I am using realm database in my app, and currently in the Application class I am initialising realm with default configuration and everywhere in the app I am using Realm.getDefaultConfiguration() to query/save data.
Now I wanted to encrypt the database and I did as following
RealmConfiguration config = new RealmConfiguration.Builder()
.encryptionKey(getKeyFunction())
.migration(new MyMigration())
.build();
Realm.setDefaultConfiguration(config);`
But when I try to access Realm.getDefaultConfiguration() I get Invalid format of Realm File error.
What am I doing wrong ?
Here is my working code. I have tested this in my sample project
// Generate a key
// IMPORTANT! This is a silly way to generate a key. It is also never stored.
// For proper key handling please consult:
// * https://developer.android.com/training/articles/keystore.html
// * http://nelenkov.blogspot.dk/2012/05/storing-application-secrets-in-androids.html
Realm.init(this);
byte[] key = new byte[64];
new SecureRandom().nextBytes(key);
RealmConfiguration realmConfiguration = new RealmConfiguration.Builder()
.encryptionKey(key)
.build();
// Start with a clean slate every time
Realm.deleteRealm(realmConfiguration);
Realm.setDefaultConfiguration(realmConfiguration);
// Open the Realm with encryption enabled
realm = Realm.getDefaultInstance();
//realm = Realm.getInstance(realmConfiguration);
// Everything continues to work as normal except for that the file is encrypted on disk
realm.executeTransaction(new Realm.Transaction() {
#Override
public void execute(Realm realm) {
Person person = realm.createObject(Person.class);
person.setName("Happy Person");
person.setAge(14);
}
});
Person person = realm.where(Person.class).findFirst();
Log.i(TAG, String.format("Person name: %s", person.getName()));
Normally I use Realm as:
RealmConfiguration config = new RealmConfiguration.Builder(applicationContext).deleteRealmIfMigrationNeeded().build();
How can I add to the assets folder of my project a database with data and read it?
Since Realm Java 0.91.0 there has been an assetFile(String) option on the RealmConfiguration that automatically will copy a file from assets and use that if needed (e.g. if the Realm is opened the first time or has been deleted for some reason):
RealmConfiguration config = new RealmConfiguration.Builder()
.assetFile("path/to/file/in/assets") // e.g "default.realm" or "lib/data.realm"
.deleteRealmIfMigrationNeeded()
.build()
The above will copy the file from assets the first time the Realm is opened or if it has been deleted due to migrations (remember to update the asset Realm in that case).
OLD ANSWER:
It is possible to bundle a Realm database in the assets folder, but then you just need to copy it from there when starting the app the first time.
We have an example of how to copy the files here: https://github.com/realm/realm-java/blob/master/examples/migrationExample/src/main/java/io/realm/examples/realmmigrationexample/MigrationExampleActivity.java#L101-Lundefined
copyBundledRealmFile(this.getResources().openRawResource(R.raw.default_realm), "default.realm");
private String copyBundledRealmFile(InputStream inputStream, String outFileName) {
try {
File file = new File(this.getFilesDir(), outFileName);
FileOutputStream outputStream = new FileOutputStream(file);
byte[] buf = new byte[1024];
int bytesRead;
while ((bytesRead = inputStream.read(buf)) > 0) {
outputStream.write(buf, 0, bytesRead);
}
outputStream.close();
return file.getAbsolutePath();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
Since Realm 0.89.0 RealmConfiguration.initialData(Realm.Transaction) can now be used to populate a Realm file before it is used for the first time.
RealmConfiguration conf = new RealmConfiguration.Builder(context)
.initialData(new Realm.Transaction() {
#Override
public void execute(Realm realm) {
realm.beginTransaction();
realm.createObject(....)
realm.commitTransaction();
}
}).deleteRealmIfMigrationNeeded().name("mRealm.db").build();
Realm realm = Realm.getInstance(conf);
[EDIT] See Stan's answer below. Apparently Realm now supports this directly so you can ignore this answer (unless you're using older Realm versions).
We had a similar need, and also wanted support for a read-only realm database shared with an iOS version of the app.
We created a simple library and have open-sourced it. It includes the copy code given in #christian-melchior's answer, as well as some optional extra tracking for read-only realm database(s) bundled with the APK. Comments and PRs welcomed. See:
https://github.com/eggheadgames/android-realm-asset-helper
Realm has a special parameter in its RealmConfiguration.Builder called assetFile. You could use it like:
realmConfiguration = new RealmConfiguration.Builder()
.assetFile("dataBase/default.realm") // your app's packaged DB
...
.build();
just set yer assets DB path and file name and you are good to go without any android-realm-asset-helper lib or copy-file-from-assets code. In this example my app packaged DB-file lies in "assets/dataBase/default.realm".Note, version below 2 has a bit another way to call assetFile, you should pass context additionally:
realmConfiguration = new RealmConfiguration.Builder(context)
.assetFile(context, "dataBase/default.realm")
.build();
You can use assetFile() method. Please be aware that you can't use assetFile() with deleteIfMigrationNeeded().
