> ## Documentation Index
> Fetch the complete documentation index at: https://docs.syntblaze.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Java Bitwise Complement
The `~` (bitwise complement) operator is a unary operator that performs a logical negation on each individual bit of an integral data type. It evaluates the binary representation of its operand and inverts it, flipping every `0` to `1` and every `1` to `0`.
```java theme={"dark"}
~operand
```
## Mathematical Equivalence
Because Java represents signed integers using two's complement, applying the bitwise complement operator to any integer `n` mathematically yields `-(n + 1)`.
```java theme={"dark"}
int n = 12;
int result = ~n; // Evaluates to -13
```
## Bit-Level Mechanics
When applied to a 32-bit `int`, the operator transforms the entire 32-bit sequence, including the sign bit.
```java theme={"dark"}
int a = 5;
// Binary of a: 00000000 00000000 00000000 00000101
int b = ~a;
// Binary of b: 11111111 11111111 11111111 11111010
// Decimal of b: -6
```
## Unary Numeric Promotion
The `~` operator triggers Java's unary numeric promotion rules. If the operand is of type `byte`, `short`, or `char`, the Java Virtual Machine (JVM) automatically widens it to a 32-bit `int` *before* applying the bitwise inversion. Consequently, the return type of the operation is always an `int` (unless the operand is a `long`, in which case the return type remains a 64-bit `long`).
```java theme={"dark"}
byte x = 2;
// byte y = ~x;
// Compilation Error: Incompatible types. Possible lossy conversion from int to byte.
int y = ~x; // Correct: The evaluated result is an int.
byte z = (byte) ~x; // Correct: Explicit downcast required to assign back to a byte.
```
In the promotion example above, the 8-bit `byte` (`00000010`) is first sign-extended to a 32-bit `int` (`00000000 00000000 00000000 00000010`), and then all 32 bits are inverted. If explicitly cast back to a `byte`, the upper 24 bits are truncated.
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