Java string operator "+"

This operator has a special purpose in Java: Connect different strings. This has been shown in the previous example. Although not consistent with the traditional meaning of +, it is still very natural to do it with +. In C + +, this feature looks very good, so introduces an "operator overload" mechanism so that C + + programmers add special meaning to almost all operators. Unfortunately, with other restrictions in C + +, operator overloading becomes a very complex feature that programmers must consider carefully when designing their own classes. Although operator overloading is easier to implement in Java than C + +, this feature is still considered too complex to date. So Java programmers can't design their overload operators as C + + programmers do.
We have noticed some interesting phenomena when using "String +". If the expression begins with a string, all subsequent operations must be strings. As shown below:

int x = 0, y = 1, z = 2;
String sstring = "x, y, z";
SYSTEM.OUT.PRINTLN (sstring + x + y + z);

Here, the Java compiler converts x,y and z into their string forms, rather than adding them together first. However, if you use the following statement:

SYSTEM.OUT.PRINTLN (x + sstring);

Then earlier versions of Java will be prompted for errors (later versions can convert x to a string). Therefore, if you want to use the "plus" connection string (using earlier versions of Java), make sure that the first element is a string (or a series of characters with quotation marks that the compilation can recognize as a string).