utility classes for android development

ActivityUtil.java

package gturedi.gist;

import android.app.Activity;
import android.support.annotation.StringRes;
import android.support.v7.app.AlertDialog;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.ProgressBar;
import android.widget.TextView;

@SuppressWarnings("ResourceType")
public class ActivityUtil {

    private static final int LOADING_PANEL_ID = 12;
    private static final int MESSAGE_PANEL_ID = 13;
    private static final int PROGRESS_SIZE = 50;

    private final Activity activity;
    private ViewGroup root;

    public ActivityUtil(Activity activity) {
        this.activity = activity;
        root = (ViewGroup) activity.findViewById(android.R.id.content);
    }

    public AlertDialog createAlert(@StringRes int title, @StringRes int msg) {
        return createAlert(activity.getString(title), activity.getString(msg));
    }

    public AlertDialog createAlert(String title, String msg) {
        return new AlertDialog.Builder(activity)
                .setTitle(title)
                .setMessage(msg)
                .setNegativeButton(android.R.string.cancel, null)
                .create();
    }

    public void showLoading() {
        AndroidUtil.setVisibilityForChildren(root, View.GONE);
        View loadingPanel = root.findViewById(LOADING_PANEL_ID);
        if (loadingPanel == null) root.addView(createLoadingPanel());
        else loadingPanel.setVisibility(View.VISIBLE);
    }

    public void hideLoading() {
        View panel = root.findViewById(LOADING_PANEL_ID);
        if (panel != null) root.removeView(panel);
        AndroidUtil.setVisibilityForChildren(root, View.VISIBLE);
    }

    public void showMessage(@StringRes int stringRes) {
        showMessage(activity.getString(stringRes));
    }

    public void showMessage(String msg) {
        AndroidUtil.setVisibilityForChildren(root, View.GONE);
        View panel = root.findViewById(MESSAGE_PANEL_ID);
        if (panel == null) root.addView(createMessagePanel(msg));
        else panel.setVisibility(View.VISIBLE);
    }

    public void hideMessage() {
        View panel = root.findViewById(MESSAGE_PANEL_ID);
        if (panel != null) root.removeView(panel);
        AndroidUtil.setVisibilityForChildren(root, View.VISIBLE);
    }

    // helpers //

    private View createLoadingPanel() {
        ProgressBar progressBar = new ProgressBar(activity);
        int size = new ContextUtil(activity.getApplication()).convertDpToPixel(PROGRESS_SIZE);
        progressBar.setLayoutParams(new ViewGroup.LayoutParams(size, size));
        return createPanel(progressBar, LOADING_PANEL_ID);
    }

    private View createMessagePanel(String msg) {
        TextView tv = new TextView(activity);
        tv.setText(msg);
        return createPanel(tv, MESSAGE_PANEL_ID);
    }

    private LinearLayout createPanel(View child, int id) {
        LinearLayout lnr = new LinearLayout(activity);
        lnr.setId(id);
        lnr.setGravity(Gravity.CENTER);
        lnr.setLayoutParams(new ViewGroup.MarginLayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
        lnr.addView(child);
        return lnr;
    }

}

AndroidUtil.java

package gturedi.gist;

import android.content.Intent;
import android.net.Uri;
import android.os.Build;
import android.os.Environment;
import android.support.annotation.IntRange;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Spinner;

import java.util.List;

import gturedi.gist.BuildConfig;

public class AndroidUtil {

    public static boolean isSdCardvailable() {
        return Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED);
    }

    public static Intent createShareIntent(String subject, String text) {
        return new Intent(Intent.ACTION_SEND)
                .setType("text/plain")
                .putExtra(Intent.EXTRA_SUBJECT, subject)
                .putExtra(Intent.EXTRA_TEXT, text);
    }

    public static Intent createMailIntent(String subject, String text, String... receivers) {
        return new Intent(Intent.ACTION_SEND)
                .setType("plain/text")
                .putExtra(Intent.EXTRA_SUBJECT, subject)
                .putExtra(Intent.EXTRA_TEXT, text)
                .putExtra(Intent.EXTRA_EMAIL, receivers);
    }

    public static Intent createMarketIntent() {
        String url = "market://details?id=" + BuildConfig.APPLICATION_ID;
        return createBrowserIntent(url);
    }

    public static Intent createBrowserIntent(String url) {
        return new Intent(Intent.ACTION_VIEW, Uri.parse(url));
    }

    public static Intent createMusicPlayerIntent(String url) {
        return new Intent(Intent.ACTION_VIEW, Uri.parse(url)).setType("audio/*");
    }

    public static Intent createVideoPlayerIntent(String url) {
        return new Intent(Intent.ACTION_VIEW, Uri.parse(url)).setType("video/*");
    }

