问题
How can this be if I can create a String, giving it a value. Then, I can simply overwrite its value like this:
String a="abc";
a="def";
How is it possible that I can change the value of a? I must be missing something here. I understand that Strings literals are used whenever creating a String object, rather than creating a new instance of String every time
Please help, thanks.
回答1:
Your not changing its value you are creating a new String. Technically your variable changes its value (memory location its pointing to) to reference a new String object but it is pointing to the new String object not the same String object.
You aren't actually changing the value of the original String object you are just referencing a new String so while the value of your variable does change you aren't actually changing the original String object...Hope that makes sense.
回答2:
String a="abc";//creating string literal object
a="def";
You are actually changing the reference of a to a new object created by the String literal "def".
String is immutable means that you cannot change the object itself, but you can change the reference to the object. Changing an object means to use its methods to change one of its fields.
来源：https://stackoverflow.com/questions/31752304/how-is-string-in-java-an-immutable-object-but-i-can-still-change-its-value-afte