Which of the following is a valid Java declaration?

int num = 'B';

Reason — Let's analyze each of the options:

1. float x = 12.5; — Incorrect

• A floating-point literal (like 12.5) is by default double in Java.
• To store it in a float variable, explicitly specify f or F:
  float x = 12.5f; // Corrected version

2. char ch = "A"; — Incorrect

• A char must be enclosed in single quotes (''), not double quotes ("").
• Correct version:
  char ch = 'A';

3. boolean b = 0; — Incorrect

• Java does not allow assigning integers (0 or 1) to boolean.
• Only true or false is allowed.
• Correct version:
  boolean b = false;

4. int num = 'B'; — Correct

• A char in Java can be assigned to an int because characters are internally stored as Unicode values (ASCII-compatible).
• 'B' corresponds to Unicode 66, so num will store 66.