Fixed onjava/Range.java, added TestRange.java

Author: BruceEckel

concurrent/PSP2.txt

@@ -5,7 +5,7 @@
 4: main
 5: main
 6: main
+6: ForkJoinPool.commonPool-worker-9
 7: main
-8: main
+8: ForkJoinPool.commonPool-worker-9
 9: main
-10: ForkJoinPool.commonPool-worker-5

housekeeping/Overloading.java

@@ -32,7 +32,7 @@ public static void main(String[] args) {
       t.info();
       t.info("overloaded method");
     }
-    // Overloaded constructor:
+    // Calls overloaded constructor:
     new Tree();
   }
 }

interfaces/InterfaceCollision.java

@@ -12,12 +12,12 @@ class C2 implements I1, I2 {
   @Override
   public void f() {}
   @Override
-  public int f(int i) { return 1; } // overloaded
+  public int f(int i) { return 1; } // Overloaded
 }
 
 class C3 extends C implements I2 {
   @Override
-  public int f(int i) { return 1; } // overloaded
+  public int f(int i) { return 1; } // Overloaded
 }
 
 class C4 extends C implements I3 {

onjava/Range.java

@@ -2,33 +2,29 @@
 // (c)2021 MindView LLC: see Copyright.txt
 // We make no guarantees that this code is fit for any purpose.
 // Visit http://OnJava8.com for more book information.
-// Array creation methods that can be used without
-// qualifiers, using static imports:
+// Create arrays initialized with integer values.
 package onjava;
 
 public class Range {
-  // Produce a sequence [0..n)
-  public static int[] range(int n) {
-    int[] result = new int[n];
-    for(int i = 0; i < n; i++)
-      result[i] = i;
-    return result;
-  }
-  // Produce a sequence [start..end)
-  public static int[] range(int start, int end) {
-    int sz = end - start;
-    int[] result = new int[sz];
-    for(int i = 0; i < sz; i++)
-      result[i] = start + i;
-    return result;
-  }
   // Produce sequence [start..end) incrementing by step
   public static
   int[] range(int start, int end, int step) {
-    int sz = (end - start)/step;
+    if (step == 0)
+      throw new
+        IllegalArgumentException("Step cannot be zero");
+    int sz = Math.max(0, step >= 0 ?
+        (end + step - 1 - start) / step
+      : (end + step + 1 - start) / step);
     int[] result = new int[sz];
     for(int i = 0; i < sz; i++)
       result[i] = start + (i * step);
     return result;
+  }  // Produce a sequence [start..end)
+  public static int[] range(int start, int end) {
+    return range(start, end, 1);
+  }
+  // Produce a sequence [0..n)
+  public static int[] range(int n) {
+    return range(0, n);
   }
 }

onjava/TestRange.java

@@ -0,0 +1,29 @@
+// onjava/TestRange.java
+// (c)2021 MindView LLC: see Copyright.txt
+// We make no guarantees that this code is fit for any purpose.
+// Visit http://OnJava8.com for more book information.
+// Basic test of Range.java
+import static onjava.Range.*;
+import java.util.Arrays;
+
+public class TestRange {
+  private static void show(int[] rng) {
+    System.out.println(Arrays.toString(rng));
+  }
+  public static void main(String[] args) {
+    show(range(10, 21, 3));
+    show(range(21, 10, -3));
+    show(range(-5, 5, -3));
+    show(range(-5, 5, 3));
+    show(range(10, 21));
+    show(range(10));
+  }
+}
+/* Output:
+[10, 13, 16, 19]
+[21, 18, 15, 12]
+[]
+[-5, -2, 1, 4]
+[10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
+[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
+*/