public String preOrder(int nodeIndex) {
if(nodeIndex>nodeArray.length) {
return(null);
} else if(nodeArray[nodeIndex].isLeaf(nodeArray.length-1)) {
return(nodeArray[nodeIndex].toString());
} else {
return(nodeArray[nodeIndex].toString()+" "+preOrder(nodeArray[nodeIndex].leftChild)+" "+preOrder(nodeArray[nodeIndex].rightChild));
}

I am really stack with it. I dont how to output the numbers i input. If i input: 1 2 3 4 5 6, it only outputs 1 2 3. Please help me, I really need your help. Thank you in advance. We have to use arrays.
}

what you have there doesn't explain a whole lot...