Min Heap using java with build heap , delete by passing postion of the element to be deleted and insertion of an element.

MaxHeap.java

import java.util.*;
import java.lang.Math;

public class MaxHeap {
    ArrayList<Integer> ar = new ArrayList<>();
    int size = 0;
    
    void delete(int pos)
    {
        ar.set(pos,ar.get(ar.size()-1));
        ar.remove(ar.size()-1);
        heapify(pos);
        
    }
    
    void insert(int val)
    {
        int i = ar.size();
        ar.add(val);
        int parent = i -1;
        while(parent > 0)
        {
            parent = (int)Math.ceil((float)i/2 - 1);
            if(ar.get(i) < ar.get(parent))
            {
                int temp = ar.get(parent);
                ar.set(parent,ar.get(i));
                ar.set(i,temp);
                i = parent;
            }
            else break;
        }
        heapify(i);
    }
    
    void heapify(int i)
    {

        int size = ar.size()/2;
        int parent=0;
        int lchild=0;
        int rchild = 0;
        while(i < size)
        {
            lchild = 2*i+1;
            rchild = 2*i+2;
            parent = i;
            
            if(rchild < ar.size() && ar.get(rchild) < ar.get(i))
            i = rchild;
            
            if(ar.get(lchild) < ar.get(i))
            i = lchild;
            
            if(i==parent)break;
            
            int temp = ar.get(parent);
            ar.set(parent,ar.get(i));
            ar.set(i,temp);
            
        }
    }
    
    void buildHeap()
    {
        int n = ar.size()/2;
        while(n > 0)
        {
            
            heapify(--n);
            
        }
    }
    
    
    void print()
    {
        for(int x : ar)
        System.out.print(x+"  ");
        System.out.println();
    }
    
    public static void main(String args[])
    {

        Scanner sc = new Scanner(System.in);
        MinHeap mh = new MinHeap();
        while(sc.hasNextInt())
        {
            mh.ar.add(sc.nextInt());
        }
        mh.buildHeap();
        mh.print();
        mh.insert(-1);
        mh.print();
        mh.delete(1);
        mh.print();
        mh.insert(0);
        mh.print();
        
    }
}

Please comment if at all you get any doubt(s)