In Java programming, consider the following code fragment: int Output = 10; boolean b = false; if ((b == true) && ((Output += 10) == 20)) { System.out.println("We are equal " + Output); } else { System.out.println("Not equal! " + Output); } What happens when this code is compiled and executed?

Introduction / Context:
This Java question examines how boolean expressions, the equality operator, and the logical AND operator behave at runtime, as well as whether modifying a variable inside a conditional expression is legal. It focuses on the concept of short circuit evaluation with the logical AND operator and how that affects whether certain sub expressions are evaluated, in turn affecting the final value printed to the console.

Given Data / Assumptions:

• Output is an integer variable initialised to 10.
• b is a boolean variable initialised to false.
• The if condition is (b == true) && ((Output += 10) == 20).
• The then block prints We are equal followed by Output.
• The else block prints Not equal! followed by Output.

Concept / Approach:
In Java, the operator == compares primitive values for equality, including boolean values. The logical AND operator && uses short circuit evaluation, meaning that if the left side of the expression evaluates to false, the right side is not evaluated at all. Incrementing Output using Output += 10 inside the condition is legal syntax, but it will only occur if that part of the expression is evaluated. Understanding these rules allows us to determine whether Output changes and which branch of the if statement executes.

Step-by-Step Solution:
Step 1: Evaluate the left side of the logical AND expression: b == true. Since b is false, b == true evaluates to false. Step 2: Because the left operand of && is false, Java performs short circuit evaluation and does not evaluate the right operand ((Output += 10) == 20). Step 3: Since the right side is not evaluated, Output remains 10 and is not incremented. Step 4: The overall if condition evaluates to false, so the else branch executes. Step 5: The else branch prints Not equal! 10 to the console, indicating that Output stayed at its original value of 10.

Verification / Alternative check:
You can mentally trace or actually run this code in a Java environment to see that no compilation error occurs and that short circuit evaluation prevents any change to Output. Both the syntax of the condition and the modification of Output inside the expression are legal, and Java consistently applies the rule that the right side of && is skipped if the left side is false. This leads to the else branch being chosen and Output retaining its original value of 10.

Why Other Options Are Wrong:
Option A is incorrect because the then branch never executes; the condition is false. Option C is wrong because comparing booleans with == is valid in Java. Option D is incorrect because Output is never incremented, so it cannot become 20. Option E is wrong because modifying a variable inside a conditional expression is allowed in Java; there is no compilation error due to Output += 10.

Common Pitfalls:
Many learners forget about short circuit evaluation and assume that both sides of the && expression are always evaluated, leading them to think that Output becomes 20. Others incorrectly believe that Java forbids assignments inside if conditions. It is important to remember that && may skip evaluation of the second operand if the first operand is false, and that assignments inside expressions are permitted, though they should be used carefully for clarity.

Final Answer:
The code compiles successfully and the else branch executes, so the output is Not equal! 10.