CareerCup

Same issue with your code. if the wrong number is at the end of the actual string, then your code is wrong. You can just add a checker before your checking.
public class keypad
{
static boolean isValidPassword(String act, String exp)
{
if (act.length() == 0 && exp.length() == 0)
{
return true;
}
if (act.length() == 0)
return false;

char notWorkingPad = '0';
int j = 0;
for (int i = 0; i < exp.length(); i++)
{
if (j >= act.length())
{
if (notWorkingPad != exp.charAt(i))
{
return false;
}
}

if (exp.charAt(i) != act.charAt(j))
{
// get the not working pad
if (notWorkingPad == '0')
{
notWorkingPad = exp.charAt(i);

}
else
{
if (notWorkingPad != exp.charAt(i))
{
return false;
}
}
}
else
{
j++;
}
}
return true;
}

public static void main(String[] args)
{
System.out.println(isValidPassword("164", "164"));
System.out.println(isValidPassword("164", "1868888847665"));
}
}

if you check the length of two input strings would be better. if the two length is not the same, then just stop.