Contents | Prev | Next

Text fields

A TextField is a one line area that allows the user to enter and edit text. TextField is inherited from TextComponent, which lets you select text, get the selected text as a String, get or set the text, and set whether the TextField is editable, along with other associated methods that you can find in your online reference. The following example demonstrates some of the functionality of a TextField; you can see that the method names are fairly obvious:

//: TextField1.java
// Using the text field control
import java.awt.*;
import java.applet.*;

public class TextField1 extends Applet {
  Button
    b1 = new Button("Get Text"),
    b2 = new Button("Set Text");
  TextField 
    t = new TextField("Starting text", 30);
  String s = new String();
  public void init() {
    add(b1);
    add(b2);
    add(t);
  }
  public boolean action (Event evt, Object arg) {
    if(evt.target.equals(b1)) {
      getAppletContext().showStatus(t.getText());
      s = t.getSelectedText();
      if(s.length() == 0) s = t.getText();
      t.setEditable(true);
    }
    else if(evt.target.equals(b2)) {
      t.setText("Inserted by Button 2: " + s);
      t.setEditable(false);
    }
    // Let the base class handle it:
    else 
      return super.action(evt, arg);
    return true; // We've handled it here
  }
} ///:~

There are several ways to construct a TextField; the one shown here provides an initial string and sets the size of the field in characters.

Pressing button 1 either gets the text you’ve selected with the mouse or it gets all the text in the field and places the result in String s . It also allows the field to be edited. Pressing button 2 puts a message and s into the text field and prevents the field from being edited (although you can still select the text). The editability of the text is controlled by passing setEditable( ) a true or false.

Contents | Prev | Next