about Textfield( simple isn't that)

[Surya Prabhakar]

Hello friends!!!..,
I hope u can answer this.
1) In a text field the default alignment of the cursor is right side.Can we align it to the left side?
2) Unlike that can we make cursor invisible in the textfield but still the text can be entered from left?
3)can we restrict the textfield to accept only numbers?

Please answer me these q? I need to work on a project
thank u

[Roshini Sridharan]

Try this coding to allow no's in the textfield.
class test
{
public void add()
{
TextField no = new TextField(20);
no.addFocusListener(new listener());
}
class listener extends FocusAdapter
{
public void focusLost(FocusEvent fe)
{
int val = 0;
if(ae.getSource().equals(no))
{
try{
val = Integer.parseInt(no.getText());
}
catch(NumberFormatException ne){--codes to show error msg--}
}
}
}
-----
-----
}

RoshiniSridharan

[Surya Prabhakar]

Thank you Mr/Miss RoshiniSridharan for ur enthusiastic reply.But I think I should explain u the concept in detail actually I mean to say that ,consider the textfield as a display screen for calculator,in which text should not at all come,take example of a windows calculator in which all text keys are disabled so that no text can be entered.Your code is good enough but only verified after entering something into the textfield,which should not be allowed.so I hope u understand the problem.
thx again
bye

[Cindy Glass]

If you attach a KeyListener to the textField and have it check for keyPressed (this is before keyReleased happens) then you should be able to "catch" the char, check it for numeric and if it is alpha substitute a null.

 component.addKeyListener(new MyKeyListener());
                          
                      public class MyKeyListener extends KeyAdapter {
                        public void keyPressed(KeyEvent evt) {
                          // Check for key characters.
                          if (evt.getKeyChar() == VK_AkeyCode) {
                            evt.setKeyChar(null);
                          }
                          
                         }
                        }
                      }

Here is a whole tutorial on keyEvents: http://java.sun.com/docs/books/tutorial/uiswing/events/example-swing/KeyEventDemo.java

[deekasha gunwant]

hi Surya,
If u r talking about JTextField then i'd like suggest yet another way to do so.i.e. use PlainDocument class.
here is the example code

[B] NumericDocument.java [/B]
--------------------------
import javax.swing.text.*;
class NumericDocument extends PlainDocument
{
int docLength = 5;
NumericDocument()
{
super();
    }
    public void insertString(int offs,
                         String str,
                         AttributeSet a)
                  throws BadLocationException
   {
      // check if offset exceeds the no. of digits allowed
   if(offs>=docLength)
   {
   return;
   }
   try
   {
      Integer.parseInt(str);
       }
       catch(NumberFormatException nfe)
       {
   System.out.println("Non numeric value.... ");
   return;
   }
      //  string is a number so insert in to textfield
   super.insertString(offs,str,a);
   }

}
--------------------------
[B] PlainDocTest.java [/B]
-------------------------------
import javax.swing.*;
import javax.swing.text.*;
import java.awt.event.*;
import java.awt.*;
class PlainDocTest extends JFrame
{
   JTextField jtf = new JTextField(new NumericDocument(),"123",20);
   Container  container = getContentPane();
   PlainDocTest()
   {
     container.setLayout(new FlowLayout());
     container.add(jtf);

   }
   public static void main(String s[])
   {
      PlainDocTest fr = new PlainDocTest();
      fr.setSize(300,300);
      fr.setVisible(true);
   }
}
-------------------------------
  

regards
deeksha

[Suneel Setlur]

Hey Surya
You can check the solution posted here.
http://www.javaranch.com/ubb/Forum23/HTML/000437.html
Suneel