check the first number is greater than the rest two numbers.
check the second number is greater than the rest two numbers.
else print the third number.
Java Program Largest Among Three Numbers Using if else:-
import java.util.Scanner;
public class LargestInThreeNum {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter first number");
int a = sc.nextInt();
System.out.println("Enter second number");
int b = sc.nextInt();
System.out.println("Enter third number");
int c = sc.nextInt();
System.out.print("The largest number is : ");
if((a>=b) && (a>=c)) {
System.out.println(a);}
else if(b>=a && b>=c ) {
System.out.println(b);}
else {
System.out.println(c);
}}}