如果输入字符串值或与情况无关的数字，如何不获取错误

Question

如果输入字符串值或与大小写无关的数字，如何不获取错误。

switch(optionIssues) {
   case 1 : healthIssues = "Dental Problem"; ;break;
   case 2 : healthIssues = "Respiratory Diphtheria";;break;
   case 3 : healthIssues = "Mosquitoes Infections";;break;
}   

Answer 1

如果输入字符串，则可以通过将选项作为字符串读取或捕获异常来防止错误，如下所示：

int optionIssues;
try {
    optionIssues = new Scanner(System.in).nextInt();
}
catch (Exception e) {
    optionIssues = 0;
}

无论如何，您的开关中应该有一个默认的情况：

switch(optionIssues){
    case 1 : healthIssues = "Dental Problem"; break;
    case 2 : healthIssues = "Respiratory Diphtheria"; break;
    case 3 : healthIssues = "Mosquitoes Infections"; break;
    default: System.out.println("Invalid option.");
}

Answer 2

您应该添加这样的默认情况：

switch(optionIssues){
            case 1 : healthIssues = "Dental Problem";break;
            case 2 : healthIssues = "Respiratory Diphtheria";break;
            case 3 : healthIssues = "Mosquitoes Infections";break;
            default : break;
        }

您可以看到更多关于它的信息，这里

Answer 3

添加默认情况时，您将指示程序在所有情况都不满足时应该做什么。

switch(optionIssues){
            case 1 : healthIssues = "Dental Problem"; ;break;
            case 2 : healthIssues = "Respiratory Diphtheria";;break;
            case 3 : healthIssues = "Mosquitoes Infections";;break;
            default: 
                System.out.println("Introduce an integer between 1 and 3");
                break;
        }

如果您想在用户没有引入正确的选项时返回到交换机，您可以使用一个with循环，其结束条件如下：

boolean exit = false;
System.out.println("Introduce number 4 to finish");

while(!exit) {
    switch(optionIssues){
            case 1 : 
                healthIssues = "Dental Problem";
                break;
            case 2 : 
                healthIssues = "Respiratory Diphtheria";
                break;
            case 3 : 
                healthIssues = "Mosquitoes Infections";
                break;
            case 4 : 
                exit = true;
                break;
            default: 
                System.out.println("Introduce an integer between 1 and 4, please");
                break;
        }
}

这样，除非用户引入选项4，否则swith将被重复。如果您只想在引入了不正确的数字时重复它：

boolean repeat= true;

while(repeat) {
    switch(optionIssues){
            case 1 : 
                healthIssues = "Dental Problem";
                repeat = false;
                break;
            case 2 : 
                healthIssues = "Respiratory Diphtheria";
                repeat = false;
                break;
            case 3 : 
                healthIssues = "Mosquitoes Infections";
                repeat = false;
                break;
            default: 
                System.out.println("Introduce an integer between 1 and 4, please");
                break;
        }
}

如果用户引入一个5，则布尔重复是真的，所以它会重复。但是如果一个正确的数字，重复是假的，所以它会熄灭。