Java进口是否专业使用？

Question

I'm currently self studying Java, and am not sure with this "import" thing. It adds classes(not sure), and has methods that would serve a different function relative on the type of class I declare from the "import"ed thing.

I'm curious if import is frequently used for work, or is this relative to the user if he/she would want to use import or not.

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner ThisObject = new Scanner(System.in);
    }
    }

Answer 1

Java import is a compile time feature that allows you to omit the package name when programming. There is no byte-code import , the compiler will replace

Scanner ThisObject = new Scanner(System.in);

with

java.util.Scanner ThisObject = new java.util.Scanner(System.in);

As for how common it is, I would say extremely . However, there is another form of import called static import which allows you to bring static methods and fields from another class into your current namespace . static import is not very common . Finally, Java variable names start with a lower case letter (by convention).

import static java.lang.System.in;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner thisObject = new Scanner(in); // System.in through static import
    }
}