Java tutorial
/* * Copyright 2013-2015 The GDG Frisbee Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.gdg.frisbee.android.utils; import android.content.Context; import android.content.Intent; import android.content.pm.PackageManager; import android.content.res.Resources; import android.net.ConnectivityManager; import android.net.Uri; import android.support.annotation.NonNull; import android.support.customtabs.CustomTabsIntent; import android.util.DisplayMetrics; import android.util.Patterns; import android.util.TypedValue; import com.google.gson.FieldNamingPolicy; import com.google.gson.Gson; import com.google.gson.GsonBuilder; import com.google.gson.JsonDeserializer; import org.gdg.frisbee.android.R; import org.gdg.frisbee.android.api.deserializer.DateTimeDeserializer; import org.joda.time.DateTime; import org.joda.time.Period; import org.joda.time.format.DateTimeFormat; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.UnsupportedEncodingException; import java.net.URL; import java.net.URLDecoder; import java.util.HashMap; import java.util.Map; public class Utils { private Utils() { // Prevent instances of this class being created. } /** * Converts dp value to px value. * * @param res Resources objects to get displayMetrics. * @param dp original dp value. * @return px value. */ public static int dpToPx(@NonNull Resources res, int dp) { return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, res.getDisplayMetrics()); } public static float convertPixelsToDp(float px, Context context) { Resources resources = context.getResources(); DisplayMetrics metrics = resources.getDisplayMetrics(); return px / (metrics.densityDpi / 160f); } public static String getUppercaseLetters(String in) { StringBuilder sb = new StringBuilder(); for (int i = 0; i < in.length(); i++) { char c = in.charAt(i); if (Character.isUpperCase(c)) { sb.append(c); } } return sb.toString(); } public static Map<String, String> splitQuery(URL url) throws UnsupportedEncodingException { Map<String, String> queryPairs = new HashMap<>(); String query = url.getQuery(); if (query == null) { return queryPairs; } String[] pairs = query.split("&"); for (String pair : pairs) { int idx = pair.indexOf("="); queryPairs.put(URLDecoder.decode(pair.substring(0, idx), "UTF-8"), URLDecoder.decode(pair.substring(idx + 1), "UTF-8")); } return queryPairs; } public static String toHumanTimePeriod(Context ctx, DateTime start, DateTime end) { String result; Resources res = ctx.getResources(); Period p = new Period(start, end); if (p.getYears() == 0 && p.getMonths() == 0 && p.getWeeks() == 0 && p.getDays() == 0 && p.getHours() == 0 && p.getMinutes() == 0) { result = res.getQuantityString(R.plurals.seconds_ago, p.getSeconds(), p.getSeconds()); } else if (p.getYears() == 0 && p.getMonths() == 0 && p.getWeeks() == 0 && p.getDays() == 0 && p.getHours() == 0) { result = res.getQuantityString(R.plurals.minutes_ago, p.getMinutes(), p.getMinutes()); } else if (p.getYears() == 0 && p.getMonths() == 0 && p.getWeeks() == 0 && p.getDays() == 0) { result = res.getQuantityString(R.plurals.hours_ago, p.getHours(), p.getHours()); } else if (p.getYears() == 0 && p.getMonths() == 0 && p.getWeeks() == 0) { result = res.getQuantityString(R.plurals.days_ago, p.getDays(), p.getDays()); } else { result = start.toLocalDateTime() .toString(DateTimeFormat.patternForStyle("M-", res.getConfiguration().locale)); } return result; } public static boolean isOnline(Context context) { ConnectivityManager mConMgr = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE); return mConMgr.getActiveNetworkInfo() != null && mConMgr.getActiveNetworkInfo().isAvailable() && mConMgr.getActiveNetworkInfo().isConnected(); } public static long stringToLong(String str) { long l = 0; for (int i = 0; i < str.length(); i++) { l += str.charAt(i) * Math.pow(10, i); } return l; } public static String inputStreamToString(InputStream is) throws IOException { BufferedReader reader = new BufferedReader(new InputStreamReader(is)); StringBuilder sb = new StringBuilder(); String line; while ((line = reader.readLine()) != null) { sb.append(line); } is.close(); return sb.toString(); } public static Gson getGson() { return new GsonBuilder().registerTypeAdapter(DateTime.class, new DateTimeDeserializer()).create(); } public static Gson getGson(FieldNamingPolicy policy) { return new GsonBuilder().setFieldNamingPolicy(policy) .registerTypeAdapter(DateTime.class, new DateTimeDeserializer()).create(); } public static Gson getGson(FieldNamingPolicy policy, JsonDeserializer<DateTime> dateTimeDeserializer) { return new GsonBuilder().setFieldNamingPolicy(policy) .registerTypeAdapter(DateTime.class, dateTimeDeserializer).create(); } /** * Utility function to check if the provided String is an email or not. * * @param possibleEmail Given String. * @return true if the given String is an email address. */ public static boolean isEmailAddress(String possibleEmail) { return Patterns.EMAIL_ADDRESS.matcher(possibleEmail).matches(); } public static boolean canLaunch(Context context, final Intent viewUrlIntent) { return context.getPackageManager().resolveActivity(viewUrlIntent, PackageManager.MATCH_DEFAULT_ONLY) != null; } @SuppressWarnings("deprecation") public static Intent createExternalIntent(Context context, Uri uri) { CustomTabsIntent customTabsIntent = new CustomTabsIntent.Builder() .setToolbarColor(context.getResources().getColor(R.color.theme_primary)).setShowTitle(true).build(); Intent intent = customTabsIntent.intent; intent.setData(uri); return intent; } }