Question

Construct the Java statement that produced the following IJVM code: ILOAD j ILOAD n ISUB BIPUSH 21 IADD DUP IADD ISTORE į a) Show what the stack is doing for each instruction b) Comment the IJVM code with useful comments c) Write the JAVA CODE that is being executed by the IJVM code.

Answer 1

Step-by-step explanation:

a) Let's analyze the stack for each IJVM instruction:

ILOAD j: Loads the value of variable j onto the stack.

Stack: [j]

ILOAD n: Loads the value of variable n onto the stack.

Stack: [j, n]

ISUB: Subtracts the top two values on the stack (n - j).

Stack: [n - j]

BIPUSH 21: Pushes the constant value 21 onto the stack.

Stack: [n - j, 21]

IADD: Adds the top two values on the stack ((n - j) + 21).

Stack: [n - j + 21]

DUP: Duplicates the top value on the stack.

Stack: [n - j + 21, n - j + 21]

IADD: Adds the top two values on the stack ((n - j + 21) + (n - j + 21)).

Stack: [2 * (n - j) + 42]

ISTORE į: Stores the top value on the stack into variable į.

Stack: []

b) IJVM code with comments:

ILOAD j // Load value of variable j onto the stack

ILOAD n // Load value of variable n onto the stack

ISUB // Subtract n - j

BIPUSH 21 // Push constant value 21 onto the stack

IADD // Add (n - j) + 21

DUP // Duplicate the top value on the stack

IADD // Add top two values on the stack (2 * (n - j) + 42)

ISTORE į // Store the top value on the stack into variable į

c) The equivalent Java code for the provided IJVM code:

int result = 2 * (n - j) + 42;

į = result;

Note: In the Java code, the variables j, n, and į should be declared and assigned appropriate values before executing the code.