os :- fcfs and sjf

import java.lang.*;
import java.util.*;
class FC
{
    public static void display(int a[],int n,int wait[],int waitavg,int turnavg);
    {
        System.out.println("\nFollowing are the waiting time and waiting time average");
        int i;
        for(i=0;i<n;i++)
        {
            System.out.println("\nP"+(i+1)+"    -> "+wait[i]);
        }
        System.out.println("\nWaiting time average = "+waitavg);
        System.out.println("\nFollowing are the turn around time and turn around  time average");
        int i;
        for(i=0;i<n;i++)
        {
            System.out.println("\nP"+(i+1)+"    -> "+a[i]);
        }
        System.out.println("Waiting time average = "+turnavg);
    }
    public static void sjf()
    {
        Scanner t = new Scanner (System.in);
        System.out.println("\nEnter no. of process ");
        int n = t.nextInt();
        int a[] = new int[];
        System.out.println("\nEnter burst time ");
        int i;
        for(i=0;i<n;i++)
            a[i]=t.nextInt();


    }
    public static void fcfs()
    {
        Scanner t = new Scanner (System.in);
        System.out.println("\nEnter no. of process ");
        int n = t.nextInt();
        int a[] = new int[];
        System.out.println("\nEnter burst time ");
        int i;
        for(i=0;i<n;i++)
            a[i]=t.nextInt();
        int wait = new int[];
        int waittotal=0;
        wait[0]=0;
        for(i=1;i<n-1;i++)
        {
            wait[i] = a[i+1];
            waittotal = waittotal + wait[i];
        }
        int waitavg = waittotal/n;
        int turn = 0;
        for(i=0;i<n;i++)
            turn = turn + a[i];
        int turnavg = turn/n;
        display(a,n,wait,waitavg,turnavg);
    }
    public static void main(String args[])
    {
        Scanner t = new Scanner (System.in);
        System.out.println("Enter choice \n1.FCFS\n2.SJF ");
        int ch = t.nextInt();
        if(ch==1)
            fcfs();
        else if(ch==2)
            sjf();
        else System.out.println("Invalid choice");
    }

}