Getting Started with java|Operators

Started at: Introduction to java (3) | Operators
Start from scratch!!!

The last issue will cover eight basic types of java: int byte short long float double char boolean and the use of these eight basic types

This issue explains the use of operators in java. What operators do you know about them? You can learn how to use them. Let's start today.

operator

1. Overview

Logical Operator: The result is boolean type

& -- the relationship of yes and only (and)
    For 1 & 2 to get the final result true, the requirements for 1 and 2 are: both must be true

&& -- the relationship of yes and yes (double and/or short-circuit and)
    1 && 2, efficient, 2 will be short-circuited when 1 result is false

| -- Yes or Relationship
    1 | 2 To get the final result true, the requirements for 1 and 2 are: 1 or 2 can have one true


|| -- Yes or Relation (Double or/Short Circuit or)
    1 || 2, efficient, 2 will be short-circuited when the result of 1 is true

2. Exercise 1: Leap Year in Ordinary Year

Enter the year number to determine if it is a leap year.
Two conditions:
1. Can be divided by 4 and cannot be divided by 100
2. divisible by 400

package cn.qile.basic;

import java.util.Scanner;

public class Test4_RunNian {
    public static void main(String[] args) {

        //1. The year number entered by the receiving user
        System.out.print("Please enter a year:");
        int year = new Scanner(System.in).nextInt();

        //2. Determine whether year is a normal or leap year
        String desc = "Ordinary year";//Setting default value is flat year

        //If {code that meets the criteria}
//     1. Can be divided by 4 and cannot be divided by 100
        if (year % 4 == 0) { //Divisible by 4
            if (year % 100 != 0) { //Cannot be divisible by 100
                desc = "Leap year"; //Modify desc to leap year
            }
        }
//     2. divisible by 400
        if (year % 400 == 0) {
            desc = "Leap year"; //Modify desc to leap year
        }

//     System.out.println("Year 2000 is a leap year");
        //+Split String
        System.out.println(year + "Year is" + desc);

    }
}
Simplify Code

Through || -- Yes or Relationship (Double or/Short Circuit or)
-- 1 || 2, efficient, 2 will be short-circuited when the result of 1 is true

 //If ((small judgement 1 &&small judgement 2) ||big judgement 2) {modify desc value to leap year}
       if(( year%4==0  &&  year%100 != 0 )  ||  year%400 == 0  ){
           desc="Leap year";
       }

3. Exercise 2: Increase and Decrease

package cn.qile.basic;

//Test Self-Increasing++ Self-Decreasing--
public class Test5_ZiZeng {
    public static void main(String[] args) {
        //Symbol before, change before use
        //Symbol after, use before change
        int a = 1;
        System.out.println(a++);//1

        int b = 1;
        System.out.println(++b);//2
        System.out.println(++b+a+b++);//8,3+2+3

        //TODO Decrease
        int m = 1;
        System.out.println(m--);//1

        int n = 1;
        System.out.println(--n);//0
        System.out.println(--m-n-m--);//0,-1-0-(-1)
    }
}

4. Ternary operations

package cn.qile.basic;

import java.util.Scanner;

//Ternary operator
public class Test6_Max {
    public static void main(String[] args) {

        //Large values in two numbers
        int a = 10;
        int b = 6;

        //Ternary 1? 2: 3
        //The final result is 2 or 3, depending on the result of 1, if 1 is established, 2 is obtained, if 1 is not established, 3 is obtained.
        int max = a > b ? a : b ;
        System.out.println(max);

        //Receive keyboard input, three numbers, take out the maximum
        System.out.print("Please enter m =");
        int m = new Scanner(System.in).nextInt();
        System.out.print("Please enter n =");
        int n = new Scanner(System.in).nextInt();
        System.out.print("Please enter o =");
        int o = new Scanner(System.in).nextInt();

        //1. Define the maximum value of a variable record, hold the m to n ratio, and give the result to the variable to be saved
        int result = m > n ? m : n;

        //2. Hold result and o ratio to get the maximum value to be saved by maxValue
//     result = result > o ? result : o ;
        int maxValue = result > o ? result : o ;
        System.out.println(maxValue);

        //TODO optimization
        //Take m to n ratio? M to o ratio: n to O ratio
        int result2 = m > n ? (m > o ? m : o ) : (n > o ? n : o );
        System.out.println(result2);
    }

}

Next issue: Getting started with java (4) | Data types

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Tags: Programming Java

Posted on Thu, 11 Jun 2020 21:06:33 -0400 by shilpa_agarwal