Why it is wrong when the number is 121

Question

This are the codes to show it is a prime number or not.i don't know if i enter 121,it get wrong result.
//Java core packages
import java.awt.*;
//Java extension packages
import javax.swing.*;
public class P3 extends JApplet {
//initialize the mod result
int result = 0, //result after mod
ponumber, //number to loop
input; //the number to be mod
//initialize applet by obtaining valuse from user
public void init()
String number;
//get number
number = JOptionPane.showInputDialog( " Please enter number to confirm " );
//convert it to integer
input = Integer.parseInt( number );
}//end first method
//draw the result
public void paint( Graphics g )
for ( ponumber = input -1;ponumber >= 2;ponumber--) //begin loop
result = input % ponumber;
//if the number is 2,its result also 0,but 2 is a prime number
//so the input number should out of 2
if (( result == 0 )&&( input > 2))
g.drawString( " Number " + input + " is not a prime number ", 25, 25 );
else
g.drawString( " Number " + input + " is a prime number ", 25,25 );
}//end second method
} //end P3 class

Answer 1

It seems to me that your answer will always be that it is a prime number.
try somthing like this:
boolean prime = true;
for(ponumber = input-1;ponumber >=2;ponumber--)
if(input%ponumber!=0) prime = false;
if(prime)
//print prime
else:
//print not primeI haven't tested this, no time now, but there is a little difference between what I have and what you have. Try to see what that is and see if this works for you. I'll check back later.