ch10 revisions

ChrisMayfield · ChrisMayfield · commit fbd0dca5e78e · 2020-06-17T16:15:28.000-04:00
diff --git a/ch10/Append.java b/ch10/Append.java
diff --git a/ch10/Builder.java b/ch10/Builder.java
@@ -0,0 +1,35 @@
+import java.util.Scanner;
+
+/*
+ * StringBuilder example.
+ */
+public class Builder {
+
+    public static void main(String[] args) {
+        Scanner in = new Scanner(System.in);
+
+        // less efficient
+        System.out.println("Enter 10 lines:");
+        
+        String slow = "";
+        for (int i = 0; i < 10; i++) {
+            String line = in.nextLine();        // new string
+            slow = slow + line + '\n';    // two more strings
+        }
+        System.out.print("You entered:\n" + slow);
+
+        // more efficient
+        System.out.println("Enter 10 lines:");
+
+        StringBuilder text = new StringBuilder();
+        for (int i = 0; i < 10; i++) {
+            String line = in.nextLine();
+            text.append(line);
+            text.append('\n');
+        }
+        System.out.print("You entered:\n" + text);
+        
+        String result = text.toString();
+    }
+
+}
diff --git a/ch10/PointRect.java b/ch10/PointRect.java
@@ -9,27 +9,40 @@ public class PointRect {
     public static void main(String[] args) {
         Point blank;
         blank = new Point(3, 4);
-        System.out.println(blank);
 
         int x = blank.x;
         System.out.println(blank.x + ", " + blank.y);
         int sum = blank.x * blank.x + blank.y * blank.y;
 
+        // objects as parameters
+
         Point p1 = new Point(0, 0);
         Point p2 = new Point(3, 4);
+        double temp = distance(p1, p2);
         double dist = p1.distance(p2);  // dist is 5.0
+        System.out.println(blank);
+
+        // objects as return values
 
         Rectangle box = new Rectangle(0, 0, 100, 200);
-        moveRect(box, 50, 100);
+        Point center = findCenter(box);
+
+        // rectangles are mutable
+
+        moveRect(box, 50, 100);  // now at (50, 100, 100, 200)
         System.out.println(box);
+
+        box = new Rectangle(0, 0, 100, 200);
         box.translate(50, 100);
 
+        // aliasing revisited
+
         Rectangle box1 = new Rectangle(0, 0, 100, 200);
         Rectangle box2 = box1;
 
-        System.out.println(box2.width);
         box1.grow(50, 50);
-        System.out.println(box2.width);
+        System.out.println(box1);
+        System.out.println(box2);
     }
 
     /**
