Java manual - Java Practicals Part 2

14.Write a program to handle Null Pointer Exception and use the “finally” method to display a message to the user. class NullException { public static void main (String[] args) { String ptr = null; try { if (ptr.equals("gfg")) System.out.print("Same"); else System.out.print("Not Same"); } catch(NullPointerException e) { System.out.println("Exception occurred in program: "); } finally { System.out.print(" NullPointer Exception ");} } } 15.Write a program which create and displays a message on the window import javax.swing.*; public class Window extends JFrame { JFrame frame; Window() { setTitle("Java Program"); JButton button = new JButton("Welcome to Java Lab"); button.setBounds(50, 50, 200,200 ); add(button); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); setSize(300, 300); setLayout(null); setVisible(true); } public static void main(String[] args) { new Window(); } } 16. Write a program to draw several shapes in the created window import java.awt.*; import javax.swing.JFrame; public class Shapes extends Canvas{ public void paint(Graphics g) { g.drawString("Hello",40,40); setBackground(Color.WHITE); g.fillRect(130, 30,100, 80); g.drawOval(10,130,50, 90); setForeground(Color.blue); g.fillOval(130,130,50, 60); } public static void main(String[] args) { Shapes m=new Shapes(); JFrame f=new JFrame(); f.add(m); f.setSize(400,400); f.setVisible(true); } } 17.Write a program to create an applet and draw grid lines import java.awt.Graphics; import javax.swing.JComponent; import javax.swing.JFrame; class GridLines extends JComponent { public void paint(Graphics g) { int rows = 20; int cols = 30; int width = getSize().width; int height = getSize().height; // draw the rows int rowHt = height / (rows); for (int i = 0; i < rows; i++) g.drawLine(0, i * rowHt, width, i * rowHt); // draw the columns int rowWid = width / (cols); for (int i = 0; i < cols; i++) g.drawLine(i * rowWid, 0, i * rowWid, height); } public class Demo { public static void main(String[] a) { JFrame window = new JFrame(); window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); window.setBounds(30, 30, 450, 450); window.getContentPane().add(new GridLines()); window.setVisible(true); } } } 18.Write a program which creates a frame with two buttons father and mother. When we click the father button the name of the father, his age and designation must appear. When we click mother similar details of mother also appear. import java.awt.*; import java.awt.GridLayout; import java.awt.event.*; import javax.swing.*; public class Parents extends JFrame { JButton Father,Mother; JLabel lbl; Parents() { Father = new JButton("Father"); Mother = new JButton ("Mother"); lbl = new JLabel (""); setSize (300,300); add(Father); add(Mother); Father.setBounds(10, 0, 100, 100); Mother.setBounds(130, 0, 100, 100); add(lbl); setVisible(true); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); ButtonHandler bh = new ButtonHandler(); Father.addActionListener(bh); Mother.addActionListener(bh); } class ButtonHandler implements ActionListener { public void actionPerformed(ActionEvent ae) { if (ae.getSource()==Father) { lbl.setText("Jayaram 60 Agriculturist"); } if (ae.getSource()==Mother) { lbl.setText("Suma 50 House Wife"); } } } public static void main(String args[]) { new Parents(); } } 19.Create a frame which displays your personal details with respect to a button click import java.awt.*; import java.awt.GridLayout; import java.awt.event.*; import javax.swing.*; public class Personal extends JFrame { JButton Button; JLabel lbl; Personal() { setTitle("My Details"); Button = new JButton("Details"); lbl = new JLabel (""); setSize (500,500); add(Button); Button.setBounds(150, 50, 80,80); add(lbl); setVisible(true); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); ButtonHandler bh = new ButtonHandler(); Button.addActionListener(bh); } class ButtonHandler implements ActionListener { public void actionPerformed(ActionEvent ae) { if (ae.getSource()==Button) { lbl.setText("Akhila S J"+" Lecture"+" KLE College"); Dept"+" } } } public static void main(String args[]) { new Personal(); } } 20. Create a simple applet which reveals the personal information of yours. import java.awt.