I have developed a SDK for android applications.We have many clients using this SDK in there applications.Now i have updated my SDK.I am looking for a way that these changes can reflect in there application without updating there app on play store.Urgent help needed.Any help will be appreciated.Thanks in advance.
Well you can dynamically load a jar file from your SD card using DexLoader class...which you can update when ever you want..on your storage... below is working code..
final String libPath = Environment.getExternalStorageDirectory() + "/test.jar";
final File tmpDir = getDir("dex", 0);
final DexClassLoader classloader = new DexClassLoader(libPath, tmpDir.getAbsolutePath(), null, this.getClass().getClassLoader());
final Class<Object> classToLoad = (Class<Object>) classloader.loadClass("com.test.android.MainActivity");
final Object myInstance = classToLoad.newInstance();
final Method doSomething = classToLoad.getMethod("doSomething");
doSomething.invoke(myInstance);
and in your library file code can be like this
public class MainActivity {
public void doSomething() {
Log.e(MainActivity .class.getName(), "MainActivity : doSomething() called.");
}}
tell me if you need any assistance
there is no such way for your situation. But there is one thing you can do to enable it for next update. Android can dynamically load compiled code with DexClassLoader. So you compile a new DEX file, and then force your SDK to download and use it.
// Internal storage where the DexClassLoader writes the optimized dex file to
final File optimizedDexOutputPath = getDir("outdex", Context.MODE_PRIVATE);
DexClassLoader cl = new DexClassLoader(dexInternalStoragePath.getAbsolutePath(),
optimizedDexOutputPath.getAbsolutePath(),
null,
getClassLoader());
Class libProviderClazz = null;
try {
// Load the library.
libProviderClazz =
cl.loadClass("com.example.dex.lib.LibraryProvider");
// Cast the return object to the library interface so that the
// caller can directly invoke methods in the interface.
// Alternatively, the caller can invoke methods through reflection,
// which is more verbose.
LibraryInterface lib = (LibraryInterface) libProviderClazz.newInstance();
lib.showAwesomeToast(this, "hello");
} catch (Exception e) { ... }
Is there a Java equivalent for System.IO.Path.Combine() in C#/.NET? Or any code to accomplish this?
This static method combines one or more strings into a path.
Rather than keeping everything string-based, you should use a class which is designed to represent a file system path.
If you're using Java 7 or Java 8, you should strongly consider using java.nio.file.Path; Path.resolve can be used to combine one path with another, or with a string. The Paths helper class is useful too. For example:
Path path = Paths.get("foo", "bar", "baz.txt");
If you need to cater for pre-Java-7 environments, you can use java.io.File, like this:
File baseDirectory = new File("foo");
File subDirectory = new File(baseDirectory, "bar");
File fileInDirectory = new File(subDirectory, "baz.txt");
If you want it back as a string later, you can call getPath(). Indeed, if you really wanted to mimic Path.Combine, you could just write something like:
public static String combine(String path1, String path2)
{
File file1 = new File(path1);
File file2 = new File(file1, path2);
return file2.getPath();
}
In Java 7, you should use resolve:
Path newPath = path.resolve(childPath);
While the NIO2 Path class may seem a bit redundant to File with an unnecessarily different API, it is in fact subtly more elegant and robust.
Note that Paths.get() (as suggested by someone else) doesn't have an overload taking a Path, and doing Paths.get(path.toString(), childPath) is NOT the same thing as resolve(). From the Paths.get() docs:
Note that while this method is very convenient, using it will imply an assumed reference to the default FileSystem and limit the utility of the calling code. Hence it should not be used in library code intended for flexible reuse. A more flexible alternative is to use an existing Path instance as an anchor, such as:
Path dir = ...
Path path = dir.resolve("file");
The sister function to resolve is the excellent relativize:
Path childPath = path.relativize(newPath);
The main answer is to use File objects. However Commons IO does have a class FilenameUtils that can do this kind of thing, such as the concat() method.
platform independent approach (uses File.separator, ie will works depends on operation system where code is running:
java.nio.file.Paths.get(".", "path", "to", "file.txt")
// relative unix path: ./path/to/file.txt
// relative windows path: .\path\to\filee.txt
java.nio.file.Paths.get("/", "path", "to", "file.txt")
// absolute unix path: /path/to/filee.txt
// windows network drive path: \\path\to\file.txt
java.nio.file.Paths.get("C:", "path", "to", "file.txt")
// absolute windows path: C:\path\to\file.txt
I know its a long time since Jon's original answer, but I had a similar requirement to the OP.
