Question

我有一些类似UniversityDepartment＆amp; PolytechnicDepartment这两个类扩展了AcademicDepartment类。问题要我这样做。 AcademicDepartment可以有研究生课程＆amp;研究生课程。部门将是2 University＆amp; Polytechnic。根据研究生课程中的实验室数量，对于理工学院或大学的部门。因此，如果我们在研究生或研究生课程，我认为用户必须从键盘输入，如果我们在研究生，我们也必须被问到，如果我们在理工学院或大学，我们有多少实验室。那么我将如何做到这一点？我将举例说明我的代码：

import java.io.*;

public class  AcademicDepartment {
    private String names;
    private String labs;
    private int teachers;
    private int graduates;
    // private boolean studies;

    public void infostudies() throws IOException{
        System.out.println("Enter the department you want."
            + "Press 1 for pre-graduate program  or 2 for after-graduate program" );  
        String studies = "";  
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));  
        studies = br.readLine(); 

        if (studies == 1){
            System.out.println("You are in pre-graduate program");
            System.out.println("Enter the number of labs");
            String labs = ""; 
            BufferedReader br1 = new BufferedReader(new InputStreamReader(System.in));
            labs = br1.readLine();

            if (labs > 5){
                System.out.println("The department is polytechnic");
            }
        }        

        if (labs < 5 ){
            System.out.println("The department is University");
        }
        else
        {
            System.out.println("Wrong number try again");
        }
    }    

    public AcademicDepartment(String names,String labs,int teachers,int graduates){
        names = new String(names);
        this.labs = labs;
        this.teachers = teachers;
        this.graduates = graduates;
    }

    public void printdepartmentinfo(){
        System.out.println("The names are:" + names);
        System.out.println("The labs are:" + labs);
        System.out.println("The GRADUATES are:" + graduates);
        System.out.println("The teachers are:" + teachers);   
    }
}

Answer 1

关于代码，有一些不幸的事情。

一个问题是您将字符串变量studies和labs与整数文字进行比较。编译器不允许这样做。通常，可以将String变量（使用String.equals）与String文字进行比较，或者在与整数进行比较之前尝试使用Integer.parseInt解释String变量。

另一个问题是方法infostudies的一些局部变量与类AcademicDepartment的字段具有相同的名称。这是允许的，但它不必要地混淆。

举个例子，你将处理变量studies，但我会告诉你我对变量labs的意思。

不要这样做：

public class AcademicDepartment {
    ...
    public void infostudies() throws IOException {
        ...
        if (studies == 1) {
            ...
            String labs = "";
            ...
            if (labs > 5){ // Compare String with int? Won't compile!
                ...
            }
            ...
        }
        if (labs < 5) { // Can't see the "labs" defined above!
            ...
        }
        ...
    }
}

这样做：

public class AcademicDepartment {
    ...
    public void infostudies() throws IOException {
        ...
        if (studies == 1) {
            ...
            String labs = "";
            ...
            try {
                   int labCount = Integer.parseInt(labs);
                   if (labCount > 5) {
                       System.out.println("The department is polytechnic");
                   } else {
                       System.out.println("The department is University");
                   }
            } catch (NumberFormatException formatErr) {
                System.out.println("Sorry, couldn't understand your number of labs.");
            }
            ...
        }
        ...
    }
}

从System.in获取并使用所需项目的编号

1 个答案: