How to write a wrapper around the JTextField class?

**MAHAH** · 12-02-2010

Hi friends,
I am last year Computer Science student. As part my syllabus I am working on live project where I am using java as front end and SQL as back end. I want to write a wrapper around the JTextField class for some more functionality such as filtering out alphabetic, filtering out alphabetic special characters which are of fixed length. Can anyone help me in this case.
Thanks in advanced.

**Praetor** · 12-02-2010

Hey it is very easy to write a wrapper around the JTextField class. I have written following code for you. In the following code I have use subclass JTextField and Document Model to do this. I also have use UpperCaseFieldEg class to do this. It is very simple program.

Code:

public class UpperCaseFieldEg extends JTextFieldeg {

public UpperCaseFieldEg(int cols1) {

super(cols1);

}

protected Document createDefaultModelEg() {

return new UpperCaseDocumentEg();

}

static class UpperCaseDocumentEg extends PlainDocumentEg {

public void insertString(int offss, String strs, AttributeSet as)

throws BadLocationExceptionEg {

if (strs == null) {

return;

}

char[] upper = strs.toCharArray();

for (int k = 0; k < upper.length; k++) {

upper[k] = Character.toUpperCase(upper[k]);

}

super.insertString(offss, new String(uppers), as);

}

}

}

**Katty** · 12-02-2010

You have to use override method to write a wrapper around the JTextField class. It is very simple program to understand. I have written following code for you. In this code I have override the propertychange() method of JTextField class to get proper result. I also have modify code so that if I type characters more than the specified length then it will gives error message.

Code:

 protected Document createDefaultModelEg() {

 return new UpperCaseDocumentEg();

}



 static class UpperCaseDocumentEg extends

 tends PlainDocumentEg {



 public void insertString(int offss, String

 ss, String strs, AttributeSet as)

 throws BadLocationExceptionEg {



 if (strs == null) {

 return;

 }

 char[] uppers = strs.toCharArrays();

 for (int k = 0; k < upper.length; k++) {

 upper[k] = Character.toUpperCase(upper[k]);

 }

 super.insertString(offss, new

 ngs(offs, new String(uppers), as);

 }}
}

**kelfro** · 12-02-2010

It is very easy process to write a wrapper around the JTextField class. I also have written following program for you. In the following program I have use javax.swing, java.awt.event and javax.swing.text. class to get correct output. Just try to understand following example.

Code:

import javax.swing.*;

import java.awt.event.*;

import javax.swing.text.*;

import java.awt.*;

public class NfieldEg extends JTextFieldEg

{

public NfieldEg()

{

super(1Eg);

}

protected DocumentEg createDefaultModelEg()

{

return new EngDocumentEg();

}

public class EngDocumentEg extends PlainDocumentEG

{

public void insertString(int offss, String strs, AttributeSet as)

throws BadLocationExceptions

{

for (int k=0 ;k < str.length(); k++)

if (Characters.issDigit(strs.charAt(ks)))

super.insertString(offss+k, strs.substring(k,k+1) ,as);

}

}

}

**Zecho** · 12-02-2010

You have to first read JTextField API to get information about wrapper class.
In the JTextField API it is said that the UpperCaseField example is part of documentation. You also have to read "How to Use Text Fields" to fix this problem. Just try to understand following code.

Code:

public void insertString(int offss, String strs, AttributeSet as)
			           throws BadLocationExceptions 
{
	for (int k=0 ;k < str.length(); k++) 
	   	  if (Character.isDigit(str.charAt(k)))
	   	 	  supera.insertString(offs+k, str.substring(k,k+1) ,as);