Java tutorial
/* This file is part of My Expenses. * My Expenses is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * My Expenses is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with My Expenses. If not, see <http://www.gnu.org/licenses/>. */ package org.totschnig.myexpenses.util; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.math.BigDecimal; import java.net.URI; import java.net.URISyntaxException; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import java.text.DateFormat; import java.text.DecimalFormat; import java.text.DecimalFormatSymbols; import java.text.NumberFormat; import java.text.ParseException; import java.text.ParsePosition; import java.util.ArrayList; import java.util.Currency; import java.util.Date; import java.util.Iterator; import java.util.List; import java.util.EnumSet; import org.totschnig.myexpenses.MyApplication; import org.totschnig.myexpenses.R; import org.totschnig.myexpenses.dialog.DonateDialogFragment; import org.totschnig.myexpenses.model.ContribFeature.Feature; import org.totschnig.myexpenses.model.Money; import org.totschnig.myexpenses.provider.TransactionDatabase; import android.app.Activity; import android.content.Context; import android.content.Intent; import android.content.pm.PackageManager; import android.content.pm.PackageManager.NameNotFoundException; import android.content.pm.ResolveInfo; import android.graphics.Color; import android.graphics.PorterDuff; import android.net.Uri; import android.os.Build; import android.os.Environment; import android.provider.Settings.Secure; import android.support.v4.app.FragmentActivity; import android.util.Log; import android.view.View; import android.widget.Toast; /** * Util class with helper methods * @author Michael Totschnig * */ public class Utils { public static char getDefaultDecimalSeparator() { char sep = '.'; NumberFormat nfDLocal = NumberFormat.getNumberInstance(); if (nfDLocal instanceof DecimalFormat) { DecimalFormatSymbols symbols = ((DecimalFormat) nfDLocal).getDecimalFormatSymbols(); sep = symbols.getDecimalSeparator(); } return sep; } /** * <a href="http://www.ibm.com/developerworks/java/library/j-numberformat/">http://www.ibm.com/developerworks/java/library/j-numberformat/</a> * @param strFloat parsed as float with the number format defined in the locale * @return the float retrieved from the string or null if parse did not succeed */ public static BigDecimal validateNumber(DecimalFormat df, String strFloat) { ParsePosition pp; pp = new ParsePosition(0); pp.setIndex(0); df.setParseBigDecimal(true); BigDecimal n = (BigDecimal) df.parse(strFloat, pp); if (strFloat.length() != pp.getIndex() || n == null) { return null; } else { return n; } } public static URI validateUri(String target) { boolean targetParsable; URI uri = null; if (!target.equals("")) { try { uri = new URI(target); String scheme = uri.getScheme(); //strangely for mailto URIs getHost returns null, so we make sure that mailto URIs handled as valid targetParsable = scheme != null && (scheme.equals("mailto") || uri.getHost() != null); } catch (URISyntaxException e1) { targetParsable = false; } if (!targetParsable) { return null; } return uri; } return null; } /** * formats an amount with a currency * @param amount * @param currency * @return formated string */ public static String formatCurrency(Money money) { BigDecimal amount = money.getAmountMajor(); Currency currency = money.getCurrency(); return formatCurrency(amount, currency); } static String formatCurrency(BigDecimal amount, Currency currency) { NumberFormat nf = NumberFormat.getCurrencyInstance(); int fractionDigits = currency.getDefaultFractionDigits(); nf.setCurrency(currency); nf.setMinimumFractionDigits(fractionDigits); nf.setMaximumFractionDigits(fractionDigits); return nf.format(amount); } public static Date fromSQL(String dateString) { try { return TransactionDatabase.dateFormat.parse(dateString); } catch (ParseException e) { return null; } } /** * utility method that calls formatters for date * @param text * @return formated string */ public static String convDate(String