你如何在java中#include文件？

import java.util.ArrayList;

public class MyClass {
    ArrayList<String> myList = new ArrayList<>();
}

import java.util.*;

public class MyClass {
    ArrayList<String> myList = new ArrayList<>();
}

import java.util.ArrayList;
import java.util.HashMap;

public class MyClass {
    ArrayList<String> myList = new ArrayList<>();
    HashMap<String, String> myMap = new HashMap<>();
}

import java.util.ArrayList;
import java.sql.Connection;

public class MyClass {
    ArrayList<String> myList = new ArrayList<>();
    Connection myConnection = null;
}

public class MyClass {
    java.util.ArrayList<String> myList = new java.util.ArrayList<>();
}