Whenever we create a String literal or a String constant, Java searches its String pool and if string is found, it will give reference to the String variable. Please note this is true only when we create a literal and not the object, i.e you do String str=”hello” and not String str=new String(“hello”);

Another point of importance is that if you compare string literals using ==, it might work because as mentioned above both the Strings might be refering to same object.

Example

String str=”hello “+”kamal”;
String str1=”hello”;
str1+=” kamal”;
String str2=”hello kamal”;
String str3=”hello kamal”;

System.out.println(str);
System.out.println(str1);
System.out.println(str2);
System.out.println(str3);
// all above prints hello kamal

System.out.println(str==str1); //false
System.out.println(str==str2); //true
System.out.println(str==str3); //true
System.out.println(str.equals(str1)); //true
System.out.println(str.equals(str2)); //true
System.out.println(str.equals(str3)); //true