Fix grammar (#78)

* Fix grammar

* Fix grammar

* Fix grammar

* Fix grammar and code challenge

Author: zohairawan

src/boxed_primitives.md

@@ -24,7 +24,7 @@ void main() {
 }
 ```
 
-We call these primitives which might be null "Boxed Primitives" because you they are made by taking
+We call these primitives which might be null "Boxed Primitives" because they are made by taking
 the underlying thing and putting it in a "box."[^boxing]
 
 

src/boxed_primitives/boolean.md

@@ -8,5 +8,5 @@ The type to use for a `boolean` that might be null is `Boolean`.
 Boolean b = null;
 System.out.println(b);
 b = true;
-System.out.println(true);
+System.out.println(b);
 ~}

src/boxed_primitives/challenges.md

@@ -28,7 +28,7 @@ void main() {
 
 ## Challenge 2.
 
-Write a method which takes in a `Integer[]` representing
+Write a method which takes in an `Integer[]` representing
 a series of distances and prints out every distance
 followed by ` kilometers`.
 
@@ -50,7 +50,7 @@ void printDistances(Integer[] distances) {
 }
 
 void main() {
-    printNames(new String[] {
+    printDistances(new Integer[] {
         45,
         99,
         23

src/boxed_primitives/character.md

@@ -11,7 +11,7 @@ System.out.println(c);
 ~}
 ```
 
-Unlike a `char[]`, a `Character[]` will not be have its contents
+Unlike a `char[]`, a `Character[]` will not have its contents
 shown when printed.
 
 ```java