将字符串转换为整数。字符串值 = 扫描仪输入.....很难解释

Question

好的，我正在尝试转换一些东西。

所以我已经将我的扫描仪转换为字符串，现在我要做的是，获取他们输入的值并将其用作几个 else if 语句的整数。它不会工作！

到目前为止，这是我的代码：

import java.util.Scanner;
public class apples {
public static void main(String args[]) {

    Scanner fname = new Scanner(System.in);
    Scanner sname = new Scanner(System.in);
    Scanner number = new Scanner(System.in);
    tuna weight = new tuna();

    System.out.println("Enter Your First Name: ");
    String fname1 = fname.nextLine();
    String fnames = fname1;

    System.out.println("Enter Your Last Name: ");
    String sname1 = sname.nextLine();
    String snames = sname1;

    System.out.println("Enter Your Weight (Lbs.) : ");
    String num = number.nextLine();
    String num1 = num;

    System.out.println("Okay " + fname1 + " " + sname1
            + " I can see here that you weigh " + num + "lbs.");
    int num2 = num1.parseInt();
    if (num1 >= 275)
        System.out
                .println("You know, you should maybe consider laying off the candy my friend.....");
}

}

Answer 1

你应该在parseInt中使用一个参数：

int num2 = Integer.parseInt(num1);

和

if (num2 >= 275) 
...

Answer 2

试试这个：

try{
  num2 = Integer.parseInt(num1);
}
catch(Exception ex) {
  System.out.println("Something went wrong, the string could not be converted to int.");
}

try-catch 非常重要，因为字符串可能包含无法转换为 int 的字符，因此您需要比这更好地捕捉它，但请记住这一点

Answer 3

您也可以使用其他类型的扫描仪方法来获取 int 值

num = number.nextInt();

Answer 4

这是我所做的：

Scanner input = new Scanner(System.in);
System.out.println("Type number");
int number = input.nextInt();
System.out.println(number);

希望这会有所帮助...

Answer 5

我自己不是 Java 专家，但我将您的代码调整了一个档次以使其正常工作。这里是。很高兴有帮助。

p

ackage APPLE;
import java.util.Scanner;
public class apples {
public static void main(String args[]) {

    Scanner fname = new Scanner(System.in);
    Scanner sname = new Scanner(System.in);
    Scanner number = new Scanner(System.in);
    Scanner intScanner = new Scanner(System.in);

    System.out.println("Enter Your First Name: ");
    String fname1 = fname.nextLine();
    String fnames = fname1;

    System.out.println("Enter Your Last Name: ");
    String sname1 = sname.nextLine();
    String snames = sname1;

    System.out.println("Enter Your Weight (Lbs.) : ");
    int num = intScanner.nextInt();


    System.out.println("Okay " + " " + fname1 + " " + sname1 
            + " I can see here that you weigh " + num + "lbs.");

    if (num > 275){
        System.out.println("You know, you should maybe consider laying off the candy my friend.....");
    }
}
}