Part 7

src/main/java/MapFunc/MapFunc.java

@@ -9,4 +9,19 @@ import java.util.function.Function;
  */
 public class MapFunc {
 
+    public static <T,R> ArrayList map(ArrayList<T> arrayList, Function<T,R> function) {
+
+        ArrayList<T> newArrayList = new ArrayList<>();
+
+        for (int i = 0; i < arrayList.size(); i++) {
+            newArrayList.add((T) function.apply(arrayList.get(i)));  //function.apply using the lambda
+        }
+        return newArrayList;
+    }
 }
+
+
+//MapFunc -- Make a map method that takes an ArrayList and a Function<T,R> object and
+//        returns an arraylist containing all of the elements of the first with the function applied to them.
+// T = type
+// R = return type

src/test/java/MapFunc/MapFuncTest.java

@@ -1,36 +1,36 @@
-//package MapFunc;
-//
-//import MapFunc.MapFunc;
-//import org.junit.Test;
-//
-//import java.util.ArrayList;
-//import org.junit.Assert;
-//
-//public class MapFuncTest {
-//    @Test
-//    public void testSingleTypeMap() throws Exception {
-//        // Given an integer array list
-//        ArrayList<Integer> intList = new ArrayList<>();
-//        intList.add(1);
-//        intList.add(2);
-//        // When it's mapped with a function to double the value
-//        ArrayList<Integer> mappedList = MapFunc.map(intList, num -> num*2);
-//        // Then all the values are doubled
-//        Assert.assertEquals(new Integer(2), mappedList.get(0));
-//        Assert.assertEquals(new Integer(4), mappedList.get(1));
-//    }
-//
-//    @Test
-//    public void testMultipleTypeMap() throws Exception {
-//        // Given an integer array list
-//        ArrayList<Integer> intList = new ArrayList<>();
-//        intList.add(1);
-//        intList.add(2);
-//        // When it's mapped with to string
-//        ArrayList<String> mappedList = MapFunc.map(intList, num -> num.toString());
-//        // Then all the values are doubled
-//        Assert.assertEquals("1", mappedList.get(0));
-//        Assert.assertEquals("2", mappedList.get(1));
-//    }
-//
-//}
+package MapFunc;
+
+import MapFunc.MapFunc;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import org.junit.Assert;
+
+public class MapFuncTest {
+    @Test
+    public void testSingleTypeMap() throws Exception {
+        // Given an integer array list
+        ArrayList<Integer> intList = new ArrayList<>();
+        intList.add(1);
+        intList.add(2);
+        // When it's mapped with a function to double the value
+        ArrayList<Integer> mappedList = MapFunc.map(intList, num -> num*2);
+        // Then all the values are doubled
+        Assert.assertEquals(new Integer(2), mappedList.get(0));
+        Assert.assertEquals(new Integer(4), mappedList.get(1));
+    }
+
+    @Test
+    public void testMultipleTypeMap() throws Exception {
+        // Given an integer array list
+        ArrayList<Integer> intList = new ArrayList<>();
+        intList.add(1);
+        intList.add(2);
+        // When it's mapped with to string
+        ArrayList<String> mappedList = MapFunc.map(intList, num -> num.toString());
+        // Then all the values are doubled
+        Assert.assertEquals("1", mappedList.get(0));
+        Assert.assertEquals("2", mappedList.get(1));
+    }
+
+}