Java 如果输入不是bigDecimal，如何抛出异常并再次扫描？_Java

Java 如果输入不是bigDecimal，如何抛出异常并再次扫描？

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Java 如果输入不是bigDecimal，如何抛出异常并再次扫描？,java,Java,我想扫描bigDecimal，但是如果扫描的输入不是bigDecimal，它应该抛出一个自定义异常并再次扫描它我正在尝试下面的代码，但无法得出结论代码： Sacnner#hastNextBigDecimal在扫描键盘输入时没有意义。它可以在扫描文件或扫描仪上字符串对象的值时使用您可以按如下方式进行操作： import java.math.BigDecimal; import java.util.Scanner; class WrongInputException extends Exce

我想扫描bigDecimal，但是如果扫描的输入不是bigDecimal，它应该抛出一个自定义异常并再次扫描它

我正在尝试下面的代码，但无法得出结论

代码：

Sacnner#hastNextBigDecimal

在扫描键盘输入时没有意义。它可以在扫描文件或

扫描仪

上

字符串

对象的值时使用

您可以按如下方式进行操作：

import java.math.BigDecimal;
import java.util.Scanner;

class WrongInputException extends Exception {
    public WrongInputException(String message) {
        super(message);
    }
}

public class Main {
    public static void main(String[] args) throws WrongInputException {
        BigDecimal number;
        Scanner sc = new Scanner(System.in);
        System.out.print("Enter a BigDecimal: ");
        try {
            number = sc.nextBigDecimal();
            System.out.println(number);
        } catch (Exception e) {
            throw new WrongInputException("Wrong data type of input.....");
        }
    }
}

运行示例：

Enter a BigDecimal: 1234
1234

Enter a BigDecimal: xyz
Exception in thread "main" WrongInputException: Wrong data type of input.....
    at Main.main(Main.java:19)

import java.math.BigDecimal;
import java.util.Scanner;

class WrongInputException extends Exception {
    public WrongInputException(String message) {
        super(message);
    }
}

public class Main {
    public static void main(String[] args) throws WrongInputException {
        BigDecimal number = null;
        Scanner sc = new Scanner("123 987654321 12.34");
        try {
            while (sc.hasNextBigDecimal()) {
                number = sc.nextBigDecimal();
                System.out.println(number);
            }
        } catch (Exception e) {
            throw new WrongInputException("Wrong data type of input.....");
        }
    }
}

123
987654321
12.34

另一个示例运行：

Enter a BigDecimal: 1234
1234

Enter a BigDecimal: xyz
Exception in thread "main" WrongInputException: Wrong data type of input.....
    at Main.main(Main.java:19)

import java.math.BigDecimal;
import java.util.Scanner;

class WrongInputException extends Exception {
    public WrongInputException(String message) {
        super(message);
    }
}

public class Main {
    public static void main(String[] args) throws WrongInputException {
        BigDecimal number = null;
        Scanner sc = new Scanner("123 987654321 12.34");
        try {
            while (sc.hasNextBigDecimal()) {
                number = sc.nextBigDecimal();
                System.out.println(number);
            }
        } catch (Exception e) {
            throw new WrongInputException("Wrong data type of input.....");
        }
    }
}

123
987654321
12.34

在

字符串上的扫描仪的演示：

Enter a BigDecimal: 1234
1234

Enter a BigDecimal: xyz
Exception in thread "main" WrongInputException: Wrong data type of input.....
    at Main.main(Main.java:19)

import java.math.BigDecimal;
import java.util.Scanner;

class WrongInputException extends Exception {
    public WrongInputException(String message) {
        super(message);
    }
}

public class Main {
    public static void main(String[] args) throws WrongInputException {
        BigDecimal number = null;
        Scanner sc = new Scanner("123 987654321 12.34");
        try {
            while (sc.hasNextBigDecimal()) {
                number = sc.nextBigDecimal();
                System.out.println(number);
            }
        } catch (Exception e) {
            throw new WrongInputException("Wrong data type of input.....");
        }
    }
}

123
987654321
12.34

输出：
Enter a BigDecimal: 1234
1234

Enter a BigDecimal: xyz
Exception in thread "main" WrongInputException: Wrong data type of input.....
    at Main.main(Main.java:19)

import java.math.BigDecimal;
import java.util.Scanner;

class WrongInputException extends Exception {
    public WrongInputException(String message) {
        super(message);
    }
}

public class Main {
    public static void main(String[] args) throws WrongInputException {
        BigDecimal number = null;
        Scanner sc = new Scanner("123 987654321 12.34");
        try {
            while (sc.hasNextBigDecimal()) {
                number = sc.nextBigDecimal();
                System.out.println(number);
            }
        } catch (Exception e) {
            throw new WrongInputException("Wrong data type of input.....");
        }
    }
}

123
987654321
12.34

Sacnner#hastNextBigDecimal
在扫描键盘输入时没有意义。它可以在扫描文件或扫描仪
上字符串
对象的值时使用
您可以按如下方式进行操作：
import java.math.BigDecimal;
import java.util.Scanner;

class WrongInputException extends Exception {
    public WrongInputException(String message) {
        super(message);
    }
}

public class Main {
    public static void main(String[] args) throws WrongInputException {
        BigDecimal number;
        Scanner sc = new Scanner(System.in);
        System.out.print("Enter a BigDecimal: ");
        try {
            number = sc.nextBigDecimal();
            System.out.println(number);
        } catch (Exception e) {
            throw new WrongInputException("Wrong data type of input.....");
        }
    }
}

运行示例：
Enter a BigDecimal: 1234
1234

Enter a BigDecimal: xyz
Exception in thread "main" WrongInputException: Wrong data type of input.....
    at Main.main(Main.java:19)

import java.math.BigDecimal;
import java.util.Scanner;

class WrongInputException extends Exception {
    public WrongInputException(String message) {
        super(message);
    }
}

public class Main {
    public static void main(String[] args) throws WrongInputException {
        BigDecimal number = null;
        Scanner sc = new Scanner("123 987654321 12.34");
        try {
            while (sc.hasNextBigDecimal()) {
                number = sc.nextBigDecimal();
                System.out.println(number);
            }
        } catch (Exception e) {
            throw new WrongInputException("Wrong data type of input.....");
        }
    }
}

123
987654321
12.34

另一个示例运行：
Enter a BigDecimal: 1234
1234

Enter a BigDecimal: xyz
Exception in thread "main" WrongInputException: Wrong data type of input.....
    at Main.main(Main.java:19)

import java.math.BigDecimal;
import java.util.Scanner;

class WrongInputException extends Exception {
    public WrongInputException(String message) {
        super(message);
    }
}

public class Main {
    public static void main(String[] args) throws WrongInputException {
        BigDecimal number = null;
        Scanner sc = new Scanner("123 987654321 12.34");
        try {
            while (sc.hasNextBigDecimal()) {
                number = sc.nextBigDecimal();
                System.out.println(number);
            }
        } catch (Exception e) {
            throw new WrongInputException("Wrong data type of input.....");
        }
    }
}

123
987654321
12.34

在字符串上的扫描仪的演示：

Enter a BigDecimal: 1234
1234

Enter a BigDecimal: xyz
Exception in thread "main" WrongInputException: Wrong data type of input.....
    at Main.main(Main.java:19)

import java.math.BigDecimal;
import java.util.Scanner;

class WrongInputException extends Exception {
    public WrongInputException(String message) {
        super(message);
    }
}

public class Main {
    public static void main(String[] args) throws WrongInputException {
        BigDecimal number = null;
        Scanner sc = new Scanner("123 987654321 12.34");
        try {
            while (sc.hasNextBigDecimal()) {
                number = sc.nextBigDecimal();
                System.out.println(number);
            }
        } catch (Exception e) {
            throw new WrongInputException("Wrong data type of input.....");
        }
    }
}

123
987654321
12.34

输出：
Enter a BigDecimal: 1234
1234

Enter a BigDecimal: xyz
Exception in thread "main" WrongInputException: Wrong data type of input.....
    at Main.main(Main.java:19)

import java.math.BigDecimal;
import java.util.Scanner;

class WrongInputException extends Exception {
    public WrongInputException(String message) {
        super(message);
    }
}

public class Main {
    public static void main(String[] args) throws WrongInputException {
        BigDecimal number = null;
        Scanner sc = new Scanner("123 987654321 12.34");
        try {
            while (sc.hasNextBigDecimal()) {
                number = sc.nextBigDecimal();
                System.out.println(number);
            }
        } catch (Exception e) {
            throw new WrongInputException("Wrong data type of input.....");
        }
    }
}

123
987654321
12.34

问题是您没有处理抛出的异常
您应该添加一个try-catch块来在thw内部处理它，同时还应该添加一个sc.next（）以避免无休止的循环
 while (!sc.hasNextBigDecimal())
         {
            try {
             throw new WrongInputException("Wrong data type of input.....");

            }catch (WrongInputException e) {
                e.printStackTrace();
            }finally {
                sc.next();
            }
        }

请注意，try-catch没有意义，因为您有要抛出的异常
问题是您没有处理抛出的异常
您应该添加一个try-catch块来在thw内部处理它，同时还应该添加一个sc.next（）以避免无休止的循环
 while (!sc.hasNextBigDecimal())
         {
            try {
             throw new WrongInputException("Wrong data type of input.....");

            }catch (WrongInputException e) {
                e.printStackTrace();
            }finally {
                sc.next();
            }
        }

请注意，您的try-catch没有意义，因为您要抛出异常
什么不起作用？为什么要抛出异常？谁应该捕获此异常？什么不起作用？为什么要抛出异常？谁应该抓住这个例外？