Java BASICS (1)-data types and java Basics

Java BASICS (1)-data types and java Basics

Java has two data types:

Basic data types and basic data types can be directly allocated to the stack.

Reference data type. The reference is stored in the stack, and the object is stored in the heap.

 

There are eight basic data types:

Class 1: char)

Type 2: logical (boolean)

Category 3: INTEGER (byte, short, int, long)

Category 4: float (float, double)

 

Char: 16-bit. It stores UNICODE codes and is assigned with single quotation marks.

Boolean: true, false

Byte: 8-bit,-128 ~ 127

Short: 16 bits,-2 ^ 15 ~ 2 ^ 15-1

Int: 32-bit,-2 ^ 31 ~ 2 ^ 31-1

Long: 64-bit,-2 ^ 63 ~ 2 ^ 63-1

Double: 64-bit, 4.9e-324 ~ 1.8e308. You can add d or D to a value, or do not add d to a value.

Float: 32-bit, 3.4e-45 ~ 1.4e38: f or F must be added after the number when the value is directly assigned.

 

Conversion Between Basic Data Types

There are two types: automatic conversion and forced conversion.

When small data is converted to big data, the program automatically converts

Forced conversion is required when big data is converted to small data, and precision may be lost.

Byte-> short

Char-> int-> long

Float-> double

Int-> float-> double

Long-> double