HashTablePractice.java

package com.company;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.Map;

public class HashTablePractice {

    public static void main(String[] args) {
        Hashtable<Integer, String> mTable = new Hashtable<>();

        mTable.put(1, "computer");
        mTable.put(2, "keyboard");
        mTable.put(3, "Laptop");
        mTable.put(4, "Monitor");
        mTable.put(5, "Printer");


        System.out.println(mTable.get(3));

        mTable.put(5, "Mobile");
        System.out.println(mTable);

        System.out.println(mTable.getOrDefault(6, "Not found"));

        Map<Integer, Student> studentHashtable = new Hashtable<>();


       /* boolean m =mTable.contains(true);

        System.out.println(m);*/

        studentHashtable.put(1, new Student("Sayeed", "23"));
        studentHashtable.put(2, new Student("Sayeed", "23"));
        studentHashtable.put(3, new Student("Robin", "23"));


        for (Map.Entry<Integer, Student> mapEntry: studentHashtable.entrySet()) {

            System.out.println(mapEntry);
        }


        HashMap<Integer,String> hashMap = new HashMap<>();
        hashMap.put(34,"sdfi");
        hashMap.put(null,null);
        hashMap.put(12,null);
        hashMap.put(12,"isdf");
        hashMap.put(14,null);
        hashMap.put(166,null);
        hashMap.put(16,null);
        System.out.println(hashMap);


        HashSet<Student> mNumber = new HashSet<>();
        mNumber.add(new Student("Sayeed","23"));
        mNumber.add(new Student("Sayeed","23"));
        mNumber.add(new Student("Sayeed","23"));
        mNumber.add(new Student("Sayeed","23"));


        for (Student mValue: mNumber) {
            System.out.println(mValue);
        }
    }
}

Main.java

import java.util.ArrayList;
import java.util.Arrays;

public class Main {

    public static void main(String[] args) {
	// write your code here
        /**
         * ArrayList =  Dynamic Array
         */

        ArrayList<Integer> numbers = new ArrayList();
        ArrayList<Student> studentArrayList = new ArrayList<>();
        ArrayList<String> textList = new ArrayList<>();
        ArrayList<Boolean> booleans = new ArrayList<>();

        numbers.add(2);
        studentArrayList.add(new Student("Sayeed","23"));
        textList.add("Isdfs");
        booleans.add(true);

        numbers.add(4);
        studentArrayList.add(new Student("Bappi","23"));
        textList.add("Isdfs");
        booleans.add(true);

        numbers.add(5);
        studentArrayList.add(new Student("Masum","23"));
        textList.add("Isdfs");
        booleans.add(true);

        numbers.add(7);
        studentArrayList.add(new Student("Rafi","23"));
        textList.add("Isdfs");
        booleans.add(true);

        numbers.add(88);
        studentArrayList.add(new Student("Robin","23"));
        textList.add("Isdfs");
        booleans.add(true);

        numbers.add(9);
        studentArrayList.add(new Student("Ekanto","23"));
        textList.add("Isdfs");
        booleans.add(true);

        System.out.println(Arrays.toString(studentArrayList.toArray()));
        Student student = studentArrayList.get(2);
        System.out.println(student);
       // studentArrayList.remove(student);
        System.out.println(Arrays.toString(studentArrayList.toArray()));
        boolean isDelete = studentArrayList.remove(student);

        ArrayList<Student> mStudentList = new ArrayList<>();

        mStudentList.add(new Student("sfsfs","12"));
        mStudentList.add(new Student("sfsfs","12"));
        mStudentList.add(new Student("sfsfs","12"));
        mStudentList.add(new Student("sfsfs","12"));
        mStudentList.add(new Student("sfsfs","12"));
        studentArrayList.addAll(mStudentList);

        for (Student mStudent: studentArrayList) {
            System.out.println(mStudent);
        }

    }
}

Student.java

package com.company;

import java.util.Objects;

public class Student   {

    private String name;
    private  String age;

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

    @Override
    public String toString() {
        return "{"+ this.name+ " "+this.age+"}";
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Student student = (Student) o;
        return Objects.equals(name, student.name) &&
                Objects.equals(age, student.age);
    }

    @Override
    public int hashCode() {
        return Objects.hash(name, age);
    }
}