*; import java.applet.*; import java.awt.event.*; public class PersonalDetailsApplet extends Applet implements Actionlistener { String s1=” “,s2=””; public void init() { BCA setLayout(null); setSize(400,300); Button btn=new Button(CLICK HERE FOR MY PERSONAL DETAILS”); add(btn); btn.setBounds(20,50,300,30); btn.addActionListener(this); } public void actionPerformed(ActionEvent e) { s1=”full name : Arjun “; s2=”college : KLE”; repaint(); public void paint (Graphics g) { g.setFont(new Font(“TimesRoman”,Font.BOLD,14)); g.drawString(s1,20,100); g.drawString(s2,20,100); } } 21. Write a program to move different shapes according to the arrow key pressed. 22.Write a java Program to create a window when we press M or m the window displays Good Morning, A or a the window displays Good After Noon E or e the window displays Good Evening, N or n the window displays Good Night import java.awt.event.KeyAdapter; import java.awt.event.KeyEvent; import javax.swing.JFrame; import javax.swing.JTextField; public class KeyBoardEvent { public static void main(String[] argv) throws Exception { JTextField textField = new JTextField(); textField.addKeyListener(new MKeyListener()); JFrame jframe = new JFrame(); jframe.add(textField); jframe.setSize(400, 350); jframe.setVisible(true); } } class MKeyListener extends KeyAdapter { public void keyPressed(KeyEvent event) { char ch = event.getKeyChar(); if (ch == 'm' ||ch == 'M' ) { System.out.println("Good Morning"); } else if (ch == 'A' ||ch == 'a' ) { System.out.println("Good Afternoon"); } else if (ch == 'e' ||ch == 'E' ) { System.out.println("Good Evening"); } else if (ch == 'n' ||ch == 'N' ) { System.out.println("Good Night"); } else { } } } 23.Demonstrate the various mouse handling events using suitable example. import java.awt.*; import java.awt.event.*; public class MouseEventpgm extends Frame implements MouseListener{ Label l; MouseEventpgm(){ addMouseListener(this); l=new Label(); l.setBounds(20,50,100,20); add(l); setSize(300,300); setLayout(null); setVisible(true); } public void mouseClicked(MouseEvent e) { l.setText("Mouse Clicked"); } public void mouseEntered(MouseEvent e) { l.setText("Mouse Entered"); } public void mouseExited(MouseEvent e) { l.setText("Mouse Exited"); } public void mousePressed(MouseEvent e) { l.setText("Mouse Pressed"); } public void mouseReleased(MouseEvent e) { l.setText("Mouse Released"); } public static void main(String[] args) { new MouseEventpgm(); } } 24.Write a program a. to create menu bar import java.awt.*; import javax.swing.JFrame; class MenuExample extends JFrame { MenuExample(){ Frame f= new Frame("Menu and MenuItem Example"); MenuBar mb=new MenuBar(); Menu menu=new Menu("Menu"); Menu submenu=new Menu("Print"); MenuItem i1=new MenuItem("New"); MenuItem i2=new MenuItem("Open"); MenuItem i3=new MenuItem("Save"); MenuItem i4=new MenuItem("Print Setup"); MenuItem i5=new MenuItem("Print Preview"); menu.add(i1); menu.add(i2); menu.add(i3); submenu.add(i4); submenu.add(i5); menu.add(submenu); mb.add(menu); f.setMenuBar(mb); f.setSize(400,400); f.setLayout(null); f.setVisible(true); } public static void main(String args[]) { new MenuExample(); } } b. to create pull down menu import javax.swing.*; import java.awt.event.*; public class PulldownMenu { JFrame f; PulldownMenu(){ f=new JFrame("Pull Down Menu Example"); final JLabel label = new JLabel(); label.setHorizontalAlignment(JLabel.CENTER); label.setSize(400,100); JButton b=new JButton("Show"); b.setBounds(200,100,75,20); String languages[]={"C","C++","C#","Java","PHP"}; final JComboBox cb=new JComboBox(languages); cb.setBounds(50, 100,90,20); f.add(cb); f.add(label); f.add(b); f.setLayout(null); f.setSize(350,350); f.setVisible(true); b.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { String data = "The Programming language Selected is: " cb.getItemAt(cb.getSelectedIndex()); label.setText(data); } } ); } public static void main(String[] args) { new PulldownMenu(); } } +