Java Program for Merge intervals

import java.util.Arrays;
import java.util.Comparator;
import java.util.Stack;
public class Main {

public static void mergeIntervals(Interval arr[])
{
// Test if the given set has at least one interval
if (arr.length <= 0)
return;

// Create an empty stack of intervals
Stack<Interval> stack=new Stack<>();

// sort the intervals in increasing order of start time
Arrays.sort(arr,new Comparator<Interval>(){
public int compare(Interval i1,Interval i2)
{
return i1.start-i2.start;
}
});

// push the first interval to stack
stack.push(arr[0]);

// Start from the next interval and merge if necessary
for (int i = 1 ; i < arr.length; i++)
{
// get interval from stack top
Interval top = stack.peek();

// if current interval is not overlapping with stack top,
// push it to the stack
if (top.end < arr[i].start)
stack.push(arr[i]);

// Otherwise update the ending time of top if ending of current
// interval is more
else if (top.end < arr[i].end)
{
top.end = arr[i].end;
stack.pop();
stack.push(top);
}
}

// Print contents of stack
System.out.print("The Merged Intervals are: ");
while (!stack.isEmpty())
{
Interval t = stack.pop();
System.out.print("["+t.start+","+t.end+"] ");
}
}

public static void main(String args[]) {
Interval arr[]=new Interval[4];
arr[0]=new Interval(6,8);
arr[1]=new Interval(1,9);
arr[2]=new Interval(2,4);
arr[3]=new Interval(4,7);
mergeIntervals(arr);
}
}

class Interval
{
int start,end;
Interval(int start, int end)
{
this.start=start;
this.end=end;
}
}