Question

What is the difference between these two statements?

String str = "stackoverflow";

&

String str = new String("stackoverflow");

Answer 1

It differs in how the string is taken from pool.

1.
When you say,

String str = "stackoverflow"

It will first check if "stackoverflow" already exists in String pool. If it does, then it will use the same from pool.

This is the reason why when,

String str1= "stackoverflow";
String str2 ="stackoverflow";

str1==str2? --> will be true

The result of above will be true, because same String object from pool is used.

2.
When you do,

String str = new String("stackoverflow");

Always, a new String object is created, irrespective of a same one already exists in pool or not.

So,

String str1= "stackoverflow";
String str2 =new String("stackoverflow");
String str3 =new String("stackoverflow");

Here, str2 and str3 will again create a new String object.

so, str2, str3 and str1 all refer to different objetcts and str2!=str3!=str1