AWT-Abstract Window Toolkit

Class TextField

• This component allows the user to read single line of text or Password.

• TextField()
• Constructs a new TextField
For ex: txt=new TextField();
• TextField(int columns)
• Constructs a new empty text field of specified char width.
For ex: txt=new TextField(50);
• TextField(String text)
• Constructs a new text field with the specified text.
For ex: txt=new TextField("CCIT");

• TextField(String text, int columns)
• Constructs a new text field with the specified text and of specified char width.
For ex: txt=newTextField("CCIT",50);

• void setEchoChar(char c)
• Sets the echo character for this text field.
For ex:txt.setEchoChar('*');
• void addActionListener(ActionListener l)
• It will register an action listener for textfield .
• Due to which notifications will be send to listener x when enter key is pressed in textfield.
For ex:txt.addActionListener(x);

TextField Hierarchy

Class TextComponent

• This class is superclass of TextField and TextArea.

• String getText()
• Returns the text of text components.
For ex:String data=txt.getText();
• void setText(String t)
• Returns the text of text component.
For ex:String data=txt.getText();

• void setEditable(boolean b)
• Sets the flag that determines whether or not this text component is editable.
For ex:txt.setEditable(false);
• void select(int selectionStart, int selectionEnd)
• Selects the text between the specified start(including) and end positions(excluding).
For ex:txt.select(2,5);
• Void selectAll()
• Selects all the text in this text component.
For ex:txt.selectAll();
• String getSelectedText()
• Returns the selected text.
For ex:String data=txt.getSelectedText();
• int getSelectionStart()
• Gets the start position of the selected text.
For ex:int n1=txt.getSelectionStart();
• int getSelectionEnd()
• Gets the end position of the selected text.
For ex:int n2=txt.getSelectionEnd();

 import java.awt.*;
 import java.awt.event.*;
 class MyFrame extends Frame implements ActionListener
 {
    TextField t1,t2;
    Button b1;
    public MyFrame()
    { 
        setLayout(new FlowLayout());
        t1=new TextField(10);
        t2=new TextField(10);
        b1=new Button("Exchange");
        b1.addActionListener(this);
        add(t1);
        add(b1);
        add(t2);
    }
    public void actionPerformed(ActionEvent e)
    {
        String d1=t1.getText();
        String d2=t2.getText();
        t1.setText(d2);
        t2.setText(d1); 
    }
 }
 class demo
 {
    public static void main(String args[])
    {
        MyFrame frm=new MyFrame();
        frm.setVisible(true);
        frm.setSize(400,300);
    }
 }

 import java.awt.*;
 import java.awt.event.*;
 class MyFrame extends Frame implements ActionListener
 {
    TextField t1;
    Button b1,b2;
    public MyFrame()
    { 
        setLayout(new FlowLayout());
        t1=new TextField(10);
        b1=new Button("Increment");
        b2=new Button("Decrement");
        b1.addActionListener(this);
        b2.addActionListener(this);
        add(b1);
        add(t1);
        add(b2);
    }
    public void actionPerformed(ActionEvent e)
    {
        int n=Integer.parseInt(t1.getText()); 
        if(e.getSource()==b1)
            n=n+1;
        else 
            if(e.getSource()==b2)
                n=n-1;
        t1.setText(String.valueOf(n));
    }
 }
 class demo
 {
    public static void main(String args[])
    {
        MyFrame frm=new MyFrame();
        frm.setSize(400,300);
        frm.setVisible(true);
    }
 }