My First Java program :-)
Code:
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
class FindPrimes extends JFrame implements Runnable, ActionListener {
Thread go;
JLabel howManyLabel = new JLabel("Quantity: ");
JTextField howMany = new JTextField("400",10);
JButton display = new JButton("Display primes");
JTextArea primes = new JTextArea(8,40);
FindPrimes() {
super("Find Prime Numbers");
setSize(400, 300);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Container content = getContentPane();
BorderLayout bord = new BorderLayout();
content.setLayout(bord);
display.addActionListener(this);
JPanel topPanel = new JPanel();
topPanel.add(howManyLabel);
topPanel.add(howMany);
topPanel.add(display);
content.add(topPanel, BorderLayout.NORTH);
primes.setLineWrap(true);
JScrollPane textPane = new JScrollPane(primes);
content.add(textPane, BorderLayout.CENTER);
setVisible(true);
}
public void actionPerformed(ActionEvent evt) {
display.setEnabled(false);
if (go ==null) {
go = new Thread(this);
go.start();
}
}
public void run() {
int quantity = Integer.parseInt(howMany.getText());
int numPrimes = 0;
//candidate: the number the number the might be prime
int candidate = 2;
primes.append("First " + quantity + " primes:");
while (numPrimes < quantity) {
if (isPrime(candidate)){
primes.append(candidate + " " );
numPrimes++;
}
candidate++;
}
}
public static boolean isPrime(int checkNumber) {
double root = Math.sqrt(checkNumber);
for (int i = 2; i <= root; i++) {
if (checkNumber % i ==0)
return false;
}
return true;
}
public static void main(String[] arguments) {
FindPrimes fp = new FindPrimes();
}
}
