String

Strings are constants and cannot be changed after creation.

String literals are stored in the string pool and can be shared.

The case list is as follows.

1. String literals are stored in the string pool. The memory map is as follows.

2. Immutability: Change the value of name to "Zhang San", instead of directly changing "hello" to "Zhang San" in the memory, but to re-create "Zhang San" in the string pool,name changed from pointing to "hello" to pointing to "Zhang San"

3. Add a new variable name2, the value is "Zhang San", then name2 will go to the string pool to find out whether there is "Zhang San", and if so, assign "Zhang San" to name2, so thatConstant sharing is achieved.

Another way to create strings.

In this way, a "string Java" is created in the heap, and then see if there is "java" in the string pool, if not, create one.At this point the address of the variable str is the address of "Java" in the heap.

Think about it, if you use this method to create a str2 with the value "java", then str == str2?The answer is not the same, creating an object will open up a new space in the heap, and the address given to str2 is different from the address of str.