Public int move(CDRack anotherRack)

Question

I have problems with method: move(CDRack anotherRack).
It removes CDs from anotherRack, but the rack I'm trying to fill in with anotherRack's CDs is filled with a one same CD from the anotherRack not various CDs as it should.. hard to explain.:)
Is some willing to give me tips? And is there some other way
to use insert method with the help of the move-method?
/**Class CDRack represents collections of compact discs. Discs are
located in the rack in slots numbered from zero upwards.The discs are
represented by Record objects and empty slots by null values. */
public class CDRack extends Object { 
  private Record[] collection;
/**Creates a new, empty CD rack. Parameters:size - the size of the new
rack, i.e. the number of slots it has */
    public CDRack(int size) {
       collection = new Record[size];   
       this.size = size;
/**Inserts a cd in the given rack slot if the slot in question is
empty. Parameters: disc - the cd to be added in the rackslot - the
number of a (hopefully empty) slot
Returns: a boolean value indicating if the insertion was successful.
    public boolean insert(Record disc, int slot) { 
       if (collection[slot]==null)) {    
         collection[slot] = record;    
         return true; 
       else return false; 
/** Inserts the given cd in the first empty rack slot (if there is even
one empty slot in the rack).
Parameters: disc - the disc to be added in the rack
Returns:
the number of the slot where the disc was added, or a negative number
if the rack was already full */
    public int insert(Record disc) {
       for(slot=0; slot<collection.length; slot++) {
         if(collection[slot]==null) {
            collection[slot] = disc;
            return slot;
       return -1; //not enough place
/** Moves all the discs from the given cd rack to this rack. The cds
from the other rack are inserted in the empty slots of this rack (in
ascending numerical order of slot numbers) in the order in which they
are located in the other rack. The moved discs are removed from their
original rack. Even if there is not enough space for all the discs in
this rack, as many cds are moved as possible.
Parameters:
anotherRack - another rack whose cds are to be moved into this one
Returns:
the number of cds moved from the other rack to this one */
    public int move(CDRack anotherRack) {
       int howMuchPlace = this.getSize() - this.getNumberOfCDs();
         if(anotherRack.getNumberOfCDs() <= howMuchPlace) {
            for(int i=0; i<anotherRack.getNumberOfCDs()+1; i++) {
              this.insert(disc);
            for(slot=0; slot<anotherRack.getNumberOfCDs()+1; i++) {
              anotherRack.remove(slot);
            return anotherRack.getNumberOfCDs();
        if(anotherRack.getNumberOfCDs() > howMuchPlace) {
            for(int i=0; i<howMuchPlace+1; i++) {
              this.insert(disc);
            for(slot=0; slot<howMuchPlace+1; i++) {
              anotherRack.remove(slot);
            return howMuchPlace;
         return -1;

Answer 1

I'm about to leave the office (it's 7PM in London and
there at least a dozen beers with my name on them ;)
but I'll take a look on Monday and see how you got
on.Sheesh. Must be Christmas or something :)
You still need to implement organize() and sortAlphabetically(), plus move the classes to their own files and modify the parameter names to match the assignment.
But, apart form that, here's what you wanted.
Now, I realy am going to ge those beers...
public class Maria2
     static class Record {}
     static class CDRack
          private Record[] mRecords;
          CDRack(int size) { mRecords= new Record[size]; }
          int find(Record disk)
               for (int i= 0; i < mRecords.length; i++) {
                    if (mRecords.equals(disk))
                         return i;
               return -1;
          Record getCD(int index)
               if (index < 0 || index >= mRecords.length)
                    return null;
               return mRecords[index];
          int getNumberOfCDs() { return getSize() -available(); }
          int getSize() { return mRecords.length; }
          int insert(Record record)
               int index= 0;
               for (; index < mRecords.length && mRecords[index] != null; index++);
               if (insert(record, index))
                    return index;
               return -1;
          boolean insert(Record record, int index)
               if (index >= mRecords.length)
                    return false;
               if (mRecords[index] != null)
                    return false;
               mRecords[index]= record;
               return true;
          private int available()
               int available= 0;
               for (int i= 0; i < mRecords.length; i++) {
                    if (mRecords[i] == null )
                         available++;
               return available;
          Record remove(int index)
               Record record= getCD(index);
               mRecords[index]= null;
               return record;
          int move(CDRack source)
               int moved= 0;
               for (int i= 0; i< source.getSize(); i++) {
                    Record record= source.getCD(i);
                    if (record == null)
                         continue;
                    if (insert(record) < 0)
                         break;
                    source.remove(i);
                    moved++;
               return moved;
     public static void main(String[] argv)
          CDRack rack1= new CDRack(32);
          CDRack rack2= new CDRack(18);
          for (int i= 0; i< rack1.getSize()/2; i++)
               rack1.insert(new Record(), i*2);
          for (int i= 0; i< rack2.getSize(); i++)
               rack2.insert(new Record(), i);
          System.err.println("Rack one has " rack1.getNumberOfCDs() " records");
          System.err.println("Rack two has " rack2.getNumberOfCDs() " records");
          int moved= rack1.move(rack2);
          System.err.println(moved +" records were moved");
          System.err.println("Rack one has " rack1.getNumberOfCDs() " records");
          System.err.println("Rack two has " rack2.getNumberOfCDs() " records");