Question

我是Java的初学者，我正在学习if语句没有 else，请社区检查我的代码以改进吗？

问题陈述： 在这段代码中，我们只使用if语句来练习。在这里，你需要输入你的年龄进入酒吧和热辣的女孩，如果你的年龄高于18岁，你可以进入。如果它低于18，你就无法进入。

import java.util.Scanner;

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

        Scanner input = new Scanner(System.in);

        int age;

        // Ask the age
        System.out.println("Please write your age to enter to the bar:");
        age = input.nextInt();

        // Equal to
        if(age == 18){
            System.out.println("Your age " + age + " it's equal to 18, you can enter");
        }

        // Not equal to
        if(age != 18){
            System.out.println("Your age " + age + " it's not equal to 18");
        }

        // Greater than
        if(age > 18){
            System.out.println("Your age " + age +  " " + "is greater than 18, you can enter");
        }

        // Less than
        if(age < 18){
            System.out.println("Your age " + age + " " + "is less than 18, you can't enter");
        }

        // Greater than or equal to
        if(age >= 18){
            System.out.println("Your age " + age + " is greater than or equal to 18, you can enter");
        }
        // Less than or equal to
        if(age <= 18){
            System.out.println("Your age " + age + " is less than or equal to 18, you can't enter");
        }
    }
}

Answer 1

从技术上讲，你只有三个案例：

age < 18
age == 18
age > 18

因此，您可以将代码简化为

...
if (age < 18) {
  System.out.println("Your age " + age + " it's not equal to 18");
  System.out.println("Your age " + age + " is less than 18, you can't enter");
  System.out.println("Your age " + age + " is less than or equal to 18, you can't enter");
}

// "else if" instead of "if" will make the code more readable   
if (age == 18) {
  System.out.println("Your age " + age + " it's equal to 18, you can enter");
  System.out.println("Your age " + age + " is greater than or equal to 18, you can enter"); 
  System.out.println("Your age " + age + " is less than or equal to 18, you can't enter");
}   

// "else" instead of "if" will make the code more readable   
if (age > 18) {
  System.out.println("Your age " + age + " it's not equal to 18");
  System.out.println("Your age " + age + " is greater than 18, you can enter");
  System.out.println("Your age " + age + " is greater than or equal to 18, you can enter");
}

如果您想确保age >= 18：

if (age >= 18) {
  System.out.println("Your age " + age + " is greater than or equal to 18, you can enter");
}

// "else" is a better choice here
if (age < 18) {
  System.out.println("Your age " + age + " is less than 18, you can't enter");  
}

Answer 2

你的代码很好，除了最后一个if语句应该小于，不等于或小于，并且最后两个之前的所有if语句都是无关的，所以你可以删除它们。你只需要考虑两种可能性：这个人是18岁以上，或者是18岁以下的人。

Answer 3

您的代码将“正常工作”，因为它将为每个年龄输入打印注释。但是因为你不使用else或嵌套，它总会产生多个注释。例如：如果输入17，则它将触发对＆lt;＆gt; 18的评论，＆lt;对于18的特定输入，其中一个打印的注释将与其他注释冲突，因为= 18和＆gt; = 18注释将允许您进入，而＆lt; = 18注释会拒绝你入境。

Answer 4

如果您只需要使用'if'，它的使用在您的代码中是正确的，但您的条件正在重复。提示：如果一个人的年龄应该是20，那么你的代码的第二，第三和第五个条件将成立，所有这些都将输出。正如你在问题中所说的那样，你需要检查年龄是大于还是小于18，如果你想检查它是否等于18，所以如果条件允许的话，你只需要两个

Answer 5

这里有一个方法，用于计算用户是否成人尊重now（）

public Boolean isMaggiorenne(Date dataGenerica) {
Boolean isMagg = false;
if (dataGenerica != null && dataNascita != null) {

GregorianCalendar dataDiNascita = new GregorianCalendar();
dataDiNascita.setTime(dataNascita);

GregorianCalendar dataMagg = new GregorianCalendar();
dataMagg.setTime(dataGenerica);

int anno = dataMagg.get(GregorianCalendar.YEAR) – dataDiNascita.get(GregorianCalendar.YEAR);
int mese = dataMagg.get(GregorianCalendar.MONTH) – dataDiNascita.get(GregorianCalendar.MONTH);
int giorno = dataMagg.get(GregorianCalendar.DAY_OF_MONTH) – dataDiNascita.get(GregorianCalendar.DAY_OF_MONTH);

isMagg = anno>18 || (anno==18 && (mese>0 || (mese==0 && giorno>=0))) ;
}
return isMagg;
}

这里有最高精度！

使用if语句

5 个答案: