Text Areas and Text Fields Component

The TextField and TextArea classes are two different Java classes for entering text data. The TextField class handles only one line of text. The TextArea class handles multiple lines. The example on this page illustrates text fields and a text echo. The following line will create a TextField with 20 columns.

plaintext.setText("Hello");

.
String mydata = plaintext.getText();

String thedata = plaintext.getSelectedText();

.

int first, last;
first = plaintext.getSelectionStart();
last = plaintext.getSelectionEnd();

plaintext.selectAll();

plaintext.setEchoCharacter('*');

.
.
char echosymbol =plaintext.getEchoChar();

.
int number = plaintext.getColumns();

Put text into the text field or text area.

Get the text that is in the text field.

Get the text that has been selected by the mouse.

Get the integers designating the first and last positions of the text.

Select the entire text.

For text fields only, set up an echo character which is printed instead of the text entered (such as those used when passwords are entered.)

Find out the echo character.

Find out how many visible columns there are.

The TextField class calls the action method when the user presses return. The TextArea class does not use the action method. The following example demonstrates the use of text fields

import java.applet.*;
import java.awt.*;

public class textfld extends Applet

{
 TextField plaintext = new TextField(20);
 TextField hiddentext = new TextField(10);
 Label plaintextvalue = new Label
   ("----------------------------------");
 Label hiddentextvalue = new Label
   ("-----------------------------------");

Import all the facilities of the AWT and applet that Java has to offer.

Create an applet textfld.

Create two text fields, with 20 and 10 columns, respectively. Create two labels containing lines.

  public void init()
  {
   add(new Label("Type text in either text
     box and hit the enter key."));
   add(plaintext);
   hiddentext.setEchoCharacter('*');
   add(hiddentext);
   add(new Label("Or hit this button to"));
   add(new Button("Enter both fields"));
   add(new Label("at once."));
   add(new Label("In the plain box you
     typed "));
   add(plaintextvalue);
   add(new Label("In the hidden box you
     typed "));
   add(hiddentextvalue);
  }

Add 5 labels and 2 text fields. The second text field, hiddentext, has '*' as an echo character. The plaintextvalue is added to one label when the event is handled. The hiddenttextvalue is added to the other label when the event is handled.

public boolean action(Event evt,
  Object whatAction)
  {
    if (evt.target == plaintext)    
     {
      plaintextvalue.setText
         (plaintext.getText());
      return true;
     }
    if (evt.target == hiddentext)
     {
      hiddentextvalue.setText
         (hiddentext.getText());
      return true;
     }
    if((evt.target instanceof Button))
     { 
	String buttonLabel = (String) 
            whatAction;
	if (buttonLabel == "Enter both
            fields")
	 {
	  hiddentextvalue.setText
              (hiddentext.getText());
	  plaintextvalue.setText
              (plaintext.getText());
	  return true;
	 }
     }
    return false;
  }
}

When a button is pressed or the user presses the enter key from within a text box an action event is triggered. The evt.target attribute will contain the type of action. If the action took place in the plain text box we get the text from plain text box and copy it to the plain text label and return true to indicate the event was handled.
We do the same for the hidden text box.

Finally check to see if the button was pressed.
If it is the button we want

Set the label for both the hidden and plain text values.
and return true to signal that the action was handled.

Return false if the text boxes or the button did not trigger this action.

The easiest way to obtain the code for this Applet is to click here and copy the contents of the screen that loads in your browser , paste it in a text editor and save it in a file called "textfld.java".

After compiling this program we need to create an HTML page with a reference to the class file. It will require a graphic window that is large enough to contain the two lists, buttons, and label (width-301 and height-301).