Run errors (is this due to arrays?)

Question

what possible errors could i have made with my arrays?
java.lang.NullPointerException
        at MRoom.doRecordArrays(MRoom.java:127)
        at MRoom.actionPerformed(MRoom.java:98)
        at //i've seen what the above errors are about, though i don't know how to remedy it. but the rest down the list i don't know where to find them:
java.awt.Button.processActionEvent(Button.java:381)
        at java.awt.Button.processEvent(Button.java:350)
        at java.awt.Component.dispatchEventImpl(Component.java:3526)
        at java.awt.Component.dispatchEvent(Component.java:3367)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:445)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchTh
read.java:190)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThre
ad.java:144)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:130)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:98)

Answer 1

Thanks for pointing that out :)
i tried to trace through the methods(btw, is there a way to watch the methods? i used to take cobol-i know, that's obsolete, but, useful =P - and there's an add watch feature per step/method that lets you monitor the step by step process of your program), and i think i made an error in inserting a record into the array. I made a few modifications, but still i got the same error message. Anyway, you're right, it's hard to explain what i want in my code unless i put it(it's embarassing, that's why), so here goes a part of my code:
====
IN MY MROOM class
//in actionPerformed
          if (e.getSource() == buttSaveUpdate)
*null pointer exception*/doRecordArrays();
          if (e.getSource() == buttSaveCancel)
     public void doRmGen()
//               chckRmNum = new Checkbox("Room No. " + y);
               add(new Label("Room No. "+y+" :"));
               rmNumber=y;
               Choice chooseRmType = new Choice();
               chooseRmType.add("Taxi Room");
               chooseRmType.add("Garage Room");
               chooseRmType.add("Suite");
               add(chooseRmType);
               invalidate();
               validate();
               buttSubmitRmQty.removeActionListener(this);
               ++y;
     public void doRecordArrays()
               Room[] record = new Room[rmQty];
               int x, y;
               for (x=0;x!=rmQty;++x) //this is what i added, because initially i only used y, which i think is the error because it jumps the array, which should have started at zero, while my y variable started at one, so i thought that was the null value that was being passed to my array.BUT i got the same run error messages, so im stuck.
                    for(y=1;y!=rmQty;++y)
     /*null pointer exception*/record[y].setRmRate(rmRate);
                    record[x].setRmNum(y);
                    record[x].setRmType(rmType);
                    record[x].setRmRate(rmRate);
                    //record[x].setcustN
                    //room number, room type, room rate, room occupancy, and cust ID
                    add(new Label("Room No. "+y+" :" +record[y].getRmRate()));
IN MY ROOM CLASS
public class Room
     public static String TAXI = "Taxi Room";
     public static String GARAGE = "Garage Room";
     public static String SUITE = "Suite";
     private static int rmN=0, rmR=0, custN=0;
     private String rmT=TAXI;
     boolean rmO=false;
     //room number, room type, room rate, room occupancy, and cust ID
     public Room(int a, String b, int c, boolean d, int cust)
          rmN = a;
          rmT = b;
          rmR = c;
          rmO = d;
          custN = cust;
     public int getRmNum()
          return rmN;
     public String getRmType()
          return rmT;
     public int getRmRate()
          if(rmT.equals(TAXI))
               rmR = MRoom.taxiRate;
          if(rmT.equals(GARAGE))
               rmR = MRoom.garageRate;
          if(rmT.equals(SUITE))
               rmR = MRoom.suiteRate;
          return rmR;
     public boolean getRmO()
          return rmO;
     public int getcustN()
          return custN;
     public void setRmNum(int rn)
          rmN = rn;
     public void setRmType(String rt)
          rmT = rt;
     public void setRmRate(int rr)
          rmR = rr;
     public void setRmO(boolean ro)
          rmO = ro;
     public void setcustN(int cn)
          custN = cn;
}public class Room
     public static String TAXI = "Taxi Room";
     public static String GARAGE = "Garage Room";
     public static String SUITE = "Suite";
     private static int rmN=0, rmR=0, custN=0;
     private String rmT=TAXI;
     boolean rmO=false;
     //room number, room type, room rate, room occupancy, and cust ID
     public Room(int a, String b, int c, boolean d, int cust)
          rmN = a;
          rmT = b;
          rmR = c;
          rmO = d;
          custN = cust;
     public int getRmNum()
          return rmN;
     public String getRmType()
          return rmT;
     public int getRmRate()
          if(rmT.equals(TAXI))
               rmR = MRoom.taxiRate;
          if(rmT.equals(GARAGE))
               rmR = MRoom.garageRate;
          if(rmT.equals(SUITE))
               rmR = MRoom.suiteRate;
          return rmR;
     public boolean getRmO()
          return rmO;
     public int getcustN()
          return custN;
     public void setRmNum(int rn)
          rmN = rn;
     public void setRmType(String rt)
          rmT = rt;
     public void setRmRate(int rr)
          rmR = rr;
     public void setRmO(boolean ro)
          rmO = ro;
     public void setcustN(int cn)
          custN = cn;
However...a null object was passed to the
doRecordArrays, or some null object was called from
that method...
The rest is a trace backward based on who called the
methods..
(actionPerformed called doRecordArrays, Button called
actionPerformed, and so on down the line).
The important line is line 1 &| 2
~Dave