The first Java programming of mine

/* *  * Writer: Sunxin. *  Date:2017.2.28. *  Main:My first Java programming. *   *  注：对以下程序操作时需要在src根目录下创建三个不同的类分别存放。 *   *   */// The class of Counterpublic class Counter {private int number;public Counter(){number = 100;}public Counter(int n){number = n;}public void add(){number += 1;}public int getNumber() {return number;}public void setNumber(int number) {this.number = number;}}// The class of Studentpublic class Student {private int number;private String name;//Constructorpublic Student(int number,String name){this.number = number;this.name = name;}public String toString(){return "name:"+name+" number:"+number;}public boolean equals(Object ss){boolean result = false;Student temp = (Student)ss;if(this.number == temp.getNumber()){result = true;}return result;}public int getNumber() {return number;}public void setNumber(int number) {this.number = number;}public String getName() {return name;}public void setName(String name) {this.name = name;}}import java.util.Scanner;import java.util.ArrayList;public class HelloJava {public static void main(String[] args){int n;Scanner scanner = new Scanner(System.in);Counter c = new Counter(300);//c.setNumber(17);c.add();c.add();Counter c2 = new Counter(); // the default constructorSystem.out.println("c = "+c.getNumber());System.out.println("c2 = "+c2.getNumber());// create some object of the class (Student)Student s = new Student(123,"Stark");Student s2;s2 = new Student(456,"Ariye");System.out.println("Hello "+s.toString());System.out.println("Hello "+s2.toString());Student s3 = new Student(123,"Stark"); ArrayList<Student> students;students = new ArrayList<Student>();students.add(s);students.add(s2);students.remove(s3);      //find the same of id which will be removed.System.out.println(students.toString());// the  cmp of the stringString a = new String("ABD");String b = new String("ABC");if(a.equals(b)){System.out.println("a is equals to b");}else{System.out.println("a is not equals to b");}//int[] s;//s = new int[10];//for(int i = 0; i<10; i++){//s[i] = i+1;//}//for(int i = 0; i<10; i++){//System.out.println(s[i]);//}}}