java basic knowledge review-2 (boolean short-circuit problem, operator precedence and reference data type)

1 Short-circuit and &&, when its left side is false, the right side is not executed;

   Short circuit or ||, when its left is true, the right is not executed.

2 int a=1；

   if（a++==2）{

   a = 7；

 }

System.out.println(a);

The output result is 2, because when ++ is to the right of a, first determine whether a is equal to 2, and then add 1; when ++ is to the left of a, first add 1, and then determine whether it is equal to 2

3 Quoting the Scanner data type format:

First import the package outside the class import java.util.Scanner;

Then create a new object of this data type in the class Scanner sc = new Scanner(System.in);

Then call the function                                              　　　int i = sc.nextInt() in the object; //Used to receive the number entered by the console

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　String s = sc.next();// used to receive the string entered by the console

4 Reference Random data type format

First import the package outside the class import java.util.Random;

Then create a new object of the data type in the class Random rd = new Random(); then call the function in the object                                              　　　

Then call the function                                                         int i = rd.nextInt(10) in the object; // used to receive the random integer of [0,10)

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　double s = rd.nextDouble();// Random decimals used to receive [0.0, 1.0]