Set creation and common methods

The creation of sets and the use of methods

ArrayList<String> arr=new ArrayList<>();
        // Output set 
        System.out.println(arr);

      //public boolean add(E e);  Appends the specified element to the end of this collection 
        arr.add("yan");
        System.out.println(arr);


        //public void add(int index ,E element), Add the element in the specified position 
        arr.add(1,"fu");
        arr.add(2,"qiang");
        System.out.println(arr);

        //public boolean remove(object o) Deletes the specified element , Returns whether the deletion was successful 
        System.out.println(arr.remove("fu"));
        System.out.println(arr);

        //public E remove(int index) Delete the element where the index is made , Returns the deleted element 
        System.out.println(arr.remove(1));
        System.out.println(arr);

        //public E set(int index,E element) Modify the element at the specified index , Return the modified element 
        System.out.println(arr.set(0,"kan"));
        System.out.println(arr);

        //get(int index) Returns the element at the index 
        System.out.println(arr.get(0));

        //size(); Returns the number of elements in the collection 
        System.out.println(arr.size());

// result 
[]
[yan]
[yan, fu, qiang]
true
[yan, qiang]
qiang
[yan]
yan
[kan]
kan
1

Applications of collections

// The main function 
 // Calling method 
  public static void main(String[] args) {
    
        addStudent(array);
        addStudent(array);
        addStudent(array);
        arr(array);
        }
// How to input students' information ( Method area )
    public static void addStudent(ArrayList<Student> array){
    
        Scanner sc=new Scanner(System.in);
        // Enter student data 
        System.out.println(" Please enter the student's name ");
        String name=sc.nextLine();
        System.out.println(" Please enter the age of the student ");
        int age=sc.nextInt();
        // Create student objects   Assign the data entered by the keyboard to the student object 1
        Student s=new Student();
        s.setName(name);
        s.setAge(age);
        // Add a student object to the collection 
        array.add(s);
    }
    // The method of traversing this set 
    public static void arr(ArrayList<Student> array){
    
        for (int i = 0; i < array.size(); i++) {
    
            Student s = array.get(i);
            System.out.println(s.getName()+s.getAge());
        }
    }

Creation of student class

public class Student {
    
    private String name;
    private int age;

    public Student(String name, int age) {
    
     this.name=name;
   this.age=age;
    }

    public Student() {
    
    }

    public String getName() {
    
        return name;
    }

    public void setName(String name) {
    
        this.name = name;
    }

    public int getAge() {
    
        return age;
    }

    public void setAge(int age) {
    
        this.age = age;
    }

Three ways to traverse a set

// iterator , Collection specific traversal methods （ You can use it ）
        Iterator<Student> it= list.iterator();
        while (it.hasNext()){
    
            Student s=it.next();
            System.out.println(s.getName()+s.getAge());
        }

        // Ordinary for Traverse （ Use index ）
        for (int i = 0; i < list.size(); i++) {
    
            Student s = list.get(i);
            System.out.println(s.getName()+s.getAge());
        }

        // enhance for Ergodic set （ Commonly used ）
        for(Student s:list){
    
            System.out.println(s.getName()+s.getAge());
        }