java - 我想检查负数和非数

Question

我有代码来检查非数字，但也希望包括对负数的检查。如果数字为负数或不是数字，则必须重新输入信息。我尝试输入 if(depValue < 0)....之后try{和之前catch但这没有用。如果我将 if 语句放在 while 循环之后，对我来说没有意义。

String depIn = "";
BufferedReader depositInput = new BufferedReader(new InputStreamReader(System.in));
while(true){
     System.out.print("Amount to deposit: ");                   
     depIn = depositInput.readLine();
     double depValue = 0.00;
     try{
          depValue = Double.parseDouble(depIn);
          break;
     }
     catch(NumberFormatException ne){
          System.out.println("You did not enter a number!");
     }
}

Answer 1

当您获得所需的数字时，您可以跳出循环。

double depValue;
while(true){
     System.out.print("Amount to deposit: ");                   
     depIn = depositInput.readLine();
     try {
          if ((depValue = Double.parseDouble(depIn)) > 0)
              break;
          System.out.println("The number needs to be positive!");
     } catch(NumberFormatException ne) {
          System.out.println("You did not enter a number!");
     }
}