Question

请帮我完成我的任务

编写程序来测试下面定义的Person类。你的测试程序应该创建两个类的实例（每个用于测试不同的构造函数）并测试每个方法。你是还需要说明尝试从客户端类访问私有数据成员时的错误（为清楚起见，暂时将private修饰符更改为public并再次测试）。查看截图下面是样本输出。

屏幕截图显示为：

p1 name = Not Given Age = 0 Gender = U
p2 name = Jane Doe Age = 0 Gender = F
p1 name = John Doe Age = 25 Gender = M

和

PersonTester.jave:20: name has private access in Person
            System.out.println("p2 name = " + p2.name + "Age = " + p2.age + "Gender = " + p2.gender);

PersonTester.jave:20: age has private access in Person
            System.out.println("p2 name = " + p2.name + "Age = " + p2.age + "Gender = " + p2.gender);

PersonTester.jave:20: gender has private access in Person
            System.out.println("p2 name = " + p2.name + "Age = " + p2.age + "Gender = " + p2.gender);

3 errors

这是给定的课程

class Person {

    // Data Members 
    private String name; // The name of this person
    private int age; // The age of this person
    private char gender; // The gender of this person

    // Default constructor
    public Person() {
        name = "Not Given";
        age = 0;
        gender = 'U';
    }

    // Constructs a new Person with passed name, age, and gender parameters.
    public Person(String personName, int personAge, char personGender) {
    name = personName;
    age = personAge;
    gender = personGender; 
    } 

    // Returns the age of this person.
    public int getAge( ) {
        return age;
    }

    // Returns the gender of this person.
    public char getGender( ) {
        return gender;
    }

    // Returns the name of this person.
    public String getName( ) {
        return name;
    }

    // Sets the age of this person.
    public void setAge( int personAge ) {
        age = personAge;
     }

    // Sets the gender of this person.
    public void setGender(char personGender) {
        gender = gender;
    }

    // Sets the name of this person.
    public void setName( String personName ) {
        name = personName;
    }

} // end class

这就是我所做的

import java.util.Scanner;

public class Person_Tester { 

static char gender;

    public static void main(String [] args){ 

        //Create Array
        Person[] p1 = new Person[2]; 
        Person[] p2 = new Person[1];

      try(Scanner string_input = new Scanner(System.in); 
         Scanner int_input = new Scanner(System.in)) {

        for (int i = 0; i < 3; i++) { 

            Person person1 = new Person(); 

            Person person2 = new Person();

            //Enter Details For Person1

            System.out.println("Name: "); 

            person1.setName(string_input.nextLine()); 

            System.out.println("Age: "); 

            person1.setAge(string_input.nextInt()); 

            System.out.println("Gender: "); 

            gender = string_input.next().charAt(0);

            System.out.println(); 

            //Enter Details For Person2 

            System.out.println("Name: "); 

            person2.setName(string_input.nextLine()); 

            System.out.println("Age: "); 

            person2.setAge(string_input.nextInt()); 

            System.out.println("Gender: "); 

            gender = string_input.next().charAt(0);  

            System.out.println(); 

            string_input.close();
            int_input.close();

        }

      }//end for loop 

    }//end main method

}//end class

很抱歉最后一次写错了我的问题

当我运行代码时，这就是我得到的

Name: 
John Doe
Age: 
22
Gender: 
M

Name: 
Age: 
21
Gender: 
F

Exception in thread "main" java.lang.IllegalStateException: Scanner closed
    at java.util.Scanner.ensureOpen(Unknown Source)
    at java.util.Scanner.findWithinHorizon(Unknown Source)
    at java.util.Scanner.nextLine(Unknown Source)
    at Person_Tester.main(Person_Tester.java:26)
Name:

我试过拿出

string_input.close();
int_input.close();

我得到了

Name: 
john doe
Age: 
22
Gender: 
m

Name: 
Age: 
21
Gender: 
f

Name: 
Age: 
21
Gender: 
f

Name: 
Age: 
23
Gender: 
m

Name: 
Age:

它一直在运行，不让我输入名字

请帮我修理一下，我需要在下午1点之前完成它

Answer 1

错误消息正确，因为Scanner对象实际上没有nextAt()方法。它有.next()，.nextInt()，.nextLine()，.nextDouble()，......但没有.nextAt()。这里的关键是当你遇到类似的问题时，检查Java API以查看可用的方法。这是Scanner API部分的链接，它将显示扫描程序对象可用的所有方法/构造函数。

编译器非常严格且不可原谅，不允许使用伪造的方法，因此编码人员也必须严格执行。

Java程序类和测试程序

1 个答案: