It fails one of the test cases idk why.
public void evenAfterOdd() throws Exception {
int index = 0;
Node node = this.head;
while(node!=null){
if(node.data%2==1){
int temp = node.data;
node.data = getNodeAt(index).data;
getNodeAt(index).data = temp;
index++;
}
node = node.next;
}
}