labelFrame.setVisible(true);
      }
   
  }

    @SuppressWarnings("serial")
	class SimpleJavaGUI extends JFrame
  {
      public  JTextArea theTextArea;
   
      public SimpleJavaGUI()
      {
          super("mainForSimpleGUI");
          setLayout(new FlowLayout() );
          theTextArea = new JTextArea(2, 20);
          theTextArea.setLocation(15, 30);
          theTextArea.setAlignmentX(CENTER_ALIGNMENT);
          theTextArea.setAlignmentY(CENTER_ALIGNMENT);
          
          theTextArea.setText(" Follow the white rabbit.");
          theTextArea.setToolTipText("This is a text area.");
          theTextArea.setEditable(false);
          theTextArea.setDisabledTextColor(Color.BLACK);
          theTextArea.setLineWrap(true);
          theTextArea.setBorder(BorderFactory.createLineBorder(Color.black) );
          add(theTextArea);
      }
  }

I applied this and it is showing me the text area.

Majestics

Reputation Points: 188

Solved Threads: 44

Posting Pro

Offline

554 posts
since Jul 2007

Permalink

Sep 16th, 2009

Re: Centering Issues

Okay, what options are available to center items within a JFrame? I thought for sure that the setAlignmentX/Y would work for it. I don't understand why they're not working.

kahaj

Reputation Points: 10

Solved Threads: 0

Junior Poster

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193 posts
since Sep 2005

This thread is more than three months old

No one has posted to this discussion for at least three months. Please let old threads die and do not reply to them unless you feel you have something new and valuable to contribute that absolutely must be added to make the discussion complete. Otherwise, please start a new thread in this forum instead.

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