java implement heap operation method of build heap insert delete

As shown below:

import java.util.Arrays;

// Small top heap code implementation 

public class Heap {
	//  Adjust downward, the top of the large value down, mainly used to delete and build heap ,i Represents the node index to be adjusted, n Represents the most of the heap 1 Element index 
	//  When I delete it, i is 0 When you build a pile i From the last 1 The parent of each node is adjusted forward in turn 
	public static void fixDown(int[] data, int i, int n) {
		int num = data[i];
		int son = i * 2 + 1;
		while (son <= n) {
			if (son + 1 <= n && data[son + 1] < data[son])
				son++;
			if (num < data[son])
				break;
			data[i] = data[son];
			i = son;
			son = i * 2 + 1;
		}
		data[i] = num;
	}

	//  Adjust up, small value go up , Used to increase , You don't need to set the top index to move up, of course 0
	public static void fixUp(int[] data, int n) {
		int num = data[n];
		int father = (n - 1) / 2;
		// data[father] > num Is the basic condition for entering the loop ,father Reduced to 0 It's not going to go down 
		//  when n Is equal to the 0 When, father=0 ; It goes into an infinite loop, so when n==0 , you need to get out of the loop 
		while (data[father] > num && n != 0) {
			data[n] = data[father];
			n = father;
			father = (n - 1) / 2;
		}
		data[n] = num;
	}

	//  delete ,n Represents the end of the heap 1 The index of the elements 
	public static void delete(int[] data, int n) {
		data[0] = data[n];
		data[n] = -1;
		fixDown(data, 0, n - 1);
	}

	//  increase ,i Represents the number to increase, n Represents the index of the added location, which is at the end of the heap 1 An element 
	public static void insert(int[] data, int num, int n) {
		data[n] = num;
		fixUp(data, n);
	}

	//  Building the heap ,n Represents the end of the heap to be built 1 The index of the elements 
	public static void creat(int[] data, int n) {
		for (int i = (n - 1) / 2; i >= 0; i--)
			fixDown(data, i, n);
	}

	public static void main(String[] args) {
		int[] data = { 15, 13, 1, 5, 20, 12, 8, 9, 11 };
		//  Test pile of building 
		creat(data, data.length - 1);
		System.out.println(Arrays.toString(data));
		//  Test to delete 
		delete(data, data.length - 1);
		delete(data, data.length - 2);
		System.out.println(Arrays.toString(data));
		//  Test insert 
		insert(data, 3, data.length - 2);
		System.out.println(Arrays.toString(data));

	}

}