JAVA中的拷貝分為淺拷貝和深拷貝兩種，從名字上已經可以看出它們的區別：淺拷貝僅僅拷貝對象的引用，而不是對象本身，而深拷貝則是在內存中重新建立一個對象副本，與原對象無關。接下來我們分別看一下如何實現淺拷貝和深拷貝。

1. 實現淺拷貝

public class ShallowCopy implements Cloneable {
private int[] data;
public ShallowCopy(int[] data) {
this.data = data;
}
public int[] getData() {
return data;
}
public Object clone() throws CloneNotSupportedException {
return super.clone();
}
}
public class Main {
public static void main(String[] args) throws CloneNotSupportedException {
int[] orig = {1, 2, 3, 4, 5};
ShallowCopy sc = new ShallowCopy(orig);
ShallowCopy sc1 = (ShallowCopy) sc.clone();
System.out.println(Arrays.toString(sc.getData()));
System.out.println(Arrays.toString(sc1.getData()));
orig[0] = 100;
System.out.println(Arrays.toString(sc.getData()));
System.out.println(Arrays.toString(sc1.getData()));
}
}

2. 實現深拷貝

public class DeepCopy implements Cloneable {
private int[] data;
public DeepCopy(int[] data) {
this.data = new int[data.length];
System.arraycopy(data, 0, this.data, 0, data.length);
}
public int[] getData() {
return data;
}
public Object clone() throws CloneNotSupportedException {
DeepCopy copy = (DeepCopy) super.clone();
copy.data = new int[this.data.length];
System.arraycopy(this.data, 0, copy.data, 0, this.data.length);
return copy;
}
}
public class Main {
public static void main(String[] args) throws CloneNotSupportedException {
int[] orig = {1, 2, 3, 4, 5};
DeepCopy dc = new DeepCopy(orig);
DeepCopy dc1 = (DeepCopy) dc.clone();
System.out.println(Arrays.toString(dc.getData()));
System.out.println(Arrays.toString(dc1.getData()));
orig[0] = 100;
System.out.println(Arrays.toString(dc.getData()));
System.out.println(Arrays.toString(dc1.getData()));
}
}

通過上面的代碼我們可以看出，淺拷貝只是賦予對象一個新的引用地址，也就是說一個對象的改變會影響到另一個對象的值，而深拷貝則是在內存中新開辟一塊區域，重新為對象分配空間，兩者的區別在于深拷貝重新分配的空間與原對象無關，對原對象的改變不會影響到深拷貝對象的值。