About java self-study content and feelings (7.21)

Directly to the point to talk about self-study content:

Define the legal identifier rules:

1. It may consist of letters, numbers, _ , $ components.
2. Start with a number and can not contain spaces.
3. Keywords and reserved words can not be used, but can contain keywords and reserved words.

byte short int long float double char boolean is . 8 kinds of basic data types are all other reference data types.

Integer types: byte ( -128-127 ), Short , int , Long .

Float Type: Double , a float (need to add the assignment after the number F );

Basic data type in the code I have written:

public class Test {

public static void main(String args[]) {

// output

System.out.println("helloworld！");

// simple integer variable is defined and adder

int i=3;

int b=2;

int c=i+b;

// output operation result

System.out.println("i+b="+c);

// float type definition

float k=1.22f;

// output variables

System.out.println(k);

// Get the maximum value of type float

float maxF=Float.MAX_VALUE;

// maximum output

System.out.println("maxF="+maxF);

// Get the minimum value of type double

double a=Double.MIN_VALUE;

// minimum output

System.out.println("a="+a);

// define a variable of type char

char c1='A';

// output variables

System.out.println(c1);

// define a String

String k1="helloworld";

// output

System.out.println(k1);

// define a String

String k2="he"+"llo"+"world";

// Check whether the output and consistent

System.out.println(k2);

// define Boolean

     Boolean b1=true;

// output

     System.out.println(b1);

}

}

Knock yourself by learning a lot of code, increasing the practical ability and increase your programming ability, I had a very fulfilling feeling. We will insist on self-study every day, knocking the code every day.