Java 与 C++ “引用”的区别

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Java中的引用行为更类似于C++中的指针。以下代码作为C++中引用行为与Java引用行为的对比。

C++

code

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#include <iostream>
using namespace std;
class Hello {
public:
    string key;
    Hello(){
        key = "Hello";
    };
    Hello(string str):key(str){

    }
};

int main() {
    Hello hello;
    Hello & helloRef = hello;
    Hello hello1("hello1");
    hello = hello1;
    cout << "hello.key : \t" << hello.key << endl;
    cout << "helloRef.key : \t" << helloRef.key << endl;
    Hello hello2("hello2");
    helloRef = hello2;
    cout << "hello.key : \t" << hello.key << endl;
    cout << "helloRef.key : \t" << helloRef.key << endl;
    return 0;
}

output

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hello.key : 	hello1
helloRef.key : 	hello1
hello.key : 	hello2
helloRef.key : 	hello2

Java

code

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package main.java;

public class TestRef {
    private static class Hello{
        String key;
        Hello(){
            key = "hello";
        }
        Hello(String str){
            key = str;
        }
    }
    public static void main(String[] args){
        Hello hello = new Hello();
        Hello helloRef = hello;
        Hello hello1 = new Hello("hello1");
        hello = hello1;
        System.out.println("hello.key : \t" + hello.key);
        System.out.println("helloRef.key : \t" + helloRef.key);
        Hello hello2 = new Hello("hello2");
        helloRef = hello2;
        System.out.println("hello.key : \t" + hello.key);
        System.out.println("helloRef.key : \t" + helloRef.key);
    }
}

output

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hello.key : 	hello1
helloRef.key : 	hello
hello.key : 	hello1
helloRef.key : 	hello2