Linear data types

import java.util.Scanner;

public class Main {

    static Scanner sc = new Scanner(System.in);

    static public void Linear(){

        boolean a=true;
        while(a) {
            System.out.println("1.List\n2.Stack\n3.Queue\n4.Deque\n");
            int answer = sc.nextInt();
            switch (answer) {

                case 1: {
                    List ls = new List();
                    boolean q1 = true;
                    while (q1) {

                        System.out.println("1.Insert\n2.Delete\n3.Lookup\n4.Prev\n5.Next\n6.Exit");

                        int answ = sc.nextInt();
                        switch (answ) {
                            case 1: {
                                int index = sc.nextInt();
                                int data = sc.nextInt();
                                ls.Insert(index,data);
                                break;
                            }

                            case 2: {
                                int index = sc.nextInt();
                                ls.Delete(index);
                                break;
                            }

                            case 3: {
                                int pos = sc.nextInt();
                                System.out.println(ls.Lookup(pos));
                                break;
                            }

                            case 4: {
                                ls.Prev();
                                break;
                            }

                            case 5: {
                                ls.Next();
                                break;
                            }

                            case 6:{
                                q1=false;
                                Linear();
                                break;
                            }

                            default: {
                                System.out.println("Choose right item from list!");
                                break;
                            }
                        }
                    }
                }

                case 2: {
                    Stack st = new Stack();
                    boolean q2 = true;
                    while (q2) {
                        System.out.println("1.Push\n2.Pop\n3.Top\n4.Exit\n");
                        int answ = sc.nextInt();
                        switch (answ) {
                            case 1: {
                                int data = sc.nextInt();
                                st.Push(data);
                                break;
                            }

                            case 2: {
                                st.Pop();
                                break;
                            }

                            case 3: {
                                st.Top();
                                break;
                            }

                            case 4:{
                                q2=false;
                                Linear();
                                break;
                            }

                            default: {
                                System.out.println("Choose right item from list!");
                                break;
                            }

                        }
                    }
                }

                case 3: {

                    Queue qu = new Queue();
                    boolean q3 = true;
                    while (q3) {
                        System.out.println("1.Enqueue\n2.Dequeue\n3.Front\n4.Exit\n");
                        int answ = sc.nextInt();
                        switch (answ) {
                            case 1: {
                                int data = sc.nextInt();
                                qu.Enqueue(data);
                                break;
                            }

                            case 2: {
                                qu.Dequeue();
                                break;
                            }

                            case 3: {
                                qu.Front();
                                break;
                            }

                            case 4:{
                                q3=false;
                                Linear();
                                break;
                            }

                            default: {
                                System.out.println("Choose right item from list!");
                                break;
                            }
                        }
                    }
                }

                case 4: {

                    Deque de = new Deque();
                    boolean q4 = true;
                    while (q4) {
                        System.out.println("1.PushBack\n2.PushFront\n3.PopFront\n4.PopBack\n5.Front\n6.Back\n7.Print\n8.Exit\n");
                        int answ = sc.nextInt();
                        switch (answ) {
                            case 1: {
                                int data = sc.nextInt();
                                de.PushBack(data);
                                break;
                            }

                            case 2: {
                                int data = sc.nextInt();
                                de.PushFront(data);
                                break;
                            }

                            case 3: {
                                de.PopFront();
                                break;
                            }

                            case 4:{
                                de.PopBack();
                                break;
                            }

                            case 5:{
                                de.Front();
                                break;
                            }

                            case 6:{
                                de.Back();
                                break;
                            }

                            case 7:{
                                de.Print();
                                break;
                            }

                            case 8:{
                                q4=false;
                                Linear();
                                break;
                            }

                            default: {
                                System.out.println("Choose right item from list!");
                                break;
                            }

                        }
                    }


                }

                case 5: {
                    a=false;
                    break;
                }

                default: {
                    System.out.println("Choose right item from list!");
                    break;
                }
            }
        }
    }


    public static void main(String[] args) {
        Linear();
    }
}



public class List {
    private int index = 0;
    private int size = 0;
    private int[] array = new int[5];

    public void Insert(int pos, int data){

        if((pos<=size)&&(pos>=0)){
            for(int i=array.length-1; i>pos; i--)
                array[i]=array[i-1];
            array[pos]=data;
            size++;

            if(size==array.length) {
                int[] tmp = new int[array.length + 1];
                for (int i = 0; i < array.length; i++)
                    tmp[i] = array[i];
                array = tmp;
            }
        }
        else System.out.println("Error!");

    }


    public void Delete(int pos) {
        if ((pos < size) && (pos >= 0)) {
            for (int i = pos; i < size - 1; i++)
                array[i] = array[i + 1];
            size--;
        } else System.out.println("Error!");
    }


    public int Lookup(int position){
        if(size==0) {
            System.out.println("No items found!");
            return 0;
        }
        else if((position < 0 )||(position>array.length)) {
            System.out.println("Error!");
            return 0;
        }
        return array[position];
    }

    public void Prev(){
        if(index==0){
            System.out.println("Out of List range!");
            return;
        }
        System.out.println(array[index]);
        index--;
    }

    public void Next(){
        if(index==this.array.length){
            System.out.println("Out of List range!");
            return;
        }
        System.out.println(array[index]);
        index++;
    }
}

public class Stack {

    private int size = 0;
    private int[] array = new int[5];

    public void Push(int data) {
        if (size == array.length) {
            int[] tmp = new int[array.length + 1];
            for (int i = 0; i < array.length; i++) {
                tmp[i] = array[i];
            }
            array = tmp;
        }
        array[size] = data;
        size++;
    }

    public void Pop() {
        int[] arr = new int[this.array.length];
        if (size == 0) {
            System.out.println("ERROR! (items in stack is not found)");
            System.out.println();
            return;
        }
        System.out.println(array[size - 1]);
        size--;
        for (int i = 0; i < size; i++) {
            arr[i] = array[i];
        }
        array = arr;
    }

    public void Top() {

        if (size == 0) {
            System.out.println("No items found");
            System.out.println();
            return;
        }
        System.out.println(array[size - 1]);

    }
}

public class Queue {

    private int size = 0;
    private int[] array = new int[5];

    public void Enqueue(int data) {
        if (size == array.length) {
            int[] tmp = new int[array.length + 1];
            for (int i = 0; i < size; i++) {
                tmp[i] = array[i];
            }
            array = tmp;
        }
        array[size] = data;
        size++;
    }

    public void Dequeue() {
        int[] arr = new int[this.array.length];
        if (size == 0) {
            System.out.println("ERROR! (items in queue is not found)");
            System.out.println();
            return;
        }

        System.out.println(array[0]);


        for (int i = 1; i < size; i++) {
            arr[i - 1] = array[i];
        }
        array = arr;
        size--;
    }

    public void Front() {
        if (size == 0) {
            System.out.println("No items found");
            System.out.println();
            return;
        }
        System.out.println(array[0]);
    }
}

public class Deque {

    private int[] array = new int[5];
    private int size = 0;

    public void PushBack(int data){
        if (size == array.length) {
            int[] tmp = new int[array.length + 1];
            for (int i = 0; i < array.length; i++) {
                tmp[i] = array[i];
            }
            array = tmp;
        }
        array[size] = data;
        size++;
    }

    public void PushFront(int data){
        if(size==array.length) {
            int[] tmp = new int[array.length + 1];
            for (int i = 0; i < array.length; i++)
                tmp[i] = array[i];
            array = tmp;
        }

        for(int i=array.length-1; i>0; i--)
            array[i]=array[i-1];
        array[0]=data;
        size++;



    }


    public void PopFront(){
        int[] arr = new int[this.array.length];
        if (size == 0) {
            System.out.println("ERROR! (items in Deque is not found)");
            System.out.println();
            return;
        }

        System.out.println(array[0]);


        for (int i = 1; i < size; i++) {
            arr[i - 1] = array[i];
        }
        array = arr;
        size--;
    }

    public void PopBack(){
        int[] arr = new int[this.array.length];
        if (size == 0) {
            System.out.println("ERROR! (items in Deque is not found)");
            System.out.println();
            return;
        }
        System.out.println(array[size - 1]);
        size--;
        for (int i = 0; i < size; i++) {
            arr[i] = array[i];
        }
        array = arr;
    }

    public void Front(){
        if (size == 0) {
            System.out.println("No items found");
            System.out.println();
            return;
        }
        System.out.println(array[0]);
    }

    public void Print(){
        for(int i=0;i<array.length;i++)
            System.out.println(array[i]);
    }
    public void Back(){
        if (size == 0) {
            System.out.println("No items found");
            System.out.println();
            return;
        }
        System.out.println(array[size - 1]);
    }
}