JavaExp6 exception handling plus assert assert

JavaExp6 exception handling

1. A construction method is added to the complex number class. The construction method has two string-type parameters, which are assigned to the real and imaginary parts of the complex number, respectively. In the construction method, first convert the string parameter to a floating point number and assign it to the real or imaginary part. When the contents of the string cannot be converted into floating-point numbers, a NumberFormatException is thrown. Handle the exception in the main function and test it.
   (Hint: Convert the string to a floating-point number by calling the static method parseDouble provided by the Double class. When the conversion fails, a numeric format exception NumberFormatException will be thrown and handled in the main function).

package EXP2020.exp6;
import java.io.*;

/**
 * @author JMChen
 * @date 2020/4/14
 */
class Complex {
    private double real, im;

    public Complex(String real, String im) {
        this.real = Double.parseDouble(real);
        this.im = Double.parseDouble(im);
    }

    public String toString() {
        if (im < 0)
            return "(" + this.real + "" + this.im + "i)";
        else
            return "(" + this.real + "+" + this.im + "i)";
    }

}


public class TestMainOne {
    public static void main(String[] args) {
        BufferedReader re = new BufferedReader(new InputStreamReader(System.in));

        String real = "";
        String im = "";
        System.out.println("请输入复数的实数和虚数部分：");
        while (true) {
            try {
                real = re.readLine();
                im = re.readLine();
                Complex complex = new Complex(real, im);
                System.out.println("复数为：" + complex.toString());
                break;
            } catch (NumberFormatException e) {
                System.out.println("输入的浮点格式有误，请重新输入：");
            } catch (Exception e) {
                e.printStackTrace();
            }

        }


    }
}

2. Customize illegal age class IleageAgeException, define a Person class, including age, name, gender and other attributes, write attribute setting and reading functions, in the setting age function, determine whether the parameters meet the requirements (1 ~ 150), if not Throw an exception; use the keyboard to enter the attribute value in the main function. When an exception occurs, the user is required to re-enter until the input is correct.

package EXP2020.exp6;
import java.util.Scanner;

/**
 * @author JMChen
 * @date 2020/4/14
 */
class IleageAgeException extends Exception {
    public IleageAgeException(String errorMassage) {
        super(errorMassage);
    }
}

class Person {
    protected int age;
    protected String name;
    public String sex;

    public void setAge(int age) throws IleageAgeException {
        if (age <= 0 || age > 150)
            throw new IleageAgeException("输入的年龄不符合要求");
        this.age = age;
    }

    public int getAge() {
        return age;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getSex() {
        return sex;
    }
}

public class TestMainTwo {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        Person person = new Person();
        while (true) {
            try {
                System.out.println("请依次输入年龄、姓名、性别：");
                person.setAge(sc.nextInt());
                person.setName(sc.next());
                person.setSex(sc.next());
                System.out.println("年龄：" + person.getAge());
                System.out.println("姓名：" + person.getName());
                System.out.println("性别：" + person.getSex());
                break;
            } catch (IleageAgeException e) {
                System.out.println(e.getMessage());
            }
        }

    }
}

3. 174 pages of textbook programming questions.

package EXP2020.exp6;
import java.util.*;
/**
 * @author JMChen
 * @date 2020/4/14
 */
public class TestMainThree {
    public static void main(String args[]) {
        Scanner reader = new Scanner(System.in);
        double sum = 0;
        int m = 0;
        while (reader.hasNextDouble()) {
            double x = reader.nextDouble();
            assert (x >= 0 && x <= 100) : "数据不合理";
            m = m + 1;
            sum = sum + x;
        }
        System.out.printf("%d个数的和为%f\n", m, sum);
        System.out.printf("%d个数的平均值是%f\n", m, sum / m);
    }
}

• TO SUM UP

Master the basic methods of java exception handling, with the ability to find and handle program errors, so that the application has stability and reliability.

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