I have this piece of code: public lot merge (lot otherlot){ wafer[] mWaferarray = new wafer[16]; byte[] bytearray = new byte[16]; wafer resultwafer = new wafer(bytearray); wafer w1; wafer w2; int i; int[][] assignmentmatrix = HungarianAlgorithm.computeAssignments(convertinttofloat (solutionmatrix(otherlot))); for (i=0; i != assignmentmatrix.length ;i++){ w1 = otherlot.getWaferarray()[assignmentmatrix[i][0]]; w2 = getWaferarray()[assignmentmatrix[i][1]]; resultwafer.setWafer(w1.wafercompare(w2)); mWaferarray[i] = resultwafer; mWaferarray[i].print(); } System.out.println("HERE\n"); mWaferarray[5].toString(); resultlot = new lot(mWaferarray); resultlot.print();// Problem occurs here. return resultlot; } As you can see I create an array of wafers (selfdefined class). Then I fill this up with new wafers. When I print this array (mWaferarray[i].print()) it gives me the wanted results. But when I go out of the "for"-loop the array is broken and it is as if the last item I add to mWaferarray fills it up (the entire array, 16 long, is filled with this wafer). So if run this program this is what I get: 1011110010111100 0011011111111110 0111110111101101 1010111001101111 0110110111101111 1010110101111010 1010110111011110 1011111010111100 1111110011101110 0111111111011011 1111111111011010 1101111011111010 1010110101011110 0101111011011010 1011111011011000 0101111011011010 HERE 0101111011011010 0101111011011010 0101111011011010 0101111011011010 0101111011011010 0101111011011010 0101111011011010 0101111011011010 0101111011011010 0101111011011010 0101111011011010 0101111011011010 0101111011011010 0101111011011010 0101111011011010 0101111011011010 As you can see it is as if the array is filled with the last wafer. I have been looking at this for some time now, I hope you guy can help me out. Thx in advance PS: my print functions are written like this: void print(){ int j; for (j=0; j != waferarray.length ;j++){ waferarray[j].print(); } } EDIT: added code for lot this is the beginning of the lot class public class lot { wafer[] waferarray = new wafer[16]; lot resultlot; public lot (wafer wafer1,wafer wafer2,wafer wafer3,wafer wafer4, wafer wafer5,wafer wafer6,wafer wafer7,wafer wafer8, wafer wafer9,wafer wafer10,wafer wafer11,wafer wafer12, wafer wafer13,wafer wafer14,wafer wafer15,wafer wafer16){ waferarray[0] = wafer1; waferarray[1] = wafer2; waferarray[2] = wafer3; waferarray[3] = wafer4; waferarray[4] = wafer5; waferarray[5] = wafer6; waferarray[6] = wafer7; waferarray[7] = wafer8; waferarray[8] = wafer9; waferarray[9] = wafer10; waferarray[10] = wafer11; waferarray[11] = wafer12; waferarray[12] = wafer13; waferarray[13] = wafer14; waferarray[14] = wafer15; waferarray[15] = wafer16; } public lot (wafer[] thiswaferarray){ waferarray = thiswaferarray; }