ch06 revisions

Author: ChrisMayfield

ch06/Loops.java

@@ -1,5 +1,5 @@
 /**
- * Examples from Chapter 6.
+ * Demonstrates uses of loops.
  */
 public class Loops {
 
@@ -26,15 +26,22 @@ public static void plusplus() {
         int i = 1;
         while (i <= 5) {
             System.out.println(i);
-            i++; // add 1 to i
+            i++;  // add 1 to i
         }
     }
 
     public static void appreciate() {
         int i = 2;
         while (i <= 8) {
             System.out.print(i + ", ");
-            i += 2; // add 2 to i
+            i += 2;  // add 2 to i
+        }
+        System.out.println("Who do we appreciate?");
+    }
+
+    public static void appreciate2() {
+        for (int i = 2; i <= 8; i += 2) {
+            System.out.print(i + ", ");
         }
         System.out.println("Who do we appreciate?");
     }
@@ -57,22 +64,25 @@ public static void nested() {
     }
 
     public static void main(String[] args) {
-        System.out.println("countdown");
+        System.out.println("\ncountdown");
         countdown(3);
 
-        System.out.println("sequence");
+        System.out.println("\nsequence");
         sequence(10);
 
-        System.out.println("plusplus");
+        System.out.println("\nplusplus");
         plusplus();
 
-        System.out.println("appreciate");
+        System.out.println("\nappreciate");
         appreciate();
 
-        System.out.println("loopvar");
+        System.out.println("\nappreciate2");
+        appreciate2();
+
+        System.out.println("\nloopvar");
         loopvar();
 
-        System.out.println("nested");
+        System.out.println("\nnested");
         nested();
     }
 

ch06/Strings.java

@@ -1,5 +1,7 @@
+import java.util.Scanner;
+
 /**
- * Demonstrates uses of Strings.
+ * Demonstrates uses of strings.
  */
 public class Strings {
 
@@ -10,8 +12,8 @@ public static void main(String[] args) {
         String fruit = "banana";
         char letter0 = fruit.charAt(0);
 
-        if (letter0 == 'a') {
-            System.out.println('?');
+        if (letter0 == 'A') {
+            System.out.println("It's an A!");
         }
 
         System.out.print("Roman alphabet: ");
@@ -26,6 +28,17 @@ public static void main(String[] args) {
         }
         System.out.println();
 
+        // Which loop to use
+
+        Scanner in = new Scanner(System.in);
+        System.out.print("Enter a number: ");
+        while (!in.hasNextDouble()) {
+            String word = in.next();
+            System.err.println(word + " is not a number");
+            System.out.print("Enter a number: ");
+        }
+        double number = in.nextDouble();
+
         // String iteration
 
         for (int i = 0; i < fruit.length(); i++) {
@@ -43,33 +56,44 @@ public static void main(String[] args) {
         int index = fruit.indexOf('a');
         int index2 = fruit.indexOf('a', 2);
 
+        // Substrings
+
+        System.out.println(fruit.substring(0, 3));
+        System.out.println(fruit.substring(2, 5));
+        System.out.println(fruit.substring(6, 6));
+
+        System.out.println(fruit.substring(0));
+        System.out.println(fruit.substring(2));
+        System.out.println(fruit.substring(6));
+
         // String comparison
 
+        System.out.print("Play again? ");
+        String answer = in.nextLine();
+        if (answer == "yes") {                 // wrong!
+            System.out.println("Let's go!");
+        } else {
+            System.out.println("Goodbye!");
+        }
+        
+        if (answer.equals("yes")) {            // correct
+            System.out.println("Let's go!");
+        }
+
         String name1 = "Alan Turing";
         String name2 = "Ada Lovelace";
         if (name1.equals(name2)) {
             System.out.println("The names are the same.");
         }
 
         int diff = name1.compareTo(name2);
-        if (diff == 0) {
-            System.out.println("The names are the same.");
-        } else if (diff < 0) {
+        if (diff < 0) {
             System.out.println("name1 comes before name2.");
         } else if (diff > 0) {
             System.out.println("name2 comes before name1.");
+        } else {
+            System.out.println("The names are the same.");
         }
-
-        // Substrings
-
-        System.out.println(fruit.substring(0));
-        System.out.println(fruit.substring(2));
-        System.out.println(fruit.substring(6));
-
-        System.out.println(fruit.substring(0, 3));
-        System.out.println(fruit.substring(2, 5));
-        System.out.println(fruit.substring(6, 6));
-
     }
 
     /**