Question

这是一个示例程序，它使用if语句使用用户输入弹出测试分数。

import java.util.Scanner;

public class testscore
{
public static void main (String [] args)
{
    Scanner sc = new Scanner (System.in);
    System.out.println ("Enter test score: ");
    int testscore = sc.nextInt();
    char grade;

    if (testscore >= 90) {
        grade = 'A';
    } else if (testscore >= 80) {
        grade = 'B';
    } else if (testscore >= 70) {
        grade = 'C';
    } else if (testscore >= 60) {
        grade = 'D';
    } else {
        grade = 'F';
    }
    System.out.println("Grade = " + grade);
}
}

这是我为饮料测试创建的程序

import java.util.Scanner;

public class drinktest
{
public static void main (String[] args)
{
    Scanner sc = new Scanner (System.in);
    System.out.println ("Enter The Amount Of Drinks You've Had: ");
    int drinknumber = sc.nextInt();
    char sober;

    if (drinknumber <=2) {sober = 'A';}
    else if (drinknumber <=3) {sober = 'B';}
    else if (drinknumber <=4) {sober = 'C';}
    else if (drinknumber <=5) {sober = 'D';}
    else if (drinknumber >=5) {sober = 'F';}

    System.out.println ("Your sobreity grade is: " + sober);
}
}

我遇到的问题是一切正常，直到它告诉我我的变量未初始化的最后一行。我没有在第一个程序中得到错误，据我所知它们是相同的。

我做错了什么？

Answer 1

就Java编译器所知，可能存在没有满足条件的流程，并且不会初始化此sober。只需将您的上一个else if更改为else，就可以了：

if (drinknumber <=2) {sober = 'A';}
else if (drinknumber <=3) {sober = 'B';}
else if (drinknumber <=4) {sober = 'C';}
else if (drinknumber <=5) {sober = 'D';}
else {sober = 'F';} // If none of the if's were met, it must be more than 5.

Answer 2

char sober = 0;

使用上面的代码。

Answer 3

您必须先初始化sober变量： char sober = 'F';

然后，在初始化变量之后，您可以执行if语句。但现在你不需要检查＆＃39; F＆＃39; F＆＃39;等级（它被初始化为＆＃39; F＆＃39;）所以请跳过这一部分： else if (drinknumber >=5) {sober = 'F';}

之后我们留下：

char sober = 'F';

if (drinknumber <=2) {sober = 'A';}
else if (drinknumber <=3) {sober = 'B';}
else if (drinknumber <=4) {sober = 'C';}
else if (drinknumber <=5) {sober = 'D';}

System.out.println ("Your sobreity grade is: " + sober);

如果 - 然后声明问题

3 个答案: