Users are required to enter the correct passcode to start the application. The s

Question

Users are required to enter the correct passcode to start the application. The system uses a scramble keypad with a randomly allocated set of numbers from 0 to 9. The display shall show "Enter passcode" initially, and show an asterisk (*) for each number entered. Upon pushing the "Enter" button, the system verifies the passcode. If the passcode is correct, the system invokes a method called startApp() to start the application. Otherwise, it displays "Wrong passcode". The "Clear" button shall clear the display. Assume that the following methods are available:

// return the passcode

public String getPasscode(){

//Random rnd = new Random();

//String passcode4digit = rnd.nextInt(10) + “” + rnd.nextInt(10) + “” + // rnd.nextInt(10) + “” + rnd.nextInt(10);

String passcode4digit =”7312”;

return passcode4digit;

}

// Start the application public void startApp(){

System.out.println(“Application started”); }

// Shuffle (Randomize) the given int array, e.g.,

// int[] numbers = {1, 2, 3, 4, 5};

// shuffleArray(numbers);

// randomize the elements

public void shuffleArray(int[] ar)

{

Random rnd = new Random();

for (int i = ar.length - 1; i > 0; i--) {

int index = rnd.nextInt(i + 1);

// Simple swap

int a = ar[index];

ar[index] = ar[i];

ar[i] = a;

}

}

Explanation / Answer

Okay so for this lets write main:

// This is a password masking based Authentication

// start a thread that wuld make asterisk appear in the password field.

// make other thins work as usual

//To get the value of password, use:

// String.valueOf(password);

PSB code snippet:

import java.io.*;

public class PwdMask {
public static void main(String[] args) {
char password[] = null;
try {
passcode = PasscodeClass.retreive(System.in, "Enter passcode: ");
} catch(IOException io) {
io.printStackTrace();
}
if(String.valueOf(password)=="passcode") // define your own and act acoordingly
{

}
}
}
}

---Now Passcode.class whih would implement ther class thread----

public class PasswordField {

public static final char[] getPassword(InputStream in, String message) throws IOException {
PutAsterik ast = new PutAsterisk(message);
Thread thread = new Thread(ast);
thread.start(); // for printing asterisks
//...print messgae and do comparing
//stop masking here
}
}
  
---------------------PutAsterisk class--------------
class PutAsterisk extends Thread {

public PutAsterisk(String msg) {
System.out.print(msg);
}

public void run() {
Thread.currentThread().setPriority(Thread.MAX_PRIORITY);
try {

while(stop) {
System.out.print("*");
try {
Thread.currentThread().sleep(1);//for producing delay
}catch (InterruptedException iex) {
Thread.currentThread().interrupt();
return;
}
}
} finally {
Thread.currentThread().setPriority(priority);
}
}

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