如何编写构造函数来接受实例字段的输入参数？ [英] How do I write a constructor to accept input parameters for instance fields?

问题描述

以下是GymMembership类的toString（）方法。

public String toString（）

{

return会员编号：+ memberNumber

+会员名称：+会员名号

+会员类型：+ memberShipType;

}

为GymMembership类编写两个构造函数，如下所示：
$ b $b接受

memberNumber和memberName实例字段的输入参数的构造函数
$ b $b接受所有三个实例的输入参数的构造函数

字段



我尝试过：



这是我到目前为止所做的;我认为错了



公共级健身房会员

{



//实例变量

private int memberNumber = 0;

private String memberName = null;

private String memberShipType = null;



//构造函数



public GymMembership（int memberNumber，String memberName，String memberShipType）

{

memberNumber = memberNumberIn;



memberName = memberNameIn;



memberShipType = memberShipTypeIn;



}

}

The following is a toString( ) method for a GymMembership class.
public String toString( )
{
return "Member Number: " + memberNumber
+ "Member Name: " + memberName
+ " Membership Type: " + memberShipType;
}
Write two constructors for the GymMembership class as follows:
 A constructor to accept input parameters for the
memberNumber and memberName instance fields
 A constructor to accept input parameters for all three instance
fields

What I have tried:

This is what I've done so far; I think its wrong

public class GymMembership
{

//instance variables
private int memberNumber=0;
private String memberName=null;
private String memberShipType=null;

//constructor

public GymMembership(int memberNumber, String memberName, String memberShipType )
{
memberNumber=memberNumberIn;

memberName=memberNameIn;

memberShipType=memberShipTypeIn;

}
}

推荐答案

基本上有两种方式：

there are basically two ways:

public class SomeClass
{
    private int someMember;
    public SomeClass(int someMember)
    {
        this.someMember = someMember; // note the 'this' keyword denoting the constructed class
    }
}

或

or

public class SomeClass
{
    private int _someMember;
    public SomeClass(int someMember)
    {
        _someMember = someMember; // note the '_' prefix on the private member
    }
}

基本上你需要向编译器指出什么是什么。当参数名称与成员名称相同时，编译器将假设一个或另一个但不是两者。所以你需要区分，以便编译器知道想要什么。

Essentially you need to indicate to the compiler what is what. When the parameter name is the same name as the member name, then the compiler will assume one or the other but not both. So you need to differentiate in order for the compiler to know what is wanted.

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