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Thread: please correct my programme on swings

  1. #1
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    Red face please correct my programme on swings

    import javax.swing.*;
    import java.awt.*;
    import javax.swing.border.*;
    class Mypanel extends JPanel
    {
    Mypanel()
    {
    this.setBackground(Color.pink);
    }
    public void paintComponent(Graphics g)
    {
    super.paintComponent(g);
    g.setColor(Color.black);
    g.setFont(new Font("Arial",Font.BOLD,10));
    g.drawString("click the buttons and get your favourite border ",100,20);
    }
    }
    class JBut extends JFrame
    {
    JButton b1,b2,b3,b4,b5,b6;
    JBut()
    {
    Container c=getContentPane();
    Mypanel p=new Mypanel();
    c.add(p);
    c.setLayout(new GridLayout());
    b1=new JButton("Raised Bevel Border");
    b1=new JButton("Lowered Bevel Border");
    b1=new JButton("Raised Etch Border");
    b1=new JButton("Raised Etch Border");
    b1=new JButton("Line Border");
    b1=new JButton("Empty Border");
    Border bd=BorderFactory.createBevelBorder(BevelBorder.RAI SED,Color.red,Color.green);
    b1.setBorder(bd);
    bd=BorderFactory.createBevelBorder(BevelBorder.LOW ERED,Color.red,Color.green);
    b2.setBorder(bd);
    bd=BorderFactory.createBevelBorder(EtchedBorder.RA ISED,Color.red,Color.green);
    b3.setBorder(bd);
    bd=BorderFactory.createBevelBorder(EtchedBorder.RA ISED,Color.red,Color.green);
    b4.setBorder(bd);
    bd=BorderFactory.createLineBorder(Color.red,5);
    b5.setBorder(bd);
    bd=BorderFactory.createEmptyBorder(10,10,10,10);
    b6.setBorder(bd);
    c.add(b1);
    c.add(b2);
    c.add(b3);
    c.add(b4);
    c.add(b5);
    c.add(b6);
    }
    public static void main(String[] args)throws NullPointerException
    {
    JBut j=new JBut();
    j.setSize(600,600);
    j.setTitle("border choosing frame");
    j.setVisible(true);
    j.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
    }
    ################################################## #########################################
    this is the run time error i am getting during running....... please help me out guyss!!!!!!
    Exception in thread "main" java.lang.NullPointerException
    at JBut.<init>(JBut.java:36)
    at JBut.main(JBut.java:54)


  2. #2
    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: please correct my programme on swings

    Look at line 36. Something is null there. Use print statements (or better yet, a debugger) to figure out what is null.

    Hint: Do you mean to set the same variable (b1) 6 different times?
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  3. #3
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    Default Re: please correct my programme on swings

    oh god what a silly mistake that was sory to waste your valuable time buddy...but thx yet ... i have another programme i will post it too..

  4. #4
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    Default Re: please correct my programme on swings

    import java.awt.*;
    import java.awt.event.*;
    class Allawt extends Frame implements ActionListener,ItemListener,AdjustmentListener
    {
    /**
    *
    */
    //private static final long serialVersionUID = 1L;
    String msg;
    Button b;
    Checkbox ch;
    CheckboxGroup cbg;
    Checkbox rb;
    Choice c;
    List lst;
    Scrollbar sc;
    TextField name;
    TextField password;
    Allawt()
    {
    try{
    //defining layout
    setLayout(new BorderLayout());

