Calculate The Largest Number In The Given Array Using Java

import java.io.*; 
import java.text.*; 

class ssva21 
{ 
public static void main(String arg[]) throws IOException 
{ 
double a[]=new double [20],temp=0; 
int n; 
BufferedReader obj=new BufferedReader(new InputStreamReader(System.in)); 
System.out.println("\n BIGGEST NUMBER"); 
System.out.println(" --------------"); 
System.out.print("\nENTER HOW MANY NUMBER : "); 
n=Integer.parseInt(obj.readLine()); 
NumberFormat nf=NumberFormat.getInstance(); 
nf.setMaximumFractionDigits(2); 
nf.setMinimumFractionDigits(0); 
System.out.println("\nENTER THE NUMBERS\n"); 
for(int i=0;i<n;i++) 
{ 
a[i]=Double.parseDouble(obj.readLine()); 
} 
for(int i=0;i<n-1;i++) 
{ 
for(int j=i+1;j<n;j++) 
{ 
if(a[i]>a[j]) 
{ 
temp=a[i]; 
a[i]=a[j]; 
a[j]=temp; 
} 
} 
} 
System.out.println("\nTHE BIGGEST NUMBER IS : "+nf.format(temp)); 
System.out.println("\n"); 
} 
}