text, DateFormat format) { Date date = fromSQL(text); if (date == null) return text; else return format.format(date); } /** * utility method that calls formatters for amount * @param text amount as String retrieved from DB (stored as int minor unit) * @param currency * @return formated string */ public static String convAmount(String text, Currency currency) { return formatCurrency(new Money(currency, Long.valueOf(text))); } /** * @return directory for storing backups and exports, null if external storage is not available */ public static File requireAppDir() { if (!isExternalStorageAvailable()) return null; File sd = Environment.getExternalStorageDirectory(); File appDir = new File(sd, "myexpenses"); appDir.mkdir(); return appDir; } /** * Helper Method to Test if external Storage is Available * from http://www.ibm.com/developerworks/xml/library/x-androidstorage/index.html */ public static boolean isExternalStorageAvailable() { boolean state = false; String extStorageState = Environment.getExternalStorageState(); if (Environment.MEDIA_MOUNTED.equals(extStorageState)) { state = true; } return state; } public static boolean copy(File src, File dst) { FileInputStream srcStream = null; FileOutputStream dstStream = null; try { srcStream = new FileInputStream(src); dstStream = new FileOutputStream(dst); dstStream.getChannel().transferFrom(srcStream.getChannel(), 0, srcStream.getChannel().size()); return true; } catch (FileNotFoundException e) { Log.e("MyExpenses", e.getLocalizedMessage()); return false; } catch (IOException e) { Log.e("MyExpenses", e.getLocalizedMessage()); return false; } finally { try { srcStream.close(); } catch (Exception e) { } try { dstStream.close(); } catch (Exception e) { } } } public static void share(Context ctx, ArrayList<File> files, String target, String mimeType) { URI uri = null; Intent intent; String scheme = "mailto"; boolean multiple = files.size() > 1; if (!target.equals("")) { uri = Utils.validateUri(target); if (uri == null) { Toast.makeText(ctx, ctx.getString(R.string.ftp_uri_malformed, target), Toast.LENGTH_LONG).show(); return; } scheme = uri.getScheme(); } //if we get a String that does not include a scheme, we interpret it as a mail address if (scheme == null) { scheme = "mailto"; } if (scheme.equals("ftp")) { if (multiple) { Toast.makeText(ctx, "sending multiple file through ftp is not supported", Toast.LENGTH_LONG).show(); return; } intent = new Intent(android.content.Intent.ACTION_SENDTO); intent.putExtra(Intent.EXTRA_STREAM, Uri.fromFile(files.get(0))); intent.setDataAndType(android.net.Uri.parse(target), mimeType); if (!isIntentAvailable(ctx, intent)) { Toast.makeText(ctx, R.string.no_app_handling_ftp_available, Toast.LENGTH_LONG).show(); return; } ctx.startActivity(intent); } else if (scheme.equals("mailto")) { if (multiple) { intent = new Intent(android.content.Intent.ACTION_SEND_MULTIPLE); ArrayList<Uri> uris = new ArrayList<Uri>(); for (File file : files) { uris.add(Uri.fromFile(file)); } intent.putParcelableArrayListExtra(Intent.EXTRA_STREAM, uris); } else { intent = new Intent(android.content.Intent.ACTION_SEND); intent.putExtra(Intent.EXTRA_STREAM, Uri.fromFile(files.get(0))); } intent.setType(mimeType); if (uri != null) { String address = uri.getSchemeSpecificPart(); intent.putExtra(Intent.EXTRA_EMAIL, new String[] { address }); } intent.putExtra(Intent.EXTRA_SUBJECT, R.string.export_expenses); if (!isIntentAvailable(ctx, intent)) { Toast.makeText(ctx, R.string.no_app_handling_email_available, Toast.LENGTH_LONG).show(); return; } //if we got mail address, we launch the default application //if we are called without target, we launch the chooser in order to make action more explicit if (uri != null) { ctx.startActivity(intent); } else { ctx.startActivity(Intent.createChooser(intent, ctx.getString(R.string.share_sending))); } } else { Toast.makeText(ctx, ctx.getString(R.string.share_scheme_not_supported, scheme), Toast.LENGTH_LONG) .show(); return; } } public static void setBackgroundFilter(View v, int c) { v.getBackground().setColorFilter(c, PorterDuff.Mode.MULTIPLY); } /** * Indicates