1 · Foundations · lesson 4 of 41

Operators & Expressions

Arithmetic, comparison, logical and bitwise — and Java's promotion rules.

Java

int  sum   = 5 + 3;      // 8
int  div   = 7 / 2;      // 3  (integer division!)
double d   = 7 / 2.0;    // 3.5
int  mod   = 10 % 3;     // 1
boolean eq = (a == b);   // reference equality for objects
boolean ok = ready && !done;
int mask   = flags & 0xFF;   // bitwise AND

WATCH OUT

== on Strings compares references, not content. Use .equals() to compare values.

Key takeaways

✓Integer / integer = integer. Promote one side to get a double.
✓&& and || short-circuit; & and | do not (and also work bitwise).
✓For objects, == checks identity, .equals() checks value.

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