    public static void navigate(FragmentManager fm, Fragment fragment, boolean addToBackStack) {
        FragmentTransaction trans = fm.beginTransaction()
                .replace(android.R.id.content, fragment)
                .setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
        if (addToBackStack) trans.addToBackStack(fragment.getClass().getSimpleName());
        trans.commit();
    }

    public static void navigate(FragmentManager fm, Fragment fragment) {
        fm.beginTransaction()
                .replace(android.R.id.content, fragment)
                .setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN)
                .addToBackStack(fragment.getClass().getSimpleName())
                .commit();
    }

    public static void bindDataForSpinner(Spinner spinner, List items) {
        ArrayAdapter adapter = new ArrayAdapter<>(
                spinner.getContext(),
                android.R.layout.simple_spinner_dropdown_item,
                items);
        //adapter.setDropDownViewResource(R.layout.support_simple_spinner_dropdown_item);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner.setAdapter(adapter);
    }

    public static void bindDataForListView(ListView listView, List items) {
        ArrayAdapter adapter = new ArrayAdapter<>(
                listView.getContext(),
                android.R.layout.simple_list_item_1,
                items);
        listView.setAdapter(adapter);
    }

    public boolean isApiLevelSupported(@IntRange(from = 2, to = 23) int target) {
        return Build.VERSION.SDK_INT >= target;
    }

    public static void setVisibilityForChildren(ViewGroup parent, int visibility) {
        for (int i = 0; i < parent.getChildCount(); i++) {
            parent.getChildAt(i).setVisibility(visibility);
        }
    }

    public static void setEnabledForChildren(ViewGroup parent, boolean enabled) {
        for (int i = 0; i < parent.getChildCount(); i++) {
            parent.getChildAt(i).setEnabled(enabled);
        }
    }
    
    public static String getTimeAgoString(long time) {
        return DateUtils.getRelativeTimeSpanString(
                time,
                System.currentTimeMillis(),
                DateUtils.SECOND_IN_MILLIS).toString();
    }

}

ContextUtil.java

package gturedi.gist;

import android.app.DownloadManager;
import android.content.Context;
import android.graphics.Point;
import android.location.LocationManager;
import android.net.ConnectivityManager;
import android.net.Uri;
import android.support.annotation.ColorRes;
import android.support.annotation.StringRes;
import android.util.DisplayMetrics;
import android.view.Display;
import android.view.View;
import android.view.WindowManager;
import android.view.inputmethod.InputMethodManager;
import android.widget.Toast;

public class ContextUtil {

    private final Context ctx;

    public ContextUtil(Context ctx) {
        this.ctx = ctx;
    }

    public void showToast(@StringRes int resId) {
        showToast(ctx.getString(resId));
    }

    public void showToast(String msg) {
        Toast.makeText(ctx, msg, Toast.LENGTH_SHORT).show();
    }

    // requires permission: ACCESS_NETWORK_STATE
    public boolean isNetworkAvailable() {
        ConnectivityManager cm = (ConnectivityManager) ctx.getSystemService(Context.CONNECTIVITY_SERVICE);
        return cm.getActiveNetworkInfo() != null
                && cm.getActiveNetworkInfo().isAvailable()
                && cm.getActiveNetworkInfo().isConnected();
    }

    // requires permission: ACCESS_FINE_LOCATION (for pre-lollipop)
    public boolean isGpsAvailable() {
        LocationManager lm = (LocationManager) ctx.getSystemService(Context.LOCATION_SERVICE);
        return lm.isProviderEnabled(LocationManager.GPS_PROVIDER);
    }

    public Point getScreenDimensions() {
        WindowManager wm = (WindowManager) ctx.getSystemService(Context.WINDOW_SERVICE);
        Display display = wm.getDefaultDisplay();
        Point size = new Point();
        display.getSize(size);
        return size;
    }

    public int convertDpToPixel(float dp) {
        DisplayMetrics metrics = ctx.getResources().getDisplayMetrics();
        return  (int) (dp * (metrics.densityDpi / 160f));
    }

    public int convertPixelsToDp(int px) {
        DisplayMetrics metrics = ctx.getResources().getDisplayMetrics();
        return (int) (px / (metrics.densityDpi / 160f));
    }

    public void hideKeyboard(View target) {
        try {
            InputMethodManager imm = (InputMethodManager) ctx.getSystemService(Context.INPUT_METHOD_SERVICE);
            imm.hideSoftInputFromWindow(target.getApplicationWindowToken(), 0);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public void startDownloadManager(String url) {
        DownloadManager dm = (DownloadManager) ctx.getSystemService(Context.DOWNLOAD_SERVICE);
        DownloadManager.Request request = new DownloadManager.Request(Uri.parse(url));
        dm.enqueue(request);
    }

    public String str(@StringRes int id) {
        return ctx.getString(id);
    }

    public int color(@ColorRes int id) {
        return ctx.getResources().getColor(id);
    }

