[BAEL-3152] - Examples for the article 'Using the Not Operator in If (#8368)

Conditions in Java'

core-java-modules/core-java-lang-syntax-2/src/main/java/com/baeldung/core/operators/notoperator/NotOperator.java

@@ -0,0 +1,99 @@
+package com.baeldung.core.operators.notoperator;
+
+/**
+ * Examples used in the article `Using the Not Operator in If Conditions in Java`.
+ */
+public class NotOperator {
+
+    public static void ifElseStatementExample() {
+        boolean isValid = true;
+
+        if (isValid) {
+            System.out.println("Valid");
+        } else {
+            System.out.println("Invalid");
+        }
+    }
+
+    public static void checkIsValidIsFalseWithEmptyIfBlock() {
+        boolean isValid = true;
+
+        if (isValid) {
+
+        } else {
+            System.out.println("Invalid");
+        }
+    }
+
+    public static void checkIsValidIsFalseWithJustTheIfBlock() {
+        boolean isValid = true;
+
+        if (isValid == false) {
+            System.out.println("Invalid");
+        }
+    }
+
+    public static void checkIsValidIsFalseWithTheNotOperator() {
+        boolean isValid = true;
+
+        if (!isValid) {
+            System.out.println("Invalid");
+        }
+    }
+
+    public static void notOperatorWithBooleanValueAsOperand() {
+        System.out.println(!true);   // prints false
+        System.out.println(!false);  // prints true
+        System.out.println(!!false); // prints false
+    }
+
+    public static void applyNotOperatorToAnExpression_example1() {
+        int count = 2;
+
+        System.out.println(!(count > 2));  // prints true
+        System.out.println(!(count <= 2)); // prints false
+    }
+
+    public static void applyNotOperatorToAnExpression_LogicalOperators() {
+        boolean x = true;
+        boolean y = false;
+
+        System.out.println(!(x && y));  // prints true
+        System.out.println(!(x || y));  // prints false
+    }
+
+    public static void precedence_example() {
+        boolean x = true;
+        boolean y = false;
+
+        System.out.println(!x && y);   // prints false
+        System.out.println(!(x && y)); // prints true
+    }
+
+    public static void pitfalls_ComplexConditionsExample() {
+        int count = 9;
+        int total = 100;
+
+        if (!(count >= 10 || total >= 1000)) {
+            System.out.println("Some more work to do");
+        }
+    }
+
+    public static void pitfalls_simplifyComplexConditionsByReversingLogicExample() {
+        int count = 9;
+        int total = 100;
+
+        if (count < 10 && total < 1000) {
+            System.out.println("Some more work to do");
+        }
+    }
+
+    public static void exitEarlyExample() {
+        boolean isValid = false;
+
+        if(!isValid) {
+            throw new IllegalArgumentException("Invalid input");
+        }
+        // Code to execute when isValid == true goes here
+    }
+}