What are the differences between creating string objects using double quotes and the new String constructor?

When creating strings in Java using double quotes, for example String s = "hello";, the string literal is placed in the string pool. If such a string already exists in the pool, the variable simply references the existing object, which saves memory.

Using the constructor new String("hello") creates a new object on the heap, even if such a string already exists in the pool. This means that new String() always creates a new instance and does not reuse existing ones.

Example:

String a = "test";
String b = "test";
String c = new String("test");

System.out.println(a == b); // true, both refer to the same object in the pool
System.out.println(a == c); // false, c is a new object

Therefore, using double quotes is preferable for memory efficiency and performance.