[英]Java while loop doesn't work as intended
public static void main(String[] args) {
boolean run = true;
while (run) {
Scanner kb = new Scanner(System.in);
System.out.println("Welcome to MetricMan - the best converter in town!");
System.out.println("Choose and option:");
System.out.println("A) Fahrenheit to Celsius");
System.out.println("B) Celcius to Fahrenheit");
System.out.println("C) Miles to Kilometers");
System.out.println("D) Kilometers to Miles");
System.out.println("E) Inches to Centimeters");
System.out.println("F) Centimeters to Inches");
System.out.println("X) Quit the program");
System.out.print("Your choice > ");
String choice = kb.nextLine();
double output; int input;
System.out.print("Enter the number of ");
switch (choice) { // do actions according to the user's choice. convert and display
case "A":
System.out.print("Farenheit > ");
input = kb.nextInt();
output = convertFtoC(input);
System.out.println(input+" farenheit is "+output+" celsius");
break;
case "B":
System.out.print("Celsius > ");
input = kb.nextInt();
output = convertCtoF(input);
System.out.println(input+" celsius is "+output+" farenheit");
break;
case "C":
System.out.print("miles > ");
input = kb.nextInt();
output = convertMtoK(input);
System.out.println(input+" miles is "+output+" kilometres");
break;
case "D":
System.out.print("kilometres > ");
input = kb.nextInt();
output = convertKtoM(input);
System.out.println(input+" kilometres is "+output+" miles");
break;
case "E":
System.out.print("inches > ");
input = kb.nextInt();
output = convertItoC(input);
System.out.println(input+" inches is "+output+" centimeters");
break;
case "F":
System.out.print("centimeters > ");
input = kb.nextInt();
output = convertCtoI(input);
System.out.println(input+" centimeters is "+output+" inches");
break;
case "X":
System.out.println(); System.out.println();
System.out.println("May the odds be ever metric!");
run = false;
break;
}
System.out.println();
kb.nextLine();
}
} // end of main()
這是我的主要方法。 從代碼中可以看出,輸入X后,代碼應立即停止運行,但是實際輸出為
...
Your choice > X
Enter the number of
May the odds be ever metric!
在實際的預期輸出之前有一個“輸入數字”,我認為沒有理由在其中。 誰能幫忙解決此問題?
每次循環時都會出現該行。 解決此問題的一種方法是在每個case語句(X除外)中進行該調用。
在你的代碼中
System.out.print("Enter the number of ");
switch (choice) { // do actions according to the user's choice. convert and display
因此,您基本上是在切換之前打印此內容,因此可以預期輸出,您可能希望在內部實例而不是外部切換中調用它,當它的x退出時。
您正在做System.out.print("Enter the number of ");
在每種情況下。所以這就是為什么當您輸入X
時要進行打印,因此請嘗試放入System.out.print("Enter the number of ");
在if(check if string entered is not X)
內部if(check if string entered is not X)
如下
if(!choice.equals("X")){
System.out.print("Enter the number of ");
}
要么
把System.out.print("Enter the number of ");
在每個開關盒內,如@Tanmoy所指
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