java.lang · java.base · since Java 1.0

Integer

declaration

public final class Integer extends Number
        implements Comparable<Integer>, Constable

Immutable box for int, plus the static utility home for parsing, comparing, and bit-twiddling ints. Autoboxing caches −128…127 — the root of famous == surprises.

Key methods

`static int parseInt(String s)`	String → int; NumberFormatException on garbage.
`static Integer valueOf(int i)`	Boxing entry — cached for −128…127.
`static int compare(int a, int b)`	Overflow-safe comparison (never a - b).
`static int max/min/sum(int, int)`	Method-reference-friendly arithmetic.
`static String toBinaryString/toHexString(int)`	Radix views.
`static int bitCount(int) / highestOneBit(int)`	Bit tricks, JIT-intrinsified.
`MIN_VALUE / MAX_VALUE`	−2³¹ and 2³¹−1 constants.