Java tutorial
package br.fucapi.fapeam.monitori.eula; import android.app.Activity; import android.app.AlertDialog; import android.content.DialogInterface; import android.content.SharedPreferences; import android.support.v4.app.FragmentActivity; import java.io.IOException; import java.io.BufferedReader; import java.io.InputStreamReader; import java.io.Closeable; /** * Displays an EULA ("End User License Agreement") that the user has to accept * before using the application. Your application should call * {@link Eula#show(android.app.Activity)} in the onCreate() method of the first * activity. If the user accepts the EULA, it will never be shown again. If the * user refuses, {@link android.app.Activity#finish()} is invoked on your * activity. */ public class Eula { private static final String ASSET_EULA = "EULA"; private static final String PREFERENCE_EULA_ACCEPTED = "eula.accepted"; private static final String PREFERENCES_EULA = "eula"; /** * callback to let the activity know when the user has accepted the EULA. */ static interface OnEulaAgreedTo { /** * Called when the user has accepted the eula and the dialog closes. */ void onEulaAgreedTo(); } /** * Displays the EULA if necessary. This method should be called from the * onCreate() method of your main Activity. * * @param activity * The Activity to finish if the user rejects the EULA. * @return Whether the user has agreed already. */ public static boolean show(final Activity activity, int title, int acceptLabel, int refuseLabel) { final SharedPreferences preferences = activity.getSharedPreferences(PREFERENCES_EULA, Activity.MODE_PRIVATE); if (!preferences.getBoolean(PREFERENCE_EULA_ACCEPTED, false)) { final AlertDialog.Builder builder = new AlertDialog.Builder(activity); builder.setTitle(title); builder.setCancelable(true); builder.setPositiveButton(acceptLabel, new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { accept(preferences); if (activity instanceof OnEulaAgreedTo) { ((OnEulaAgreedTo) activity).onEulaAgreedTo(); } } }); builder.setNegativeButton(refuseLabel, new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { refuse(activity); } }); builder.setOnCancelListener(new DialogInterface.OnCancelListener() { public void onCancel(DialogInterface dialog) { refuse(activity); } }); builder.setMessage(readEula(activity)); builder.create().show(); return false; } return true; } public static void show(final FragmentActivity activity, int title, int closeLabel) { final AlertDialog.Builder builder = new AlertDialog.Builder(activity); builder.setTitle(title); builder.setCancelable(true); builder.setNeutralButton(closeLabel, new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { dialog.cancel(); } }); builder.setMessage(readEula(activity)); builder.create().show(); } private static void accept(SharedPreferences preferences) { preferences.edit().putBoolean(PREFERENCE_EULA_ACCEPTED, true).commit(); } private static void refuse(Activity activity) { activity.finish(); } private static CharSequence readEula(Activity activity) { BufferedReader in = null; try { in = new BufferedReader(new InputStreamReader(activity.getAssets().open(ASSET_EULA))); String line; StringBuilder buffer = new StringBuilder(); while ((line = in.readLine()) != null) buffer.append(line).append('\n'); return buffer; } catch (IOException e) { return ""; } finally { closeStream(in); } } /** * Closes the specified stream. * * @param stream * The stream to close. */ private static void closeStream(Closeable stream) { if (stream != null) { try { stream.close(); } catch (IOException e) { // Ignore } } } }