import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.concurrent.ExecutionException;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.SwingWorker;


public class Demo1WithSwingWorker extends JFrame implements ActionListener{
	JLabel jlabe_text,jlabe_result;
	JTextField jtext_input;
	JButton jbutt_calc;
	SwingWorker<String, Void> worker;
	String theresult;
	
	
	/**
	 * Init the GUI elements
	 */
	public void initComponents(){			
		jlabe_text = new JLabel("Calculate prime:");
		jtext_input = new JTextField();
		jlabe_result = new JLabel();
		jbutt_calc = new JButton("Calc");
		jbutt_calc.addActionListener(this);
		jbutt_calc.setActionCommand("calc");
		
		getContentPane().setLayout(new GridLayout(1,4));
		getContentPane().add(jlabe_text);
		getContentPane().add(jtext_input);
		getContentPane().add(jbutt_calc);
		getContentPane().add(jlabe_result);
		
		pack();
		setSize(400,60);
		setVisible(true);
	}
	
	
	public void actionPerformed(ActionEvent evt){
		String cmd = evt.getActionCommand();
		if(cmd.equalsIgnoreCase("calc")){	// calc button pressed
			// Construct a new SwingWorker
			worker = new SwingWorker<String, Void>(){
				
				@Override
				protected String doInBackground(){
					return getXPrime(Integer.parseInt(jtext_input.getText()));
				}
				
				@Override
				protected void done(){
					try {
						jlabe_result.setText(get());
					} catch (InterruptedException e) {
						e.printStackTrace();
					} catch (ExecutionException e) {
						e.printStackTrace();
					}
				}
			};
			// Execute the SwingWorker; the GUI will not freeze
			worker.execute();
		}
	}
	
		
	public static void main(String[] args) {
		new Demo1WithSwingWorker().initComponents();
	}
	
		
	/**
	 * The time consuming method. For this example it's not important
	 * how this method works.
	 * Given a number n this method calculates the n th prime
	 * e.g. given n = 5 the 5th prime is 11
	 * @param the n th prime to be calculated
	 * @return the prime
	 */
	public String getXPrime(int n){
		int primes = 1;
		int zahl = 2;
		while(primes != n){
			zahl++;
			for(int i=2;i<zahl;i++){
				if(!(zahl%i==0) && i+1 == zahl){
					primes++;
					i = zahl+1;
				}
				else if(zahl%i==0){
					i = zahl+1;
				}					
			}			
		}
		return String.valueOf(zahl);
	}
}