whether the specified action can be used as an intent. This * method queries the package manager for installed packages that can * respond to an intent with the specified action. If no suitable package is * found, this method returns false. * * From http://android-developers.blogspot.fr/2009/01/can-i-use-this-intent.html * * @param context The application's environment. * @param action The Intent action to check for availability. * * @return True if an Intent with the specified action can be sent and * responded to, false otherwise. */ public static boolean isIntentAvailable(Context context, Intent intent) { final PackageManager packageManager = context.getPackageManager(); List<ResolveInfo> list = packageManager.queryIntentActivities(intent, PackageManager.MATCH_DEFAULT_ONLY); return list.size() > 0; } public static int getTextColorForBackground(int color) { int greyLevel = (int) (0.299 * Color.red(color) + 0.587 * Color.green(color) + 0.114 * Color.blue(color)); return greyLevel > 127 ? Color.BLACK : Color.WHITE; } public static boolean verifyLicenceKey(String key) { String s = Secure.getString(MyApplication.getInstance().getContentResolver(), Secure.ANDROID_ID) + MyApplication.CONTRIB_SECRET; Long l = (s.hashCode() & 0x00000000ffffffffL); return l.toString().equals(key); } public static void viewContribApp(Activity ctx) { Intent i = new Intent(Intent.ACTION_VIEW); i.setData(Uri.parse("market://details?id=org.totschnig.myexpenses.contrib")); if (Utils.isIntentAvailable(ctx, i)) { ctx.startActivity(i); } else { if (ctx instanceof FragmentActivity) DonateDialogFragment.newInstance().show(((FragmentActivity) ctx).getSupportFragmentManager(), "CONTRIB"); else { //We are called from MyPreferenceActivity where support fragmentmanager is not available ctx.showDialog(R.id.DONATE_DIALOG); } } } /** * @param ctx for retrieving resources * @param other if not null, all features except the one provided will be returned * @return construct a list of all contrib features to be included into a TextView */ public static String getContribFeatureLabelsAsFormattedList(Context ctx, Feature other) { String result = ""; Iterator<Feature> iterator = EnumSet.allOf(Feature.class).iterator(); while (iterator.hasNext()) { Feature f = iterator.next(); if (!f.equals(other)) { result += " - " + ctx.getString(ctx.getResources().getIdentifier( "contrib_feature_" + f.toString() + "_label", "string", ctx.getPackageName())); if (iterator.hasNext()) result += "<br>"; } } return result; } public static String md5(String s) { try { // Create MD5 Hash MessageDigest digest = java.security.MessageDigest.getInstance("MD5"); digest.update(s.getBytes()); byte messageDigest[] = digest.digest(); // Create Hex String StringBuffer hexString = new StringBuffer(); for (int i = 0; i < messageDigest.length; i++) hexString.append(Integer.toHexString(0xFF & messageDigest[i])); return hexString.toString(); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } return ""; } public static class StringBuilderWrapper { public StringBuilderWrapper() { this.sb = new StringBuilder(); } private StringBuilder sb; public StringBuilderWrapper append(String s) { sb.append(s); return this; } public StringBuilderWrapper appendQ(String s) { sb.append(s.replace("\"", "\"\"")); return this; } public String toString() { return sb.toString(); } public void clear() { sb = new StringBuilder(); } } public static <E extends Enum<E>> String joinEnum(Class<E> enumClass) { String result = ""; Iterator<E> iterator = EnumSet.allOf(enumClass).iterator(); while (iterator.hasNext()) { result += "'" + iterator.next().name() + "'"; if (iterator.hasNext()) result += ","; } return result; } /** * Credit: https://groups.google.com/forum/?fromgroups#!topic/actionbarsherlock/Z8Ic8djq-3o * @param item * @param enabled */ public static void menuItemSetEnabled(com.actionbarsherlock.view.Menu menu, int id, boolean enabled) { com.actionbarsherlock.view.MenuItem item = menu.findItem(id); item.setEnabled(enabled); item.getIcon().setAlpha(enabled ? 255 : 90); } }