Substituted interface with one class

app/src/main/java/com/example/paktalin/agilejava_exercises/BlackSide.java

-package com.example.paktalin.agilejava_exercises;
-
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
-
-/**
- * Created by Paktalin on 26/05/2018.
- */
-
-class BlackSide implements Side {
-
-    private List<Piece> pieces = new ArrayList<>();
-
-    @Override
-    public List<Piece> getPieces() {
-        return pieces;
-    }
-
-    @Override
-    public double getStrength() {
-        double strength = 0.0;
-        for (Piece piece : pieces)
-            strength += piece.getStrength();
-        return strength;
-    }
-
-    @Override
-    public int getPiecesCount() {
-        return pieces.size();
-    }
-
-    @Override
-    public int getPiecesCount(Piece.Type type) {
-        int count = 0;
-
-        for (Piece piece : pieces)
-            if (piece.isType(type))
-                count++;
-
-        return count;
-    }
-
-    @Override
-    public void addPiece(Piece piece) {
-        pieces.add(piece);
-        Collections.sort(pieces);
-    }
-}

app/src/main/java/com/example/paktalin/agilejava_exercises/Board.java

@@ -15,8 +15,8 @@ class Board {
 
     private Piece[][] pieces = new Piece[ROW_COUNT][COLUMN_COUNT];
 
-    private WhiteSide whiteSide = new WhiteSide();
-    private BlackSide blackSide = new BlackSide();
+    private Side whiteSide = new Side();
+    private Side blackSide = new Side();
 
     private Board() {}
 

app/src/main/java/com/example/paktalin/agilejava_exercises/Side.java

 package com.example.paktalin.agilejava_exercises;
 
+import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 /**
- * Created by Paktalin on 26/05/2018.
+ * Created by Paktalin on 27/05/2018.
  */
 
-interface Side {
+class Side {
+    private List<Piece> pieces = new ArrayList<>();
 
-    List<Piece> getPieces();
-    double getStrength();
-    int getPiecesCount();
-    int getPiecesCount(Piece.Type type);
-    void addPiece(Piece piece);
+    public List<Piece> getPieces() {
+        return pieces;
+    }
+
+    public double getStrength() {
+        double strength = 0.0;
+        for (Piece piece : pieces)
+            strength += piece.getStrength();
+        return strength;
+    }
+
+    public int getPiecesCount() {
+        return pieces.size();
+    }
+
+    public int getPiecesCount(Piece.Type type) {
+        int count = 0;
+
+        for (Piece piece : pieces)
+            if (piece.isType(type))
+                count++;
+
+        return count;
+    }
+
+    public void addPiece(Piece piece) {
+        pieces.add(piece);
+        Collections.sort(pieces);
+    }
 }

app/src/main/java/com/example/paktalin/agilejava_exercises/WhiteSide.java

-package com.example.paktalin.agilejava_exercises;
-
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
-
-/**
- * Created by Paktalin on 26/05/2018.
- */
-
-public class WhiteSide implements Side {
-
-    private List<Piece> pieces = new ArrayList<>();
-
-    @Override
-    public List<Piece> getPieces() {
-        return pieces;
-    }
-
-    @Override
-    public double getStrength() {
-        double strength = 0.0;
-        for (Piece piece : pieces)
-            strength += piece.getStrength();
-        return strength;
-    }
-
-    @Override
-    public int getPiecesCount() {
-        return pieces.size();
-    }
-
-    @Override
-    public int getPiecesCount(Piece.Type type) {
-        int count = 0;
-
-        for (Piece piece : pieces)
-            if (piece.isType(type))
-                count++;
-
-        return count;
-    }
-
-    @Override
-    public void addPiece(Piece piece) {
-        pieces.add(piece);
-        Collections.sort(pieces);
-    }
-}