Android中浅拷贝与深拷贝

private ResponseImpl wrapper;

public ResponseImpl getWrapper() {
return wrapper;
}

public void setWrapper(ResponseImpl wrapper) {
this.wrapper = wrapper;
}

@NonNull
@Override
protected Object clone() throws CloneNotSupportedException {
Response response = (Response) super.clone();
return response;
}
}

在这里我们创建了一个Response类，实现了Cloneable接口并重写了clone方法。Response类内部有一个属性为ResponseImpl类，该类并没有实现Cloneable接口。我们看一下运行结果：

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
response1=new Response();
response1.name=“yydm”;
response1.age=10;

ResponseImpl wrapper=new ResponseImpl();
wrapper.height=172;
response1.setWrapper(wrapper);

try {
response2= (Response) response1.clone();
} catch (CloneNotSupportedException e) {
e.printStackTrace();
}
}
public void start(View view) {

Log.i(“MDY”, “name=”+response1.name+" age=“+response1.age);
Log.i(“MDY”, “name-hashcode=”+response1.name.hashCode()+” wrapper-hashcode="+response1.getWrapper().hashCode());

Log.i(“MDY”, “start------------”);
Log.i(“MDY”, “name=”+response2.name+" age=“+response2.age);
Log.i(“MDY”, “name-hashcode=”+response2.name.hashCode()+” wrapper-hashcode="+response2.getWrapper().hashCode());

}

结果：
2020-01-02 22:47:49.988 20574-20574/com.mdy.rp I/MDY: name=yydm age=10
2020-01-02 22:47:49.989 20574-20574/com.mdy.rp I/MDY: name-hashcode=836268084 wrapper-hashcode=223567989
2020-01-02 22:47:49.989 20574-20574/com.mdy.rp I/MDY: start------------
2020-01-02 22:47:49.989 20574-20574/com.mdy.rp I/MDY: name=yydm age=10
2020-01-02 22:47:49.989 20574-20574/com.mdy.rp I/MDY: name-hashcode=836268084 wrapper-hashcode=223567989

可以看到 wrapper对象的hashcode是相等的，因此clone的对象response2的wrapper属性 clone的是对象引用。

深拷贝

深拷贝和浅拷贝的不同之处在于，源对象中的对象属性在被拷贝时，会根据源对象属性的内存大小划分一块内存空间，并根据源属性的值创建一个新的属性。例如以下：

public class Response implements Cloneable{

public String name;
public int age;

private ResponseImpl wrapper;

public ResponseImpl getWrapper() {
return wrapper;
}

public void setWrapper(ResponseImpl wrapper) {
this.wrapper = wrapper;
}

@NonNull
@Override
protected Object clone() throws CloneNotSupportedException {
Response response = (Response) super.clone();
response.wrapper= (ResponseImpl) wrapper.clone();
return response;
}
}

public class ResponseImpl implements Cloneable{

public long height;

@NonNull
@Override
protected Object clone() throws CloneNotSupportedException {
return super.clone();
}
}
可以看到首先在属性对象的类中实现Cloneable接口，并重写clone方法。然后在Response的clone函数中分别实现自身的clone方法和属性对象的clone方法。看一下运行结果：
2020-01-02 22:54:49.543 20784-20784/com.mdy.rp I/MDY: name=yydm age=10
2020-01-02 22:54:49.543 20784-20784/com.mdy.rp I/MDY: name-hashcode=836268084 wrapper-hashcode=223567989
2020-01-02 22:54:49.543 20784-20784/com.mdy.rp I/MDY: start------------
2020-01-02 22:54:49.543 20784-20784/com.mdy.rp I/MDY: name=yydm age=10
2020-01-02 22:54:49.543 20784-20784/com.mdy.rp I/MDY: name-hashcode=836268084 wrapper-hashcode=56748042
可以看到wrapper的hashcode值不相同，表明是两个对象了。