}

FileUtil.java

package gturedi.gist;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;

public class FileUtil {

    public static final String UTF_8 = "utf-8";

    public static void deleteRecursively(File dir) {
        if (dir.isDirectory()) {
            for (String item : dir.list()) {
                deleteRecursively(new File(dir, item));
            }
        }
        dir.delete();
    }

    public static String convertStreamToString(InputStream in) {
        try {
            return new String(convertStreamToByteArray(in), UTF_8);
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
            return "";
        }
    }

    public static byte[] convertStreamToByteArray(InputStream in) {
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        copyStream(in, out);
        return out.toByteArray();
    }

    public static void copyStream(InputStream in, OutputStream out) {
        try {
            int bytesRead;
            byte[] buffer = new byte[4096];
            while ((bytesRead = in.read(buffer)) != -1) {
                out.write(buffer, 0, bytesRead);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                in.close();
                out.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

}

GeneralUtil.java

package gturedi.gist;

import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.List;

public class GeneralUtil {

    public static String replaceIfEmpty(String input, String defaultValue) {
        return isNullOrEmpty(input) ? defaultValue : input;
    }

    public static boolean isNullOrEmpty(String target) {
        return target == null || target.equals("");
    }

    public static boolean isNullOrEmpty(List target) {
        return target == null || target.size() == 0;
    }

    public static boolean isNullOrEmpty(Object[] target) {
        return target == null || target.length == 0;
    }

    public static List<String> selectField(List items, String fieldName) {
        List<String> result = new ArrayList<>(items.size());
        for (Object item : items) {
            try {
                Field field = item.getClass().getField(fieldName);
                String val = field.get(item).toString();
                result.add(val);
            } catch (NoSuchFieldException e) {
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }
        }
        return result;
    }

    public static void runAsync(Runnable runnable) {
        new Thread(runnable).start();
    }

}

HttpUtil.java

package gturedi.gist;

import java.io.FileOutputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.Map;

public class HttpUtil {

    public static final String UA_ANDROID_LG = "Mozilla/5.0 (Linux; U; Android 4.0.3; ko-kr; LG-L160L Build/IML74K) AppleWebkit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30";

    public static String makePost(String url, Map<String, String> headers, byte[] params) {
        try {
            HttpURLConnection con = (HttpURLConnection) new URL(url).openConnection();
            con.setDoOutput(true);
            con.setDoInput(true);

            con.setRequestProperty("User-Agent", UA_ANDROID_LG);
            con.setRequestProperty("Content-Type", "application/json; charset=UTF-8");
            con.setRequestProperty("Accept", "application/json");
            con.setRequestMethod("POST");

            if (headers != null)
                for (Map.Entry<String, String> item : headers.entrySet())
                    con.setRequestProperty(item.getKey(), item.getValue());

            OutputStream os = con.getOutputStream();
            os.write(params);
            os.close();

            return FileUtil.convertStreamToString(con.getInputStream());
        } catch (Exception e) {
            e.printStackTrace();
            return "";
        }
    }

    public static String makeGet(String url, Map<String, String> headers, Map<String, String> params) {
        try {
            url = url + createUrlParams(params);
            HttpURLConnection conn = (HttpURLConnection) new URL(url).openConnection();
            conn.addRequestProperty("User-Agent", UA_ANDROID_LG);
            addHeaders(conn, headers);
            return FileUtil.convertStreamToString(conn.getInputStream());
        } catch (Exception e) {
            e.printStackTrace();
            return "";
        }
    }

    public static void downloadFile(String url, String path) {
        try {
            HttpURLConnection conn = (HttpURLConnection) new URL(url).openConnection();
            conn.addRequestProperty("User-Agent", UA_ANDROID_LG);
            FileOutputStream out = new FileOutputStream(path);
            FileUtil.copyStream(conn.getInputStream(), out);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    // helpers //

    private static String createUrlParams(Map<String, String> params) {
        StringBuilder result = new StringBuilder("?");
        for (Map.Entry<String, String> item : params.entrySet()) {
            String charset = "utf-8";
            try {
                result.append(URLEncoder.encode(item.getKey(), charset))
                        .append("=")
                        .append(URLEncoder.encode(item.getValue(), charset))
                        .append("&");
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }
        }
        return result.toString();
    }

    private static void addHeaders(HttpURLConnection conn, Map<String, String> headers) {
        if (headers != null && headers.size() > 0) {
            for (Map.Entry<String, String> item : headers.entrySet()) {
                conn.addRequestProperty(item.getKey(), item.getValue());
            }
        }
    }

}