java - String assignments and output -


given following code:

string str1 = new string("hello"); string str2 = str1; string str3 = new string(str1); string str4 = str3; str4 += " world "; if (str3==str4)      system.out.println(“one”); if (str3.equals(str4))      system.out.println(“two”); if (str1==str2)      system.out.println(“three”);  if (str3.equals(str2))      system.out.println(“four”);

the output : 3 , four

i don't it.. did str3 == str4 . how can not refer same object..? str3 == str4 seem false , dont why. in addition, str3.equals(str4) return false guess has first thing dont get.

would love explanation.

because string immutable, += operator creates new instance , assignes str4. therefore str4 not equal str3.


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