driver.java

Java程序设计(美) David D. Riley著 机械工业出版社 书籍配套 代码

import java.awt.TextArea;
import javax.swing.JFrame;

/** Primes Program (Figures 10.9 & 10.10) 
 *  Author: David Riley
 *  Date: January, 2005
 */
public class Driver  {
	private JFrame window;
	private TextArea outPane;
	private PrimeField inField;

	public Driver()   {
		window = new JFrame("Prime Numbers");
        window.setBounds(10, 10, 250, 250);
        window.setVisible(true);
        window.setLayout(null);
		inField = new PrimeField(10, 10, this);
        window.add( inField, 0 );
		outPane = new TextArea();
        outPane.setBounds(50, 50, 150, 180);
        window.add(outPane, 0);
		window.repaint();
	}
	
	/**	pre:	n >= 0  <br>
	 *  post:	the first n prime numbers are output in outPane 
     */
	public void displayPrimes( int n )   {
		int potentialPrime, primeCount;
		outPane.setText(" ");  // clear the pane 
		outPane.append("Primes\n");
		potentialPrime = 2;
		primeCount = 0;
		while  (primeCount != n)   {
			if ( isPrime(potentialPrime) ) {
				outPane.append("      " + potentialPrime + "\n");
				primeCount++;
			}
			potentialPrime++;
		}
	}
	
	/** pre:    n >= 2   <br>
	 *	post:   result == p is a prime number 
     */
	public boolean isPrime( int p )   {
		int divisor;
		boolean looksPrime;
		looksPrime = true;
		divisor = 2;
		while (divisor <= Math.sqrt(p))   {
			if (p/divisor == (double)p/divisor)   {
				looksPrime = false;
			}
			divisor++;
		}
		return looksPrime;
	}
}