displayingprimenumbers.java

输入一个数,程序将会把小于等于这个数的所有素数显示到屏幕上面.

import javax.swing.JOptionPane;
public class DisplayingPrimeNumbers{
	
	public static void main (String[] args){
		
		StackOfIntegers stack = new StackOfIntegers();
		
		String sa =JOptionPane.showInputDialog(null,"Enter the decimal number please!","Find the primes",JOptionPane.QUESTION_MESSAGE);
		int a = Integer.parseInt(sa);
		
		for (int i = 2;i<=a;i++){
			int m = 1;
			for(int j= i-1;j>= 2;j--){
				if (i%j==0)
				m=0;
			}
			if (m==1)
			stack.push(i);
			
		
		}
		
		    System.out.println("The prime numbers are:");
			while(!stack.empty())
			System.out.print (stack.pop()+" ");
		    System.out.println();
		
		
	}
}

class StackOfIntegers{
	private int[] elements;
	private int size;
	
	/**Construct a stack with the default capacity 16*/
	public StackOfIntegers(){
		
		this(16);
	}
	
	/**Construct a stack with the specific maximum capacity*/
	public StackOfIntegers(int capacity){
		elements = new int[capacity];
	}
	
	/**push a new integer into the top of the stack*/
	public int push (int value){
		
		if (size >= elements.length){
			int[] temp = new int[elements.length*2];
			System.arraycopy(elements,0,temp,0,elements.length);
			elements = temp;
		}
		
		return elements[size++]=value;
	}
	
	/** return and remove the top element from the stack*/
	public int pop(){
		return elements[--size];
		
	}
	
	/**return the top element from the stack*/
	public int peek(){
		return elements[size-1];
	}
	
	/**test whether the stack is empty*/
	public boolean empty(){
		
		return size==0;
	}
	
	/**return the number of elements in the stack */
	public int getSize(){
		return size;
	}
}