如何在Java中为不同的类创建不同的包？

class Human
{
// Properties --> Instance variables
String name;
int age;
// Actions --> methods
void speak()
{
System.out.println("Hey there! I am " + name);
System.out.println("My age is " + age);
}
}


Hey there! I am Vasanth Kumar
My age is 20


import java.io.*;


java.lang
java.util
java.io
java.awt
java.net
java.applet
java.text
java.sql
javax.swing


package package_name ;


package package_name.subpackagename ;


C:\> javac -d . classname.java


C:\> java packagename.classname


Enter the number of students : 2
Enter the details of Student 1 (id, name, location):
B200 Ajay Hyderabad
Enter the details of Student 2 (id, name, location):
B100 Ramesh Hyderabad


The Student Details are:
B100 Ramesh Hyderabad
B200 Ajay Hyderabad


// Java Program Illustrating Dividion of Classes into
// Packages where Class StudentData
// which creates first package i.e pack1
// Importing package
package pack1;
// Main class
public class StudentData {
    private String id;
    private String name;
    // Method 1
    public void addStudentData(String id, String name)
    {
        // This keyword refers to current instance itself
        this.id = id;
        this.name = name;
    }
    // Getter setters Methods
    // Use getter methods so that we can
    // access private members for other packages
    public String getId() { return id; }
    public String getName() { return name; }
}


// Java Program Illustrating Dividion of Classes into
// Packages where Class StudentDataExtended creates
// Second package- pack2 and uses the first package
// Importing packages
package pack2;
// Importing required classes
// from pre-defined packages
import java.io.*;
import java.lang.*;
import java.util.*;
import pack1.*;
// Main class
class StudentDataExtended extends StudentData {
    private String location;
    public void addDetails(String id, String name,
                           String location)
    {
        addStudentData(id, name);
        // This keyword refers to current object itself
        this.location = location;
    }
    // Method 1
    public static void
    printDetails(TreeMap<String, StudentDataExtended> map)
    {
        // Iterating via for each loop
        for (String a : map.keySet()) {
            StudentDataExtended student = map.get(a);
            // Print ID and name of student
            System.out.println(student.getId() + " "
                               + student.getName() + " "
                               + student.location);
        }
    }
    // Method 2
    // Main driver method
    public static void main(String[] args)
    {
        // Display a message for asking input from the user
        System.out.print("Enter the number of students : ");
        // Scanner class to read user input
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        String buffer = sc.nextLine();
        int count = 1;
        // Creating a TreeMap
        TreeMap<String, StudentDataExtended> map
            = new TreeMap<>();
        while (n != 0) {
            System.out.println(
                "Enter the details of Student " + count
                + " (id, name, location):");
            count++;
            String details = sc.nextLine();
            String studentInfo[] = details.split(" ");
            StudentDataExtended student
                = new StudentDataExtended();
            student.addDetails(studentInfo[0],
                               studentInfo[1],
                               studentInfo[2]);
            map.put(studentInfo[0], student);
            n--;
        }
        // Display message
        System.out.println("\nThe Student Details are:");
        // Calling above method 1 to
        // print details of the students
        printDetails(map);
    }
}