Java Programming Basics – Data types

2.1 Variables and Data types:

2.1.1 Data Type:

Data types: Java is a strongly typed language, with explicit data types defined for each type of data

Data type: Basic data type + reference data type

2.1.1.1 Basic Data types

One with eight basic data types:

package day_05_25;
/* * There are several types of data in Java: * two basic data types and reference data types * How many basic data types are there: * 8: * byte short int long float double Boolean char * * A: scope: * A variable is valid within the braces {} in which it is defined, and the same variable name cannot be defined within the same braces. * a: datatype variable name = initial value; a: datatype variable name = initial value; * b: data type variable name; * Variable name = initial value * * */
public class demo02 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		int k=23,j;
		j=24;
		System.out.println(j);
		
		byte b = 23;// bytes (low frequency)
		short s =21313;// Short integers have the maximum number of five digits
		int i = 231231321;/ / integer
		long l = 231313131313131313l;// Long integer, followed by L
		 double d = 2.131;// Double precision, decimal point
		 float f = 2.313 F; // Single precision, then add F
		 boolean bf = false;
		 boolean bt = true;
		 
		 // Do not use:
		 char c= 'A';
		 char c1 = 'in';
		 char c2 = ', '; }}Copy the code

2.1.1.2 Reference Types

One kind consists of five kinds:

The reference type corresponding to the base data type