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
str1 in diagram at top position that is inside the heap.the new keyword will force to create a new string object in heap even it already exist in string pool
String s2 = new String(s1);. You should not be writing code that depends on two string references being unequal even though the contents are equal. And if you don't, thenString s2 = s1;works just as well.