+Rupam Shaw Precedence of operation + is higher than == in java. stackoverflow.com/questions/36528144/any-of-double-equal-text-in-output-doesnt-print-it-only-prints-output-of-bo

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"=="operator is used to compare to variable whether to check both the variable are pointing the same object or not.If pointing same Object it returns true else False. In first case without using if we are not using "new" keyword to create string the string object is stored in SCP(String Constant Pool Area). where it checks previous objects with name "youtube"(according to your example")is created or not? for str there is no object with name str so one object is created,while creating next object for str1 it checks previous object and since an object with name "youtube" is availible so reference variable str1 points to the first object without creating new object..hence it returns true. In case 2: The string with "new" keyword stores the string in heap area so for every string a new object is created.So here 2 objects are created with reference variable str2 and str3 respectively containing "youtube" as data in it.As i told "=="is used to compare to variable whether to check both the variable are pointing the same object or not.In this case both str2 and str3 are pointing different objects so it returns false. :)

1) String s_1 = "Phil"; String s_2 = "Phil"; System.out.println(s_1.equals(s_2)); // True System.out.println(s_1==s_2); // True 2) String s1 = new String("durga"); String s2 = new String("durga"); System.out.println(s1.equals(s2)); // True System.out.println(s1==s2); // False 3) StringBuffer ss1 = new StringBuffer("john"); StringBuffer ss2 = new StringBuffer("john"); System.out.println(ss1.equals(ss2)); //False System.out.println(ss1==ss2); //False Here in Scenario 1, String direct literals are stored in SCP(String Constant Pool) memory where objects are not deleted until JVM shuts down, meaning objects are not eligible for garbage collection. So, in no. 1 for .equals() method, as it's overridden in String Class of Java it does content comparison unlike .equals() method from Object class. Same content comparison happens for all Wrapper classes and Collection classes as they all override the parent Object class's .equals() method. So, (s_1.equals(s_2)) gives TRUE. Now, == checks reference comparison as it always does. As "Phil" points to the same object in SCP (s_1==s_2) also gives TRUE. Here in Scenario 2, 2 objects are created using new keyword of String type and same String value is stored in both the objects s1 and s2. As .equals() method in String class overrides the parent Object class's .equals() method to do content comparison, (s1.equals(s2)) gives TRUE. Whereas both s1 and s2 are referring to 2 different objects even thought their String value/content is the same, == checks only the address of the object if they're same or not. As they have different address allocated inside memory, (s1==s2) gives FALSE. Here in Scenario 3, StringBuffer Class doesn't override the parent Object class's .equals() method. Hence, it does reference comparison just like it's parent Object class. So, both == and .equals() in scenario 3 does reference comparison. In other words, they both compare the memory address that ss1 and ss2 objects are allocated. If they are same object location then it's True or it's False. As two different objects are created with "new" keyword so they point to two different objects. So, == and .equals() both gives FALSE.

In first case, object is created only for one time in string pool. As the object is same reference is also same. So true. In second case two different objects are created in heap area. So two different references. So false