Add Logical Operators lesson with Java

Author: dr-saad-la

SourceCode/chap_04-Operations/Lesson_03/LogicalOperators.java

@@ -0,0 +1,118 @@
+/*****************************************************************************
+ * PROJECT:    Java-101 Comprehensive Programming Course
+ * MODULE:     Introduction to Java Fundamentals
+ * LESSON:     4.3 - Logical Operators
+ *
+ * AUTHOR:     Dr. Saad Laouadi, Ph.D.
+ * CREATED:    April 2025
+ *
+ * Copyright © 2025 Dr. Saad Laouadi. All Rights Reserved.
+ * See LICENSE file for complete terms.
+ *****************************************************************************/
+
+public class LogicalOperators {
+    public static void main(String[] args) {
+        // Variables for demonstration
+        boolean p = true;
+        boolean q = false;
+        int a = 10;
+        int b = 20;
+
+        displayBanner('*', 72);
+        System.out.println("LOGICAL OPERATORS DEMONSTRATION");
+        System.out.println("===============================");
+        System.out.println("Working with variables: p = " + p + ", q = " + q);
+        System.out.println("And numeric values: a = " + a + ", b = " + b);
+
+        // Logical AND operator (&&)
+        System.out.println("\n1. Logical AND (&&)");
+        System.out.println("   p && p: " + (p && p) + " (true AND true = true)");
+        System.out.println("   p && q: " + (p && q) + " (true AND false = false)");
+        System.out.println("   q && p: " + (q && p) + " (false AND true = false)");
+        System.out.println("   q && q: " + (q && q) + " (false AND false = false)");
+
+        System.out.println("\n   Example with conditions:");
+        System.out.println("   (a < b) && (a > 5): " + ((a < b) && (a > 5)) +
+                          " (both conditions true)");
+        System.out.println("   (a > b) && (a > 5): " + ((a > b) && (a > 5)) +
+                          " (first condition false, second true)");
+
+        // Logical OR operator (||)
+        System.out.println("\n2. Logical OR (||)");
+        System.out.println("   p || p: " + (p || p) + " (true OR true = true)");
+        System.out.println("   p || q: " + (p || q) + " (true OR false = true)");
+        System.out.println("   q || p: " + (q || p) + " (false OR true = true)");
+        System.out.println("   q || q: " + (q || q) + " (false OR false = false)");
+
+        System.out.println("\n   Example with conditions:");
+        System.out.println("   (a < b) || (a > 5): " + ((a < b) || (a > 5)) +
+                          " (both conditions true)");
+        System.out.println("   (a > b) || (a > 5): " + ((a > b) || (a > 5)) +
+                          " (first condition false, second true)");
+        System.out.println("   (a > b) || (a < 5): " + ((a > b) || (a < 5)) +
+                          " (both conditions false)");
+
+        // Logical NOT operator (!)
+        System.out.println("\n3. Logical NOT (!)");
+        System.out.println("   !p: " + (!p) + " (NOT true = false)");
+        System.out.println("   !q: " + (!q) + " (NOT false = true)");
+        System.out.println("   !(a < b): " + (!(a < b)) + " (NOT true = false)");
+        System.out.println("   !(a > b): " + (!(a > b)) + " (NOT false = true)");
+
+        // Short-circuit evaluation
+        System.out.println("\n4. Short-Circuit Evaluation");
+        System.out.println("   In logical expressions, Java uses short-circuit evaluation.");
+        System.out.println("   This means the second condition is only evaluated if needed.");
+
+        // Short-circuit AND
+        System.out.println("\n   Short-Circuit AND Example:");
+        System.out.println("   false && (any expression): Second expression is never evaluated");
+
+        boolean result1 = q && isPositive(0);
+        System.out.println("   q && isPositive(0): " + result1 +
+                          " (second expression not evaluated because q is false)");
+
+        // Short-circuit OR
+        System.out.println("\n   Short-Circuit OR Example:");
+        System.out.println("   true || (any expression): Second expression is never evaluated");
+
+        boolean result2 = p || isPositive(0);
+        System.out.println("   p || isPositive(0): " + result2 +
+                          " (second expression not evaluated because p is true)");
+
+        // Combining logical operators
+        System.out.println("\n5. Combining Logical Operators");
+        boolean complexExpression = (a > 5) && (b < 30) || (a + b > 25);
+        System.out.println("   (a > 5) && (b < 30) || (a + b > 25): " + complexExpression);
+        System.out.println("   Precedence: AND is evaluated before OR");
+
+        boolean withParentheses = (a > 5) && ((b < 30) || (a + b > 25));
+        System.out.println("   (a > 5) && ((b < 30) || (a + b > 25)): " + withParentheses);
+        System.out.println("   Parentheses change the order of evaluation");
+
+        // Using logical operators in control flow
+        System.out.println("\nUsing Logical Operators in Control Flow:");
+
+        if (a < b && a > 5) {
+            System.out.println("   a is less than b AND a is greater than 5");
+        }
+
+        if (a > b || a > 5) {
+            System.out.println("   a is greater than b OR a is greater than 5");
+        }
+
+        displayBanner('*', 72);
+    }
+
+    // Helper method to demonstrate short-circuit evaluation
+    public static boolean isPositive(int num) {
+        System.out.println("   isPositive() method was called!");
+        return num > 0;
+    }
+    static void displayBanner(char c, int length){
+        for (int i=0; i<length; i++){
+            System.out.print(c);
+        }
+        System.out.println();
+    }
+}