[Java] Könnte mir jemand bei diesem Fehler helfen hab meinen code und die Fehlermeldung on

public int suchen(int oKontonummer){
 boolean suchenTaschentuch = false;
 int i=0;
 Fehlermeldung="Konto gefunden 1!"+i;
 while (suchenTaschentuch == false && i < meineKonten.length){
 if (meineKonten[i].getKontonummer()==oKontonummer){
 Fehlermeldung="Konto gefunden 2!"+i;
 suchenTaschentuch = true;
 }
 else{
 i++;
 }
 }
 if (suchenTaschentuch==false){
 Fehlermeldung = "Kontonummer nicht gefunden!";
 i= -1;
 }
 return i;
 }

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
 at Objektverwaltungsklasse.suchen(Objektverwaltungsklasse.java:120)
 at ObjektverwaltungsklasseGUI.KontonummeranzeigenButtonActionPerformed(ObjektverwaltungsklasseGUI.java:257)
 at ObjektverwaltungsklasseGUI$2.actionPerformed(ObjektverwaltungsklasseGUI.java:91)
 at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
 at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
 at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
 at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
 at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
 at java.awt.Component.processMouseEvent(Component.java:6038)
 at javax.swing.JComponent.processMouseEvent(JComponent.java:3260)
 at java.awt.Component.processEvent(Component.java:5803)
 at java.awt.Container.processEvent(Container.java:2058)
 at java.awt.Component.dispatchEventImpl(Component.java:4410)
 at java.awt.Container.dispatchEventImpl(Container.java:2116)
 at java.awt.Component.dispatchEvent(Component.java:4240)
 at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4322)
 at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3986)
 at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3916)
 at java.awt.Container.dispatchEventImpl(Container.java:2102)
 at java.awt.Window.dispatchEventImpl(Window.java:2429)
 at java.awt.Component.dispatchEvent(Component.java:4240)
 at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
 at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
 at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
 at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
 at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
 at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
 at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)