Error java awt

ANSWER:

If you ever see these lines and are mistified like I was, here’s what they mean.

Thread[AWT-EventQueue-0] (Suspended (exception NullPointerException))

EventDispatchTread.run() line: not available [local variables unavailable]

It’s not that the variables are unavailable because they are lurking behind a shroud of mystery in a library somewhere dank. No no, they just went out of scope! It’s still your fault, you still have to find the null, and no you can’t blame the library. Important lesson!

QUESTION:

One of the most frustrating things for me, as a beginner is libraries! It’s a love/hate relationship: On the one hand they let me do things I wouldn’t normally understand how to do with the code that I do understand, on the other hand because I don’t completely understand them, they sometimes throw a wrench in code that is otherwise working fine! It’s because I don’t understand the errors that can occur when using these libraries, because I didn’t write them, and because eclipse doesn’t give me a great deal to go with when one of imports starts acting up…

So here’s the problem: I’ve been working with java.awt.event to handle a bunch of JButtons on the screen for this and that. I get an error when I use one of the buttons I’ve made. The error is:

Thread[AWT-EventQueue-0] (Suspended (exception NullPointerException))

EventDispatchTread.run() line: not available [local variables unavailable]

What does this mean? What could be causing it? I’m embarrassed to post code, but if you can stand to try to decipher my terrible style, here is the method that seems to cause this error to be thrown.

public void actionPerformed(ActionEvent e) {
    String cmd = e.getActionCommand();
    String name;

code...

if(cmd.equals("Play")) {
        name = field.getText();
        card = getCard(name);
        
        if(card != null) {
            if(rules.zoneHasCard(card, rules.hand)) {
                display.updateStatusMessage(rules.play(card));
                field.setText("");
                display.updateHand(rules.zoneList("hand"));
                display.updateDiscard(rules.zoneList("Discard")); // This is the error here! The discard Zone was empty!
            }
            else {
                field.setText("You do not have " + card.getName());
                field.selectAll();
            }
        }
        else {
            field.setText("That cardname is unused");
            field.selectAll();
        }
    }
}

Issue

Since I’m new to java, I couldn’t figure out why this error occurred and how to resolve it.

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package Code;

import javax.swing.JTable;

/**
 *
 * @author Regan
 */
public class Report extends javax.swing.JFrame {

    /**
     * Creates new form Report
     */
    public Report() {
        initComponents();
       for(int i=0;i<Auditor.report.size();i++)
    System.out.println(Auditor.report.get(i));
        String column[]={"Fragment ID","Status"};  
        String[][] data=new String[Auditor.report.size()+1][2]; 
        data[0][0]="Fragment ID";
        data[0][1]="Status";
         for(int i=0;i<Auditor.report.size();i++)
            for(int j=0;j<Auditor.report.get(i).size();j++)
                data[i+1][j]=Auditor.report.get(i).get(j);
        JTable jt=new JTable(data,column);    
    jt.setBounds(30,40,200,300);
    jPanel1.add(jt);
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">//GEN-BEGIN:initComponents
    private void initComponents() {

        jLabel1 = new javax.swing.JLabel();
        jPanel1 = new javax.swing.JPanel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        getContentPane().setLayout(new org.netbeans.lib.awtextra.AbsoluteLayout());

        jLabel1.setFont(new java.awt.Font("Lucida Bright", 1, 36)); // NOI18N
        jLabel1.setForeground(new java.awt.Color(169, 11, 63));
        jLabel1.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        jLabel1.setText("AUDITING REPORT");
        getContentPane().add(jLabel1, new org.netbeans.lib.awtextra.AbsoluteConstraints(0, 0, 500, 50));

        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 470, Short.MAX_VALUE)
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 390, Short.MAX_VALUE)
        );

        getContentPane().add(jPanel1, new org.netbeans.lib.awtextra.AbsoluteConstraints(10, 90, 470, 390));

        pack();
    }// </editor-fold>//GEN-END:initComponents

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(Report.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(Report.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(Report.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(Report.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new Report().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify//GEN-BEGIN:variables
    private javax.swing.JLabel jLabel1;
    private javax.swing.JPanel jPanel1;
    // End of variables declaration//GEN-END:variables
}

The above code causing the error but I’m still confused at whether it’s a IDE error or my code error. This error happens on both Visual Studio code and NetBeans

1. What are the possible causes of a java.lang.Error: Unresolved compilation problem?
2. Whether IDE is the only problem?

Traceback:

Exception in thread "AWT-EventQueue-0" java.lang.Error: Unresolved compilation problems: 
        org.netbeans cannot be resolved to a type
        org.netbeans cannot be resolved to a type
        org.netbeans cannot be resolved to a type

        at Code.Report.initComponents(Report.java:48)
        at Code.Report.<init>(Report.java:20)
        at Code.Report$1.run(Report.java:102)
        at java.desktop/java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:316)
        at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:770)
        at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:721)
        at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:715)
        at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
        at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
        at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:740)
        at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
        at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
        at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
        at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
        at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
        at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)

Any kind of help is to be thankful

Solution

1. What are the possible causes of a java.lang.Error: Unresolved compilation error problem?

This means you have a compilation error in your source code somewhere, and you have tried run the code without fixing the compilation error(s).

The error message in the exception is saying that there is an error in Code.Report class. Apparently, the code trying to use something in the org.netbeans package, but the compiler doesn’t know what that package is. I expect that the root cause is that a compile time project dependency is missing.

1. Whether IDE is the only problem?

Not really. The probably root cause is that your project is not configured correctly, and YOU have ignored the compilation errors that the IDE indicated to you when you previously built the project.

• The former can arises in different IDEs. Unless you configure the project dependencies correctly, the IDE cannot provide the correct classpath to the compiler.
• That latter is your fault, not the IDE’s fault. You shouldn’t ignore compilation errors.

There is not enough context in your Question to say where the actual error is. But you should be able to locate it by doing a clean and build of the package and looking at the compilation errors that it reports.

Answered By — Stephen C
Answer Checked By — Willingham (JavaFixing Volunteer)

public class AWTError extends Error

public AWTError(String msg)

OpenJDK

19

• Field Summary

• DstOut

• Class AWTEvent

• Class AWTEventMulticaster