Interface doesn't allow for variable declarations

src/CheckersGameState3.java

@@ -182,7 +182,7 @@ private void generate_moves(int origin, int delta1, int delta2, List<Move> moves
     }
 
 
-    private void calculate_jumps(String path, int[] b, int orig, int delta1, int delta2, List<Move3> jumps, boolean king){
+    private void calculate_jumps(String path, int[] b, int orig, int delta1, int delta2, List<Move> jumps, boolean king){
         if(!any_jumps(orig, delta1, delta2, b, king)){
             if(path.contains(",")){
                 jumps.add(new Move3(path));
@@ -226,16 +226,16 @@ private void calculate_jumps(String path, int[] b, int orig, int delta1, int del
 
     CheckersGameState3 result(Move x){
         int[] newState = this.board.clone();
-        newState[x.destination()] = this.board[x.origin()];
-        newState[x.origin()] = 0;
-        if(x.destination < 4 &&  this.player == 2){
+        newState[x.destination()] = this.board[x.source()];
+        newState[x.source()] = 0;
+        if(x.destination() < 4 &&  this.player == 2){
             newState[x.destination()] = 4;
         }
         else if(x.destination() > 30 && this.player == 1){
            newState[x.destination()] = 3;
         }
-        if(x.kills() != null){
-            for(int k: x.kills()){
+        if(x.captures() != null){
+            for(int k: x.captures()){
                 newState[k] = 0;
             }
         }

src/Move.java

@@ -1,6 +1,7 @@
 
 public interface Move {
-  // Starting and ending Positions
+  public int source();
+  public int destination();
   // Returns a list of captured positions
   public int[] captures();
   // Returns the string representation of a move

src/Move3.java

@@ -25,7 +25,7 @@ public int[] calculate_kills(String[] steps){
         return k;
     }
 
-    public int origin(){
+    public int source(){
         return src;
     }
 

src/Test.java

@@ -22,7 +22,8 @@ public static void main(String[] args){
 
         CheckersGameState3 s2 = new CheckersGameState3(1, b2);
         s2.printState();
-        for(Move3 m: s2.actions()){
+        s2.result(s2.actions().get(1)).printState();
+        for(Move m: s2.actions()){
             System.out.println(m);
         }
     }