Q.What is the difference between the = operator and the == operator? Give an example where confusing them causes a bug.

One of these stores a value and the other compares two values — a classic source of errors. …

= — assignment. This operator stores the value on its right into the variable on its left. It does not compare anything:

int x;
x = 5;      // x now holds 5

== — comparison. This relational operator checks whether two values are equal and produces a boolean result (true or false):

boolean same = (x == 5);   // same is true

Where confusing them bites. Conditions expect a boolean. Suppose you mean to test whether x equals 5:

if (x == 5) {            // correct: tests equality
    System.out.println("five");
}

If you accidentally write a single =:

if (x = 5) { ... }       // ERROR in Java
``` …

Believing == and = are interchangeable. Also, for comparing String contents, == is not reliable (it compares references) — the .equals() metho …