You should know more about java.lang.Math.max:
java.lang.Math.max(arg1,arg2) only accepts 2 arguments but you are
writing 3 arguments in your code.double,int,long and float but your are
writing String arguments in Math.max function. You need to parse them in the required type.You code will produce compile time error because of above mismatches.
Try following updated code, that will solve your purpose:
import java.lang.Math;
import java.util.Scanner;
public class max {
public static void main(String[] args) {
Scanner keyboard = new Scanner(System.in);
System.out.println("Please input 3 integers: ");
int x = Integer.parseInt(keyboard.nextLine());
int y = Integer.parseInt(keyboard.nextLine());
int z = Integer.parseInt(keyboard.nextLine());
int max = Math.max(x,y);
if(max>y){ //suppose x is max then compare x with z to find max number
max = Math.max(x,z);
}
else{ //if y is max then compare y with z to find max number
max = Math.max(y,z);
}
System.out.println("The max of three is: " + max);
}
}