I'm learning about linked-list in Java and trying to make an function to add new point into Linked- List with given index. please help me review my code then tell me what I'm doing wrong here. Thank you so much in advance!!!.
My program has 2 class name Waypoint and TourElement. I also have some test cases.
Waypoint
public class Waypoint {
int x;
int y;
public int getX() {
return this.x;
}
public int getY() {
return this.y;
}
public void setXY(int x, int y) {
this.x = x;
this.y = y;
}
int[] toArray() {
int array[] = new int[2];
array[0] = getX();
array[1] = getY();
return array;
}
@Override
public String toString() {
String convertToString = "(" + getX() + "/" + getY() + ")";
return convertToString;
}
TourElement
public class TourElement {
private Waypoint points;
private TourElement next;
public void setWaypoint( Waypoint points) {
this.points = points;
}
public void setNext(TourElement next) {
this.next = next;
}
Waypoint getWaypoint() {
return this.points;
}
TourElement getNext() {
return this.next;
}
boolean hasNext() {
if(this.next != null) {
return true;
}
return false;
}
int getNoOfWaypoints() {// return the number of waypoints in the list
int count = 1;
TourElement current = this;
while(current.next != null) {
count++;
current = current.next;
System.out.println(count);
}
return count;
}
Here is function to insert new point with given index:
TourElement insertAt(int index, Waypoint waypoint) {
int lengthLinkList = getNoOfWaypoints();
TourElement current = this;
int count = 0;
if(waypoint == null || index < 0 || index > lengthLinkList) {
return this;
} else {
if(index == 0) {
TourElement newElement = new TourElement();
newElement.setWaypoint(waypoint);
newElement.setNext(this);
return newElement;
} else {
while(current.next != null) { //I think I'm doing wrong here when trying to add new points.
if(index == count) {
TourElement newElement = new TourElement();
current.setNext(current);
newElement.setWaypoint(waypoint);
newElement.setNext(current.next);
return newElement;
}
count++;
current = current.next;
}
if(current.next == null) {
TourElement newElement = new TourElement();
current.setNext(newElement);
newElement.setWaypoint(waypoint);
newElement.setNext(null);
}
}
return this;
}
}
Here is my test case: //Create Element List:
private Waypoint createWaypoint(int x, int y) {
Waypoint wp = new Waypoint();
wp.setXY(x, y);
return wp;
}
/**
* Creates a ElementList with the given waypoints.
* @param waypoints array of waypoints to use, the coordinates of the waypoints are also in an array
* @return List of elements with the given waypoints
* @pre at least one waypoint has to be in array
*/
private TourElement createElementList(int[][] waypoints){
assert waypoints.length > 0;
TourElement elem = new TourElement();
int lastIndex = waypoints.length-1;
Waypoint wp = createWaypoint(waypoints[lastIndex][0], waypoints[lastIndex][1]);
elem.setWaypoint(wp);
for (int i = lastIndex-1; i >= 0 ; i--) {
wp = createWaypoint(waypoints[i][0], waypoints[i][1]);
elem = elem.addStart(wp);
}
return elem;
}
Test case 1: Passed
@Test
public void testInsertAt_BeforeFirst() {
TourElement elem = createElementList(new int[][] {{1, 1}, {3, 3}});
Waypoint wp = createWaypoint(0, 0);
elem = elem.insertAt(0, wp);
assertArrayEquals(new int[] {0, 0}, elem.getWaypoint().toArray());
assertArrayEquals(new int[] {1, 1}, elem.getNext().getWaypoint().toArray());
assertArrayEquals(new int[] {3, 3}, elem.getNext().getNext().getWaypoint().toArray());
assertNull(elem.getNext().getNext().getNext());
}
Test cases 2: Failed
The error is: array first differed at element[0]; expect <2> but was:<3>
@Test
public void testInsertAt_Second() {
TourElement elem = createElementList(new int[][] {{1, 1}, {3, 3}});
Waypoint wp = createWaypoint(2, 2);
elem = elem.insertAt(1, wp);
assertArrayEquals(new int[] {1, 1}, elem.getWaypoint().toArray());
assertArrayEquals(new int[] {2, 2}, elem.getNext().getWaypoint().toArray());
assertArrayEquals(new int[] {3, 3}, elem.getNext().getNext().getWaypoint().toArray());
assertNull(elem.getNext().getNext().getNext());
}
Test case 3: passed
@Test
public void testInsertAt_Last() {
TourElement elem = createElementList(new int[][] {{1, 1}, {3, 3}});
Waypoint wp = createWaypoint(4, 4);
elem = elem.insertAt(2, wp);
assertArrayEquals(new int[] {1, 1}, elem.getWaypoint().toArray());
assertArrayEquals(new int[] {3, 3}, elem.getNext().getWaypoint().toArray());
assertArrayEquals(new int[] {4, 4}, elem.getNext().getNext().getWaypoint().toArray());
assertNull(elem.getNext().getNext().getNext());
}
In the function insertAt(index, waypoint), this function passed when index = 0 or index = last. But I don't understand why second test case doesn't pass.
Please help me!!
createElementList()because you are using its return value to do the insert