Java PreparedStatement SQL syntax error

This is a really weird error that only started appearing today. When I use a prepared statement with ? for parameters, I get an error, but when I use it without parameters, it works just fine. Here is the error-causing code:

    String table = "files";
    Connection conn = DriverManager.getConnection(DB_URL, DB_USER, DB_PASS);
    PreparedStatement prep = conn.prepareStatement("SELECT * FROM ?");
    prep.setString(1, table);
    ResultSet rs = prep.executeQuery();

    while(rs.next()) {
        System.out.println(rs.getString("file_name"));
    }

This produces the following error:

Exception in thread "main" com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''files'' at line 1

Also, changing it to the following works just fine:

    String table = "files";
    Connection conn = DriverManager.getConnection(DB_URL, DB_USER, DB_PASS);
    PreparedStatement prep = conn.prepareStatement("SELECT * FROM " + table);
    ResultSet rs = prep.executeQuery();

    while(rs.next()) {
        System.out.println(rs.getString("file_name"));
    }

This doesn't seem to be making a whole lot of sense. Any ideas?

    String sql = "SELECT * FROM " + ADMIN_AUTH_TABLE + " WHERE " + column + " = '" + hashedPassword + "'";
    PreparedStatement prepared = connection.prepareStatement(sql);

The following doesn't cause errors, but returns a message saying that the password entered is incorrect (it's correct - I double triple checked).

    String sql = "SELECT * FROM " + ADMIN_AUTH_TABLE + " WHERE ? = ?";
    PreparedStatement prepared = connection.prepareStatement(sql);
    prepared.setString(1, column);
    prepared.setString(2, hashedPassword);