    //initializing components
    b=new Button();
    ch=new Checkbox("vja");
    c=new Choice();
    lst=new List(1,true);
    cbg=new CheckboxGroup();
    rb=new Checkbox("male",cbg,true);
    sc=new Scrollbar(Scrollbar.VERTICAL,0,30,0,500);
    Label n=new Label("Name:",Label.LEFT);
    Label p=new Label("Password:",Label.LEFT);
    //adding components
    add(b);
    add(ch);
    add(c);
    add(lst);
    add(rb);
    b.setBounds(10,20,30,30);
    b.setLabel("push me");
    ch.setLabel("vja");
    c.add("ferrari");
    c.add("bmw");
    lst.add("linux");
    lst.add("windows 7");
    add(sc);
    add(n);
    add(name);
    add(p);
    add(password);
    sc.setBounds(0,0,15,500);
    n.setBackground(Color.yellow);
    n.setForeground(Color.blue);
    password.setEchoChar('-');
    //assigning action listener to components

    b.addActionListener(this);
    ch.addItemListener(this);
    c.addItemListener(this);
    lst.addItemListener(this);
    rb.addItemListener(this);
    sc.addAdjustmentListener(this);
    name.addActionListener(this);
    password.addActionListener(this);
    //closing window function

    addWindowListener(new WindowAdapter()
    {
    public void windowClosing(WindowEvent e)
    {
    System.exit(0);
    }
    });

    }
    catch(Exception e)
    {
    e.printStackTrace();
    }
    }
    public void actionPerformed(ActionEvent ae)
    {
    System.out.println("button is pressed");
    }
    public void itemStateChanged(ItemEvent ie)
    {
    repaint();
    }
    public void adjustmentValueChanged(AdjustmentEvent ae)
    {
    repaint();
    }

    public void paint(Graphics g)
    {
    msg=b.getActionCommand();
    g.drawString("button pressed::"+msg,100,20);
    g.drawString("checkbox status:"+ch.getState(),100,40);
    msg=c.getSelectedItem();
    g.drawString("choice status:"+msg,100,60);
    msg=cbg.getSelectedCheckbox().getLabel();
    g.drawString("radio button status:"+msg,100,80);
    g.drawString("scrollbar position:"+sc.getValue(),200,100);
    msg=name.getText();
    g.drawString("name typed is:"+msg,200,120);
    msg=password.getText();
    g.drawString("password typed is:"+msg,200,140);
    }
    public static void main(String[] args)
    {
    Allawt f=new Allawt();
    f.setTitle("frame");
    f.setSize(1000,1000);
    f.setVisible(true);
    }
    }
    ################################################## #################################
    this is the runtime error.. i am a newbee to java
    java.lang.NullPointerException
    at java.awt.Container.addImpl(Unknown Source)
    at java.awt.Container.add(Unknown Source)
    at Allawt.<init>(Allawt.java:50)
    at Allawt.main(Allawt.java:113)
    Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at Allawt.paint(Allawt.java:106)
    at sun.awt.RepaintArea.paintComponent(Unknown Source)
    at sun.awt.RepaintArea.paint(Unknown Source)
    at sun.awt.windows.WComponentPeer.handleEvent(Unknown Source)
    at java.awt.Component.dispatchEventImpl(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Window.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
    at java.awt.EventQueue.access$000(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPri vilege(Unknown Sour
    ce)
    at java.security.ProtectionDomain$1.doIntersectionPri vilege(Unknown Sour
    ce)
    at java.awt.EventQueue$4.run(Unknown Source)
    at java.awt.EventQueue$4.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPri vilege(Unknown Sour
    ce)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilter s(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(U nknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarch y(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)

  5. #5
    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: please correct my programme on swings

    Again, look at that stack trace. It's telling you exactly what line the error is on: Allawt.paint(Allawt.java:106)

    What line is that? Have you used print statements or a debugger to figure out the values of each thing on that line?
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  6. #6
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    Default Re: please correct my programme on swings

    friend (Kevin Workman) please help me correct my code please

  7. #7
    Think of me.... Mr.777's Avatar
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    Default Re: please correct my programme on swings

    Quote Originally Posted by jeevan reddy mandali View Post
    friend (Kevin Workman) please help me correct my code please
    Can't you see, he is helping you?
    Just do as he asked you to do and you will be able to learn to solve this problem as well as many other problems related to programming.

  8. #8
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    Smile Re: please correct my programme on swings

    thx kevin and mr.777

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