Different types of Java variables and their usage

Common variable types in Java and how to use them

In Java programming, a variable is an element used to store data. There are different types of variables in Java depending on the data type. Understanding and correctly using these variable types is important for writing efficient, readable code. This article will introduce common variable types in Java, including integer types, floating point types, character types, Boolean types, and string types, and provide corresponding code examples.

1. Integer type

The integer type is a variable type used to store integer values. Java provides four integer types: byte, short, int and long. These types vary in scope and space. Choosing the appropriate type can improve the efficiency of your code.

1. byte type: The byte type is the smallest range integer type, between -128 and 127. Using the byte type can save memory space.

Sample code:

byte num1 = 10;
byte num2 = -5;

2. Short type: The short type can be used to represent a larger range of integers, with values ​​ranging from -32768 to 32767.

Sample code:

short num1 = 100;
short num2 = -200;

3. int type: int type is the most widely used integer type in Java. The default is 32 bits and the value range is -2147483648 to Between 2147483647.

Sample code:

int num1 = 1000;
int num2 = -2000;

4. long type: The long type can be used to store a larger range of integers. The value range is between -9223372036854775808 and 9223372036854775807. It needs to be in the numerical value Add "L" or "l" at the end to indicate long type.

Sample code:

long num1 = 1000000000000L;
long num2 = -2000000000000L;

2. Floating point type

The floating point type is used to store values ​​with decimal points. There are two floating point number types provided in Java: float and double. The precision of the double type is higher than that of the float type, so it is recommended to use the double type.

1. float type: A float type value needs to be represented as a float type by adding "F" or "f" after the value.

Sample code:

float num1 = 3.14F;
float num2 = -2.5F;

2. Double type: The double type can represent floating point numbers with a larger range and higher precision.

Sample code:

double num1 = 3.14159;
double num2 = -2.71828;

3. Character type

The character type is used to store a single character, which is represented by single quotes ' '.

Sample code:

char ch1 = 'A';
char ch2 = '中';

4. Boolean type

The Boolean type is used to store logical values ​​and has only two values: true and false. The Boolean type is suitable for judging conditions and control processes.

Sample code:

boolean flag1 = true;
boolean flag2 = false;

5. String type

The string type is the variable type used to store strings. In Java, a string is a class, and you can use quotes " " or double quotes " " to represent a string.

Sample code:

String str1 = "Hello";
String str2 = "World";

In summary, this article introduces the use of common variable types in Java and provides corresponding code examples. Understanding and using these variable types correctly will help you write efficient and readable Java code.

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