If I run,
String s1="abc";
then are there any differences between:
String s2=new String(s1);
and
String s2="abc";
Here's what I'm confused about:
The Head First Java says:"If there's already a String in the String pool with the same value, the JVM doesn't create a duplicate, it simply refers your reference variable to the existing entry. " Which at my point of view is that the s1 has already created "abc",s2 just refers to it. Am I right??
When you write String s2="abc";
and "abc"
is already in the pool, then you won't get a duplicate - you'll get a reference to the existing String
.
But if you write new String(something)
, you get a new String
, whether there's a matching String
in the pool or not.
String Constant Pool comes into picture in this case as shown in below screenshot.
I think it will help you to understand it visually.
String s1="abc"; // s1 will go to String constant pool
String s2=new String(s1); // any object created by "new" keyword will go to Heap
String s2="abc"; // s1 and s2 both will refer to same string in constant pool
new关键字将强制在堆中创建一个新的字符串对象,即使它已经存在于字符串池中
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