Fix unused variable warnings

src/com/codefortomorrow/beginner/chapter2/examples/Variables.java

@@ -2,6 +2,7 @@
 
 public class Variables {
 
+    @SuppressWarnings("unused")
     public static void main(String[] args) {
         String name; // declaration
         name = "Kaz"; // initialization

src/com/codefortomorrow/beginner/chapter3/practice/FirstHalf.java

@@ -14,6 +14,7 @@
 
 public class FirstHalf {
 
+    @SuppressWarnings("unused")
     public static void main(String[] args) {
         String str1 = "WooHoo"; // should print "Woo"
         String str2 = "HelloThere"; // should print "Hello"

src/com/codefortomorrow/beginner/chapter3/practice/WithoutEnd.java

@@ -15,6 +15,7 @@
 
 public class WithoutEnd {
 
+    @SuppressWarnings("unused")
     public static void main(String[] args) {
         String str1 = "Hello"; // should print "ell"
         String str2 = "java"; // should print "av"

src/com/codefortomorrow/beginner/chapter3/solutions/Initialize.java

@@ -14,6 +14,7 @@
 
 public class Initialize {
 
+    @SuppressWarnings("unused")
     public static void main(String[] args) {
         boolean isRaining = false;
         double price = 5.68;

src/com/codefortomorrow/beginner/chapter4/examples/Arithmetic.java

@@ -4,21 +4,27 @@ public class Arithmetic {
 
     public static void main(String[] args) {
         // addition
-        int a = 5 + 1; // a has the value 6
+        int a = 5 + 1;
+        System.out.println("a is " + a);
 
         // subtraction
-        double b = 25.6 - 90; // b has the value 64.4
+        double b = 25.6 - 90;
+        System.out.println("b is " + b);
 
         // multiplication
-        int c = 12 * 4; // c has the value 48
+        int c = 12 * 4;
+        System.out.println("c is " + c);
 
         // integer division
-        int d = 10 / 3; // d has the value 3
+        int d = 10 / 3;
+        System.out.println("d is " + d);
 
         // double division
-        double e = 10.0 / 3; // e has the value 3.3333333...
+        double e = 10.0 / 3;
+        System.out.println("e is " + e);
 
         // modulus
-        int f = 10 % 3; // f has the value 1
+        int f = 10 % 3;
+        System.out.println("f is " + f);
     }
 }

src/com/codefortomorrow/beginner/chapter4/examples/AugmentedAssignment.java

@@ -3,12 +3,23 @@
 public class AugmentedAssignment {
 
     public static void main(String[] args) {
-        int a = 1;
+        int a = 10;
+        System.out.println("1. a is " + a);
 
         a += 1; // equivalent to a = a + 1;
+        System.out.println("2. a is " + a);
+
         a -= 2; // equivalent to a = a - 2;
+        System.out.println("3. a is " + a);
+
         a *= 3; // equivalent to a = a * 3;
+        System.out.println("4. a is " + a);
+
+        // NOTE: In this case, we are doing integer division
         a /= 4; // equivalent to a = a / 4;
+        System.out.println("5. a is " + a);
+
         a %= 5; // equivalent to a = a % 5;
+        System.out.println("6. a is " + a);
     }
 }

src/com/codefortomorrow/beginner/chapter9/examples/InitializeArray.java

@@ -2,6 +2,7 @@
 
 public class InitializeArray {
 
+    @SuppressWarnings("unused")
     public static void main(String[] args) {
         // declare an array - can be initialized later
         // with either of the initialization methods below

src/com/codefortomorrow/intermediate/chapter12/examples/WrapperClasses.java

@@ -2,6 +2,7 @@
 
 public class WrapperClasses {
 
+    @SuppressWarnings("unused")
     public static void main(String[] args) {
         // auto-boxing (int to Integer)
         Integer intObject = 2;

src/com/codefortomorrow/intermediate/chapter12/practice/Account.java

@@ -4,6 +4,7 @@
 Create a UML diagram for the Account class.
  */
 
+@SuppressWarnings("unused")
 public class Account {
 
     private String name;