Text field and textarea

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TextField and TextArea

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On completion of this period, you would be able to know

• TextField• TextArea

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Objective

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Recap

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In the previous class, you have leant • Lists• Scroll bars

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TextField

• The TextField class implements a single-line text-entry area

• It is usually called an edit control• Text fields allow the user

– to enter strings – to edit the text using the arrow keys, cut and

paste keys, and mouse selections• TextField is a subclass of TextComponent

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• TextField defines the following constructors:– TextField( )– TextField(int numChars)– TextField(String str)– TextField(String str, int numChars)

– The first version creates a default text field– The second form creates a text field that is numChars

characters wide– The third form initializes the text field with the string

contained in str– The fourth form initializes a text field and sets its width

TextField contd..

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TextField contd..

• To obtain the string currently contained in the text field, call getText( )

• To set the text, call setText( )

• These methods are as follows– String getText( )– void setText(String str)– Here, str is the new

string

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• The other methods of interest are– String getSelectedText( )– void select(int startIndex, int endIndex)– boolean isEditable( )– void setEditable(boolean canEdit)– void setEchoChar(char ch)– boolean echoCharIsSet( )– char getEchoChar( )

TextField contd..

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Handling a TextField

• Let us see an example that creates the classic user name and password screen

// Demonstrate text field.

import java.awt.*;

import java.awt.event.*;

import java.applet.*;

/*<applet code="TextFieldDemo" width=380 height=150>

</applet>

*/

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public class TextFieldDemo extends Applet implements ActionListener {TextField name, pass;public void init() {

Label namep = new Label("Name: ", Label.RIGHT);Label passp = new Label("Password: ", Label.RIGHT);name = new TextField(12);pass = new TextField(8);pass.setEchoChar('?');add(namep);add(name);add(passp);add(pass);// register to receive action eventsname.addActionListener(this);pass.addActionListener(this);

}

Handling a TextField contd..

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// User pressed Enter.public void actionPerformed(ActionEvent ae) {

repaint();}public void paint(Graphics g) {

g.drawString("Name: " + name.getText(), 6, 60);g.drawString("Selected text in name: "+ name.getSelectedText(), 6, 80);g.drawString("Password: " + pass.getText(), 6, 100);

}}

Handling a TextField contd..

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• Here is the sample output

Handling a TextField contd..

Fig. 73.1 Output of TextFieldDemo

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TextArea

• Sometimes a single line of text input is not enough for a given task

• To handle these situations, the AWT includes a simple multiline editor called TextArea

• Following are the constructors for TextArea– TextArea( )– TextArea(int numLines, int numChars)– TextArea(String str)– TextArea(String str, int numLines, int numChars)– TextArea(String str, int numLines, int numChars, int Bars)

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TextArea contd..

• Here, – numLines specifies the height, in lines, of the

text area– numChars specifies its width, in characters – Initial text can be specified by str– In the fifth form you can specify the scroll bars

that you want the control to have

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TextArea contd..

• TextArea adds the following methods– void append(String str)– void insert(String str, int index)– void replaceRange(String str, int startIndex,

int endIndex)

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Example Program

// Demonstrate TextArea.import java.awt.*;import java.applet.*;/*<applet code="TextAreaDemo" width=300 height=250></applet>*/public class TextAreaDemo extends Applet {

public void init() {String val = "There are two ways of constructing " +"a software design.\n" +"One way is to make it so simple\n" +"that there are obviously no deficiencies.\n" +"And the other way is to make it so complicated\n" +"that there are no obvious deficiencies.\n\n" +" -C.A.R. Hoare\n\n" +

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"There's an old story about the person who wished\n" +"his computer were as easy to use as his telephone.\n" +"That wish has come true,\n" +"since I no longer know how to use my telephone.\n\n" +" -Bjarne Stroustrup, AT&T, (inventor of C++)";TextArea text = new TextArea(val, 10, 30);add(text);

}}

Example Program contd..

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• The output of TextAreaDemo is shown here

Fig. 73.2 Output of TextAreaDemo

Example Program contd..

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Summary

• We have discussed– TextField– TextArea components– The related program

• These components are useful for user text data entry

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Quiz

1. Which method TextField is used to show the effect of password

a) setPwdChar()

b) setEchoChar()

c) setPassword()

d) None

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Quiz contd..

2. Which component is useful for entering the address details(as a single unit) of a person ?

a) TextField

b) TextArea

c) Label

d) List

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Frequently Asked Questions

1. List and explain the methods of TextField

2. List the different constructors of TextArea

3. Write a Java program to accept the details of student like, PIN, Name, branch etc., in TextFields and show the same in labels

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