Overflow and mixed types

An int has 32 bits: values from −2³¹ (−2147483648) to 2³¹ − 1 (2147483647).

Overflow wraps around silently:

int big = 2147483647;
big = big + 1;
System.out.println(big);    // -2147483648 — wrapped!

Two int-only operators the exam loves:

• + on ints with Strings: "score: " + 90 → "score: 90" (concatenation). Left to right: 1 + 2 + "x" → "3x", but "x" + 1 + 2 → "x12".
• % (remainder) works on negatives with the sign of the dividend: -7 % 3 is -1.

char participates in arithmetic through its Unicode value:

char c = 'A';            // 65
char next = (char) (c + 1);   // 'B'

Casting an int that is out of char's range produces a different character — another silent wrap.