Java GUI nicht öffnen ... läuft im Hintergrund statt ... andere Antworten funktionieren nicht

Question

Jedes Mal, wenn ich mein Programm ausführen, zeigt es immer eine NullPointerException, wenn keine meiner Variablen als null deklariert sind ... irgendwelche Ideen warum ?

public void BrownTank() { 
     while (true) { 
      int speed = 2; 
      Random randomGenerator = new Random(); 
      int Movement = randomGenerator.nextInt(4) + 1; 
      if (Movement == 1) { 
       jLabel2.setBounds(jLabel2.getX(), jLabel2.getY() - speed, jLabel2.getWidth(), jLabel2.getHeight()); 
      } 

      if (Movement == 2) { 
       jLabel2.setBounds(jLabel2.getX(), jLabel2.getY() + speed, jLabel2.getWidth(), jLabel2.getHeight()); 
      } 

      if (Movement == 3) { 
       jLabel2.setBounds(jLabel2.getX() - speed, jLabel2.getY(), jLabel2.getWidth(), jLabel2.getHeight()); 
      } 

      if (Movement == 4) { 
       jLabel2.setBounds(jLabel2.getX() + speed, jLabel2.getY(), jLabel2.getWidth(), jLabel2.getHeight()); 
      } 
     } 
    } 

EDIT: Dies ist der vollständige Code

package tanks; 

import java.util.Random; 

public class Tanks extends javax.swing.JFrame { 

    public Tanks() { 
     BrownTank(); 
     initComponents(); 
    } 

    @SuppressWarnings("unchecked") 
    // <editor-fold defaultstate="collapsed" desc="Generated Code">       
    private void initComponents() { 

     jLabel1 = new javax.swing.JLabel(); 
     jLabel2 = new javax.swing.JLabel(); 

     setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); 
     setTitle("Tanks!"); 
     addKeyListener(new java.awt.event.KeyAdapter() { 
      public void keyPressed(java.awt.event.KeyEvent evt) { 
       formKeyPressed(evt); 
      } 
     }); 

     jLabel1.setFont(new java.awt.Font("PMingLiU", 1, 16)); // NOI18N 
     jLabel1.setText("◻"); 

     jLabel2.setFont(new java.awt.Font("PMingLiU", 1, 18)); // NOI18N 
     jLabel2.setForeground(new java.awt.Color(102, 51, 0)); 
     jLabel2.setText("◻"); 

     javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane()); 
     getContentPane().setLayout(layout); 
     layout.setHorizontalGroup(
      layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
      .addGroup(layout.createSequentialGroup() 
       .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
        .addGroup(layout.createSequentialGroup() 
         .addGap(46, 46, 46) 
         .addComponent(jLabel2)) 
        .addGroup(layout.createSequentialGroup() 
         .addGap(244, 244, 244) 
         .addComponent(jLabel1))) 
       .addContainerGap(315, Short.MAX_VALUE)) 
     ); 
     layout.setVerticalGroup(
      layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
      .addGroup(layout.createSequentialGroup() 
       .addGap(24, 24, 24) 
       .addComponent(jLabel2) 
       .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 281, Short.MAX_VALUE) 
       .addComponent(jLabel1) 
       .addGap(89, 89, 89)) 
     ); 

     pack(); 
    }// </editor-fold>       

    private void formKeyPressed(java.awt.event.KeyEvent evt) {         
     int speed = 3; 
     if (evt.getKeyChar() == 'w') { 
      jLabel1.setBounds(jLabel1.getX(), jLabel1.getY() - speed, jLabel1.getWidth(), jLabel1.getHeight()); 
     } 
     if (evt.getKeyChar() == 's') { 
      jLabel1.setBounds(jLabel1.getX(), jLabel1.getY() + speed, jLabel1.getWidth(), jLabel1.getHeight()); 
     } 
     if (evt.getKeyChar() == 'a') { 
      jLabel1.setBounds(jLabel1.getX() - speed, jLabel1.getY(), jLabel1.getWidth(), jLabel1.getHeight()); 
     } 
     if (evt.getKeyChar() == 'd') { 
      jLabel1.setBounds(jLabel1.getX() + speed, jLabel1.getY(), jLabel1.getWidth(), jLabel1.getHeight()); 
     } 
    }        

    public void PlayerBullet() { 

    } 

    public void BrownTank() { 
     while (true) { 
      int speed = 2; 
      Random randomGenerator = new Random(); 
      int Movement = randomGenerator.nextInt(4) + 1; 
      if (Movement == 1) { 
       jLabel2.setBounds(jLabel2.getX(), jLabel2.getY() - speed, jLabel2.getWidth(), jLabel2.getHeight()); 
      } 

      if (Movement == 2) { 
       jLabel2.setBounds(jLabel2.getX(), jLabel2.getY() + speed, jLabel2.getWidth(), jLabel2.getHeight()); 
      } 

      if (Movement == 3) { 
       jLabel2.setBounds(jLabel2.getX() - speed, jLabel2.getY(), jLabel2.getWidth(), jLabel2.getHeight()); 
      } 

      if (Movement == 4) { 
       jLabel2.setBounds(jLabel2.getX() + speed, jLabel2.getY(), jLabel2.getWidth(), jLabel2.getHeight()); 
      } 
     } 
    } 

    public static void main(String args[]) { 

     java.awt.EventQueue.invokeLater(new Runnable() { 
      public void run() { 
       new Tanks().setVisible(true); 
      } 
     }); 
    } 

    // Variables declaration - do not modify      
    private javax.swing.JLabel jLabel1; 
    private javax.swing.JLabel jLabel2; 
    // End of variables declaration     
} 

mein Programm für die Antwort nach der Bearbeitung ... wenn ich versuche, es zu laufen, ist es nicht eine GUI und läuft öffnet in der Hintergrund.

Answer 1

Sie sollten Ihre jLabel2 init initialisieren.

Bevor Sie also BrownTank() anrufen, rufen Sie initComponents().