Heap sorting and priority queue

Heap.java

public class Sort {
    private int[] a;
    private int n;
    private int left;
    private int right;
    private int largest;

    Sort(int[] array){
        sort(array);
    }
    Sort(int[] array, boolean queue){
        if(queue){
            this.a = array;
            buildheap(this.a);
        } else {
            sort(array);
        }
    }
    private void buildheap(int []a){
        n=a.length-1;
        for(int i=n/2;i>=0;i--){
            maxheap(a,i);
        }

    }
    private void maxheap(int[] a, int i){
        left=2*i+1;
        right=2*i+2;
        if(left <= n && a[left] > a[i]){
            largest=left;
        }
        else{
            largest=i;
        }

        if(right <= n && a[right] > a[largest]){
            largest=right;
        }
        if(largest!=i){
            swap(i,largest);
            maxheap(a, largest);
        }
    }


    private void sort(int []a0){
        a=a0;
        buildheap(a);

        for(int i=n;i>0;i--){
           swap(0, i);
            n=n-1;
            maxheap(a, 0);
        }
    }
    public int[] getResult(){
        return this.a;
    }

    public int heapMaximum(){
        return this.a[0];
    }
    public void maxHeapInsert(int key){
        increaseArray(1);
        this.a[this.a.length-1]=-999;
        heapIncraseKey(this.a.length-1,key);
    }
    private void increaseArray(int number){
        int[] newArray = new int[this.a.length+number];
        for (int i=0; i<this.a.length; i++){
            newArray[i] = this.a[i];
        }
        this.a = newArray;
    }
    public void heapIncraseKey(int i,int key){
        if(key<this.a[i]){
            System.out.println("Error");
            return;
        }
        this.a[i] = key;
       buildheap(a);
    }
    private void swap(int first, int second){
        int temp = this.a[first];
        this.a[first] = this.a[second];
        this.a[second] = temp;
    }
}