我嘗試撰寫關于讀取數字的值 o 符號的編碼，并且我必須將空格作為輸入，我可以讀取并識別數字的值，但我可以讀取空白輸入并給出錯誤（例外在執行緒“主”java.lang.numberformatexception：輸入字串：“）
import java.util.Scanner;
public class CheckingSign {
public static void main (String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter floating point value: ");
String number = scanner.nextLine();
int n = Integer.parseInt(number);
if ( n > 0 ) {
System.out.print("DEBUG:the user input is < " number " >");
System.out.println("DEBUG:the trimed input is <" number ">");
System.out.println("The sign of the input is 1");
} else if ( n < 0 ) {
System.out.print("DEBUG:the user input is < " number " >");
System.out.println("DEBUG:the trimed input is <" number ">");
System.out.println("The sign of the input is -1");
} else {
System.out.print("DEBUG:the user input is < " number " >");
System.out.println("DEBUG:the trimed input is <" number ">");
System.out.println("Encountered blank input.");
}
}
}
uj5u.com熱心網友回復：
parse用try-catch陳述句包圍
Scanner scanner = new Scanner(System.in);
System.out.print("Enter floating point value: ");
String number = scanner.nextLine();
try {
float n = Float.parseFloat(number);
if ( n > 0 ) {
System.out.print("DEBUG:the user input is < " number " >");
System.out.println("DEBUG:the trimed input is <" number ">");
System.out.println("The sign of the input is 1");
} else if ( n < 0 ) {
System.out.print("DEBUG:the user input is < " number " >");
System.out.println("DEBUG:the trimed input is <" number ">");
System.out.println("The sign of the input is -1");
}
} catch (Exception e) {
System.out.print("DEBUG:the user input is < " number " >");
System.out.println("DEBUG:the trimed input is <" number ">");
System.out.println("Encountered blank input.");
}
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