Want to win a PS4? Go Premium and enter to win our High-Tech Treats giveaway. Enter to Win

x
?
Solved

NullPointException error don't see it

Posted on 2004-04-02
7
Medium Priority
?
215 Views
Last Modified: 2010-03-31
It happen here:  add(jLabel1);  jLabel1.setText("Defensive Moves"); setBackground(Color.white);




import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;

public class MyClass4 extends JPanel {
  JLabel jLabel1;  
 
  ArrayList myArrayList = new ArrayList();

// Constructor
public MyClass4() {

    setLayout(new GridLayout(0,3)); // Setting MY layout...

add(jLabel1);  jLabel1.setText("Defensive Moves"); setBackground(Color.white);

    looprow:
        for (int row=0; row<20; row++) {
            for(int col=0; col<3; col++) {
                int n=(20*col+row+1);
                if (n>50) break looprow;
                JCheckBox check = new JCheckBox("" + n);

            myArrayList.add(check);
add(check); // Adding it to ME
}
}
}
}
0
Comment
Question by:Drop_of_Rain
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
  • 2
  • 2
  • +1
7 Comments
 
LVL 92

Accepted Solution

by:
objects earned 400 total points
ID: 10746541
jLabel1 is null.

Change declaration to:
  JLabel jLabel1 = new JLabel();  
0
 
LVL 92

Expert Comment

by:objects
ID: 10746586
0
 
LVL 15

Expert Comment

by:Javatm
ID: 10746589
Friend;

You need to also call the jLabel after you had declared it like :

import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;

public class MyClass4 extends JPanel {

  JLabel jLabel1;  
  ArrayList myArrayList = new ArrayList();

public MyClass4() {

     // Call it like this . . .
    jLabel = JLabel();

    setLayout(new GridLayout(0,3)); // Setting MY layout...
 
    add(jLabel1);  
    jLabel1.setText("Defensive Moves");
    setBackground(Color.white);

    looprow:
    for (int row=0; row<20; row++) {
    for(int col=0; col<3; col++) {
    int n=(20*col+row+1);
    if (n>50) break looprow;
    JCheckBox check = new JCheckBox("" + n);

    myArrayList.add(check);
    add(check);
    }
    }
}
}

Hope that helps . . .
Javatm
0
Concerto's Cloud Advisory Services

Want to avoid the missteps to gaining all the benefits of the cloud? Learn more about the different assessment options from our Cloud Advisory team.

 
LVL 15

Expert Comment

by:Javatm
ID: 10746614
Your 2 fast you think you havent seen my solution.
0
 

Author Comment

by:Drop_of_Rain
ID: 10746654
Error can't resolve method jLabel1()



import java.awt.event.*;
import java.util.*;
import javax.swing.*;

public class MyClass4 extends JPanel {

  JLabel jLabel1;  
  ArrayList myArrayList = new ArrayList();

public MyClass4() {

     // Call it like this . . .
    jLabel = JLabel();

    setLayout(new GridLayout(0,3)); // Setting MY layout...
 
    add(jLabel1);  
    jLabel1.setText("Defensive Moves");
    setBackground(Color.white);

    looprow:
    for (int row=0; row<20; row++) {
    for(int col=0; col<3; col++) {
    int n=(20*col+row+1);
    if (n>50) break looprow;
    JCheckBox check = new JCheckBox("" + n);

    myArrayList.add(check);
    add(check);
    }
    }
}
}
0
 
LVL 5

Expert Comment

by:twobitadder
ID: 10747819
jLabel = JLabel();

should be

jLabel = new JLabel();   //to initialise a new JLabel you use the new operator.
0
 
LVL 5

Expert Comment

by:twobitadder
ID: 10747824
it should be jLabel1 = new jLabel() actually, you don't have any object called jlabel
0

Featured Post

Concerto's Cloud Advisory Services

Want to avoid the missteps to gaining all the benefits of the cloud? Learn more about the different assessment options from our Cloud Advisory team.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Are you developing a Java application and want to create Excel Spreadsheets? You have come to the right place, this article will describe how you can create Excel Spreadsheets from a Java Application. For the purposes of this article, I will be u…
In this post we will learn how to connect and configure Android Device (Smartphone etc.) with Android Studio. After that we will run a simple Hello World Program.
Viewers will learn about the different types of variables in Java and how to declare them. Decide the type of variable desired: Put the keyword corresponding to the type of variable in front of the variable name: Use the equal sign to assign a v…
This video teaches viewers about errors in exception handling.
Suggested Courses

610 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question