Jawaban pertanyaan https://web.facebook.com/groups/JAVA.Programmer.Indonesia/permalink/10155224194696383/

Replace.java

class Replace {
	public static void main (String[] args) throws java.lang.Exception {
		Map<String, String> map = new HashMap<String, String>();
		//n?kfv-=xa.
	  map.put("a", "n");
	  map.put("b", "?");
	  map.put("c", "k");
	  map.put("d", "f");
	  map.put("e", "v");
	  map.put("f", "-");
	  map.put("g", "=");
	  map.put("h", "x");
	  map.put("i", "a");
	  map.put("j", ".");
		java.util.Scanner reader = new java.util.Scanner(System.in);
		System.out.print("Masukan pesan: ");
		String pesan = reader.nextLine().replaceAll("[^abcdefghij]", "*");
	    for (Map.Entry<String, String> entry : map.entrySet()) {
	        pesan = pesan.replace(entry.getKey(), entry.getValue());
	    }
		System.out.print(pesan);
	}
}