创建复查if语句

Question

我正在为我的班级做一个年级平均脚本，我无法计算如何让我的交叉检查部分重复，直到我有一个有效值（代码如下所示）。运行时，如果原始输入无效，但只能执行一次，则允许我进行更正。我如何才能循环，直到我得到正确的回应？提前致谢！

if (grade1 >= 0 && grade1 <= 100) 
    System.out.println("First grade valid.\n"); 
    else 
    { 
     System.out.println("Grade invalid. Re-enter first grade:"); 
     grade1 = kb.nextDouble(); 
    } 

Answer 1

考虑

grade = -1; 
System.out.println("Enter a grade:\n"); 
grade1 = kb.nextDouble(); 
if (grade1 >= 0 && grade1 <= 100) 
{ 
    System.out.println("First grade valid.\n"); 
} 
else 
{ 
    while (grade1 < 0 || grade1 > 100) 
    { 
     System.out.println("Grade invalid. Re-enter first grade:"); 
     grade1 = kb.nextDouble(); 
    } 
} 

Answer 2

试试这个：

while ((grade = Integer.parseInt(JOptionPane.showInputDialog("Enter a grade"))) < 0 || grade > 100) { 
    System.out.println("Invalid grade of: " + grade); 
} 

它不处理信件很好不过，如果你输入 “A” ITLL抱怨，你

Answer 3

甜心吆喝，作为最初执行的方法，我进行了设置，以便用户在输入后插入输入并交叉检查其有效性ered（见下面的第一段摘录）。如果我能够主动交叉检查初始输入（见下面第二段摘录），最好节省空间。卢布洛克，我明白你在做什么，这是我的一个小小的疏忽。从现在起，我的反应会更好。

//交叉检查

if (grade1 >= 0 && grade1 <= 100) 
    System.out.println("First grade valid.\n"); 
    else 
    { 
     System.out.println("Grade invalid. Re-enter first grade:"); 
     grade1 = kb.nextDouble(); 
    } 

//入门级

grade1 = kb.nextDouble(); 
    while (grade1 < 0 || grade1 > 100) 
    { 
    System.out.println("Entered grade is invalid. Re-enter grade:"); 
    grade1 = kb.nextDouble(); 
    } 

Answer 4

try (Scanner scanner = new Scanner(System.in)) { 
    System.out.println("Enter a grade:\n"); 
    double grade1 = scanner.nextDouble(); 
    if (grade1 >= 0 && grade1 <= 100) 
    { 
     System.out.println("First grade valid.\n"); 
    } 
    else 
    { 
     while (grade1 < 0 || grade1 > 100) 
     { 
      System.out.println("Grade invalid. Re-enter first grade:"); 
      grade1 = scanner.nextDouble(); 
     } 
    } 
}