import java.security.SecureRandom;
import java.util.Random;

public class PasswordUtils {
	
	static char[] SYMBOLS= "^$*.[]{}()?-\"!@#%&amp;/\\,><':;|_~`".toCharArray();
	static char[] LOWERCASE= "abcdefghijklmnopqrstuvwxyz".toCharArray();
	static char[] UPPERCASE= "ABCDEFGHIJKLMNOPQRSTUVWXYZ".toCharArray();
	static char[] NUMBERS= "0123456789".toCharArray();
	static char[] ALL_CHARS= "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789^$*.[]{}()?-\"!@#%&amp;	/\\,><':;|_~`".toCharArray();
	static Random rand= new SecureRandom();
	
	public static String getPassword(int length) {
	    assert length >= 4;
		char[] password= new char[length];
		//get the requirements out of the way
		password[0]= LOWERCASE[rand.nextInt(LOWERCASE.length)];
		password[1]= UPPERCASE[rand.nextInt(UPPERCASE.length)];
		password[2]= NUMBERS[rand.nextInt(NUMBERS.length)];
		password[3]= SYMBOLS[rand.nextInt(SYMBOLS.length)];
		
		//populate rest of the password with random chars
		for (int i= 4; i < length; i++) {
		    password[i]= ALL_CHARS[rand.nextInt(ALL_CHARS.length)];
		}
		
		//shuffle it up
		for (int i= 0; i < password.length; i++) {
		    int randomPosition= rand.nextInt(password.length);
			char temp= password[i];
			password[i]= password[randomPosition];
			password[randomPosition]= temp;
		}
		return new String(password);
	}

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		for (int i= 0; i < 100; i++) {
            System.out.println(getPassword(8));
        }
	}

}