JTextArea

formatting text areas

Using JTextArea

JTextArea class is found in the javax.swing package.

Creates an text area that can process the escape formatting of \n and \t.

Can be used in showInputDialog and showMessageDialog methods taking the place of the String output parameter.

Example of JTextArea inputJTextArea outputArea = new JTextArea();int choice; do { String instructions ="Calculator for x and y " + "\nEnter your selection \n 1. Addition " + "\n 2. Subtraction \n 3. Multiplication " + "\n 4. Quit"; outputArea.setText(instructions); String choiceStr =

OptionPane.showInputDialog(outputArea);

Display of showInputDialog

Input

Calculator for x and yEnter your selection1. Addition2. Subtraction3. Multiplication4. Quit

OK Cancel

??

JTextArea sizeThe statement:

JTextArea outputArea = new JTextArea();Defaults the side of the text area to fit the

string to be displayed.Specify the size by using width and height JTextArea outputArea = new JTextArea(40,

100); Sets aside a 40 pixel width and 100 pixel

height area of text.

JTextArea set and append

Once the JTextArea object has been created with the new command, your code can initialize the text value in the JTextArea with the set method. You can add to the text by using the append method.

JTextArea set and append

JTextArea outputArea = new JTextArea();

outputArea.setText (“Title: 1 to 5”);for (int x = 1; x <= 5; ++x) outputArea.append(“\n” + x );outputArea.append(“\nTHE END”);JOptionPane.showMessageDialog(null, outputArea);

Input data

Array: numbers[0] to numbers[8]

Display the data

Sample of program import java.awt.Container; import javax.swing.*; public class lab91 extends JApplet {

double[] numbers; String output="";

public void init() { numbers = new double[9]; for (int i = 0; i < 9; i++) { numbers[i] = Double.parseDouble(JOptionPane.showInputDialog( "Enter a floating-point value" )); }

for (int i = 0; i < 9; i++) { output += "number" + (i + 1) +": "+numbers[i]+"\n"; }

JTextArea outputArea = new JTextArea(150, 300); outputArea.setText( output); Container container = getContentPane(); container.add( outputArea );

} // end method init

}

Bubble Sort

Bubble – use the previous template

Sample

Question 2 – Rational

Question 2 – Rational

Output

Output

Rational – Add

Rational – Compare

Rational – Common divisor

Test Driver - input

Test driver – case 1

Test driver – case 2

Test Driver – case 3

Software import java.applet.*; import java.awt.*; import javax.swing.*;

public class GUIRationalDriver extends JApplet { public void init() {

String input,output; int choice;

input = JOptionPane.showInputDialog( "Enter 1 to test reduce() method\n" + "Enter 2 to test equal() method\n" + "Enter 3 to test add() method\n");

choice = Integer.parseInt( input );

switch ( choice ) {

case 1: { Rational r1; int a = Integer.parseInt(JOptionPane.showInputDialog( "Enter numerator of Rational" )); int b = Integer.parseInt(JOptionPane.showInputDialog( "Enter denominator of Rational" )); ......................

} break; case 2: { Rational r1,r2; int a = Integer.parseInt(JOptionPane.showInputDialog( "Enter numerator of First Rational" )); int b = Integer.parseInt(JOptionPane.showInputDialog( "Enter denominator of First Rational" )); int c = Integer.parseInt(JOptionPane.showInputDialog( "Enter numerator of Second Rational" )); int d = Integer.parseInt(JOptionPane.showInputDialog( "Enter denominator of Second Rational" ));

............................ } break; // done processing case

case 3: { Rational r1,r2; int a = Integer.parseInt(JOptionPane.showInputDialog( "Enter numerator of First Rational" )); int b = Integer.parseInt(JOptionPane.showInputDialog( "Enter denominator of First Rational" )); int c = Integer.parseInt(JOptionPane.showInputDialog( "Enter numerator of Second Rational" )); int d = Integer.parseInt(JOptionPane.showInputDialog( "Enter denominator of Second Rational" ));

..................

} break; // done processing case default: output = "Invalid value entered"; } // end switch JOptionPane.showMessageDialog( null, output, "Results", JOptionPane.INFORMATION_MESSAGE ); } }