Casting and Ranges of Variables in Java

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Casting in Java

Casting in Java is used to convert a variable from one data type to another. There are two types of casting: implicit casting (automatic type conversion) and explicit casting (manual type conversion).

Implicit Casting (Widening Conversion):

Happens automatically when converting a smaller data type to a larger data type.

No data loss occurs.

Example:

Explicit Casting (Narrowing Conversion):

Must be done manually.

There can be data loss.

Example:

Ranges of Variables

Different data types in Java have different ranges, based on the number of bits used to store them. Here are the ranges for some common primitive data types:

byte:

Size: 8 bits

Range: -128 to 127

Example:

short:

Size: 16 bits

Range: -32,768 to 32,767

Example:

int:

Size: 32 bits

Range: -2^31 to 2^31-1 (approximately -2.1 billion to 2.1 billion)

Example:

long:

Size: 64 bits

Range: -2^63 to 2^63-1 (approximately -9.2 quintillion to 9.2 quintillion)

Example:

float:

Size: 32 bits

Range: Approximately ±3.40282347E+38F (6-7 significant decimal digits)

Example:

double:

Size: 64 bits

Range: Approximately ±1.79769313486231570E+308 (15 significant decimal digits)

Example:

char:

Size: 16 bits

Range: 0 to 65,535 (unsigned)

Example:

boolean:

Size: Not precisely defined; typically 1 bit

Values: true or false

Example:

Example: Combining Casting and Range

When working with different data types, it’s crucial to be aware of their ranges and ensure that the casting does not lead to unexpected results due to range overflow or truncation.

In this example, intVal is cast to a byte, which causes overflow because the byte range is only -128 to 127. Therefore, the output for byteVal is -128, demonstrating the importance of understanding variable ranges when casting.