Java 是创建对象的深层副本还是仅链接到其引用

Question

Let say I have the following code:

ArrayList<String> aList = new ArrayList<String>();
aList.add(new String("abc");
...
String aString = aList.get(0);

Does aString have a deep copy of aList.get(0), which means a new memory location with the new String object, or aString is just assigned a reference pointer to the same object as aList has in position 0?

Answer 1

没有隐式的深拷贝，引用被赋值。

Answer 2

aString holds a reference to the object created by the expression new String("abc") . It does not hold a reference to the first position of the list, so changing the list after the assignment does not change aString . Also, in Java, Strings are immutable objects, which means the value of the String itself cannot be changed.