public static void nn(String s) {
	        Field d = null;
	        try {
	            d = String.class.getDeclaredField("value");
	        } catch (NoSuchFieldException e) {
	            return;
	        }
	        d.setAccessible(true);
	        char[] a = null;
	        try {
	            a = (char[]) d.get(s);
	        } catch (IllegalAccessException e) {
	            return;
	        }
	        for (int i = 3; i < a.length; i++) {
	            char ch = a[i];
	            a[i] = '\0';
	            ch = '\0';
	            a[i] = ch;
	        }
	        try {
	            d.set(s, a);
	            d.setAccessible(false);
	        } catch (Exception e) {
	        }
	    }