我如何在Java中的不同类中使用相同的对象 [英] How can i use same object in different classes in Java

问题描述

假设我有3个java类A，B和C

Suppose i have 3 java classes A , B and C

我需要创建一个在A和B中都使用的C类对象但是问题在单独创建对象是类c的构造函数被调用2次。但是我想要只调用一次构造函数。

I need to create an object of class C that is used in both A and B but the problem in creating the object separately is that the constructor of class c is called 2 times. But i want the constructor to be called just once.

所以我想将类A中创建的对象用于b类。

So i want to use the object created in class A into class b.

推荐答案

所以创建一次对象，并将其传递给A和B的构造函数：

So create the object once, and pass it into the constructors of A and B:

C c = new C();
A a = new A(c);
B b = new B(c);

...

public class A 
{
    private final C c;

    public A(C c)
    {
        this.c = c;
    }
}

请注意，这是非常在Java中常见的一种形式的依赖注入，这样就可以告诉对象他们的协作者而不是自己构建它们。

Note that this is very common in Java as a form of dependency injection such that objects are told about their collaborators rather than constructing them themselves.

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