Stupid NPE, passing over RMI, it is externalizable.

Question

Hi,
I have an object (ObjectA) which holds a 2 element array of objects (ObjectB). Both objects are externalizable and have the read/writeExternal methods implemented. However when the server side receives the object the array of objects (ObjectB) contains all null values. Anyone any ideas?
Thanks

Answer 1

The null pointer exception occurs when I try to access a string in ObjectB. Its actually a 4 element array also. (Dont ask!).
Code:
        //This is in the writeExternal
        if (objectBInstance!= null && objectBInstance.length > 0) {
              oo.writeInt(objectBInstance.length);
              oo.writeInt(objectBInstance[0].length);
              oo.writeInt(objectBInstance[0][0].length);
              oo.writeInt(objectBInstance[0][0][0].length);
              for (int i = 0; i < objectBInstance.length; i++) {
                   for (int j = 0; j < objectBInstance.length; j++) {
                    for (int k = 0; k < objectBInstance[i][j].length; k++) {
                         for (int l = 0; l < objectBInstance[i][j][k].length; l++) {
                              oo.writeObject(objectBInstance[i][j][k][l]);
     } else {
          oo.writeInt(0);
//This is in the readExternal
length = oi.readInt();
     if (length > 0) {
     int length2 = oi.readInt();
int length3 = oi.readInt();
int length4 = oi.readInt();
          objectBInstance= new ObjectB[length][length2][length3][length4];
          for (int i = 0; i < length; i++) {
               for (int j = 0; j < length2; j++) {
                    for (int k = 0; k < length3; k++) {
                         for (int l = 0; l < length4; l++) {
                              objectBInstance[i][j][k][l] = new ObjectB();
                              objectBInstance[i][j][k][l] = (ObjectB)oi.readObject();
Messy i know!
The read/writeExternal in the objects used in ObjectB are ok too.