The difference between using string constants to assign values in Java and constructing a string object with new

" ABC "  New String ("ABC");

String str1 = "abc"; it is possible to create or not create an object, and if the string "ABC" does not exist in the Java string pool, it creates a string object ("abc") in Java string dominant. Then str1 points to this memory address, regardless of how many string objects in this way are later created with values of "ABC", there is always only one memory address assigned, followed by a copy of string, called "string Dwell" in Java, and all string constants will automatically reside after compilation.

String str2 = new String ("ABC"); At least one object can be created or two. Because the new keyword is used, a str2 string object will definitely be created in the heap, whose value is "ABC". At the same time, if the string does not exist in the Java string pool, it will create the string object "ABC" in Java dominant

String str1 =NewString ("ABC"); String str2=NewString ("ABC"); str1= = STR//falseString STR3="ABC"; String STR4="ABC"; String STR5="AB"+"C"; STR3= = STR4//trueSTR3 = = STR5//trueString a="ABC"; String b="AB"; String C= B +"C"; System. out. println (A = = c);//false

A, B is determined at compile time, and C is a reference variable and is not determined at compile time.

Application: Recommended in peacetime use, try to use string = "ABCD", this way to create a string, rather than string = new string ("ABCD"), this form, because using the new constructor to create a string object will certainly open up a new heap space , while double quotes are optimized using string interning (String dwell), which is much more efficient than the constructor.

Reference: 1. The difference between string assignment in Java and use of new

The difference between the string class in 2.Java and the direct assignment string through new

The difference between using string constants to assign values in Java and constructing a string object with new