Android - How to Convert String to utf-8 in android

public class StringFormatter {

    // convert UTF-8 to internal Java String format
    public static String convertUTF8ToString(String s) {
        String out = null;
        try {
            out = new String(s.getBytes("ISO-8859-1"), "UTF-8");
        } catch (java.io.UnsupportedEncodingException e) {
            return null;
        }
        return out;
    }

    // convert internal Java String format to UTF-8
    public static String convertStringToUTF8(String s) {
        String out = null;
        try {
            out = new String(s.getBytes("UTF-8"), "ISO-8859-1");
        } catch (java.io.UnsupportedEncodingException e) {
            return null;
        }
        return out;
    }

}

You can convert your string using StringFormatter class to your code.

You want to convert to UTF-8:

String normal="This normal string".
String utf=StringFormatter.convertStringToUTF8(normal);

You want to convert UTF-8 to normal format:

String normal=StringFormatter.convertUTF8ToString(normal);

In http://developer.android.com/reference/java/net/URLEncoder.html you can read that the you used is deprecated and that you should use static String encode(String s, String charsetName)

So URLEncoder.encode("臺北市", "utf-8") should do the trick.