What is the difference between string object and string in Java?

Writing a String string refers to that string. However, the new String ("~~") is to create a new string object.

For example,

String a = "abc"; 
String b = "abc";
System.out.println(a == b);  // true

where a and b strings are the same object.

String c = new String("abc");
String d = new String("abc");
System.out.println(c == d);  // false

where c and d refer to different objects. If possible, we recommend that you use the String string. It's easier to read and gives the compiler the opportunity to optimize code.

First of all, we need to understand Heap and the String constant pool that exists in it.

String a = new String("abc"); The above sentence creates a general object in heap and then has a ref of the object.

String b = "abc"; I understand that the above sentence is stored in the String constant pool in the heap, or if it is a string that already exists, it points to the index number of the stored array.

So, the result for a == b is false. Because it's not referring to the same object.

But a.This is true because equals(b) is the result of comparing the string itself.