Complete extension exercises

Author: pudkipz

src/main/java/com/booleanuk/extension/Extension.java

@@ -29,7 +29,7 @@ public StringBuilder one() {
         // 1. Using the sb variable above, add "Hello, world!" to the StringBuilder
         // WRITE YOUR CODE BETWEEN THIS LINE...
 
-
+        sb.append("Hello, world!");
 
         // ...AND THIS LINE
 
@@ -43,7 +43,8 @@ public StringBuilder two() {
         // 2. After adding the message, use an appropriate StringBuilder method to reverse it
         // WRITE YOUR CODE BETWEEN THIS LINE...
 
-
+        sb.append("Hello, world!");
+        sb.reverse();
 
         // ...AND THIS LINE
 
@@ -57,7 +58,8 @@ public StringBuilder three() {
         // 2. After adding the message, remove the comma.
         // WRITE YOUR CODE BETWEEN THIS LINE...
 
-
+        sb.append("Hello, world!");
+        sb.deleteCharAt(5);
 
         // ...AND THIS LINE
 
@@ -71,7 +73,8 @@ public StringBuilder four() {
         // 2. After adding the message, replace the word "world" with the word "Java"
         // WRITE YOUR CODE BETWEEN THIS LINE...
 
-
+        sb.append("Hello, world!");
+        sb.replace(7, 12, "Java");
 
         // ...AND THIS LINE