By way of extending Jon's solution I came up with the following, which will take one or more path segments takes as many path segments that you can throw at it.
Usage
Path.combine("/Users/beardtwizzle/");
Path.combine("/", "Users", "beardtwizzle");
Path.combine(new String[] { "/", "Users", "beardtwizzle", "arrayUsage" });
Code here for others with a similar problem
public class Path {
public static String combine(String... paths)
{
File file = new File(paths[0]);
for (int i = 1; i < paths.length ; i++) {
file = new File(file, paths[i]);
}
return file.getPath();
}
}
To enhance JodaStephen's answer, Apache Commons IO has FilenameUtils which does this. Example (on Linux):
assert org.apache.commons.io.FilenameUtils.concat("/home/bob", "work\\stuff.log") == "/home/bob/work/stuff.log"
It's platform independent and will produce whatever separators your system needs.
Late to the party perhaps, but I wanted to share my take on this. I prefer not to pull in entire libraries for something like this. Instead, I'm using a Builder pattern and allow conveniently chained append(more) calls. It even allows mixing File and String, and can easily be extended to support Path as well. Furthermore, it automatically handles the different path separators correctly on both Linux, Macintosh, etc.
public class Files {
public static class PathBuilder {
private File file;
private PathBuilder ( File root ) {
file = root;
}
private PathBuilder ( String root ) {
file = new File(root);
}
public PathBuilder append ( File more ) {
file = new File(file, more.getPath()) );
return this;
}
public PathBuilder append ( String more ) {
file = new File(file, more);
return this;
}
public File buildFile () {
return file;
}
}
public static PathBuilder buildPath ( File root ) {
return new PathBuilder(root);
}
public static PathBuilder buildPath ( String root ) {
return new PathBuilder(root);
}
}
Example of usage:
File root = File.listRoots()[0];
String hello = "hello";
String world = "world";
String filename = "warez.lha";
File file = Files.buildPath(root).append(hello).append(world)
.append(filename).buildFile();
String absolute = file.getAbsolutePath();
The resulting absolute will contain something like:
/hello/world/warez.lha
or maybe even:
A:\hello\world\warez.lha
If you do not need more than strings, you can use com.google.common.io.Files
Files.simplifyPath("some/prefix/with//extra///slashes" + "file//name")
to get
"some/prefix/with/extra/slashes/file/name"
Here's a solution which handles multiple path parts and edge conditions:
public static String combinePaths(String ... paths)
{
if ( paths.length == 0)
{
return "";
}
File combined = new File(paths[0]);
int i = 1;
while ( i < paths.length)
{
combined = new File(combined, paths[i]);
++i;
}
return combined.getPath();
}
This also works in Java 8 :
Path file = Paths.get("Some path");
file = Paths.get(file + "Some other path");
This solution offers an interface for joining path fragments from a String[] array. It uses java.io.File.File(String parent, String child):
public static joinPaths(String[] fragments) {
String emptyPath = "";
return buildPath(emptyPath, fragments);
}
private static buildPath(String path, String[] fragments) {
if (path == null || path.isEmpty()) {
path = "";
}
if (fragments == null || fragments.length == 0) {
return "";
}
int pathCurrentSize = path.split("/").length;
int fragmentsLen = fragments.length;
if (pathCurrentSize <= fragmentsLen) {
String newPath = new File(path, fragments[pathCurrentSize - 1]).toString();
path = buildPath(newPath, fragments);
}
return path;
}
Then you can just do:
String[] fragments = {"dir", "anotherDir/", "/filename.txt"};
String path = joinPaths(fragments);
Returns:
"/dir/anotherDir/filename.txt"
Assuming all given paths are absolute paths. you can follow below snippets to merge these paths.
String baseURL = "\\\\host\\testdir\\";
String absoluteFilePath = "\\\\host\\testdir\\Test.txt";;
String mergedPath = Paths.get(baseURL, absoluteFilePath.replaceAll(Matcher.quoteReplacement(baseURL), "")).toString();
output path is \\host\testdir\Test.txt.
How to format directory in android project folder as jvm can't see datass.txt or sometimes logcat says read only file...(i am putting datass.txt in main project root)
i am passing an array of strings and want to save it to a file datass.txt so i can retrieve data when internet is not connected
public void FileWrite(String[] temp) throws IOException{
File m = new File("datass.txt");
final String[] descs = temp ;
DataOutputStream out = new DataOutputStream(new
BufferedOutputStream(
new FileOutputStream(m)));
for (int i = 0; i < 31; i ++) {
out.writeUTF(descs[i]);
}
}
You need to add File Writing Permission in your AndroidManiFest.xml file.
android.permission.WRITE_EXTERNAL_STORAGE
Please visit this link for various other permission set.
it seems that you could a Index out of bound exception i am not sure but to guard your self change the for loop header to this
for(int i =0; i < descs.length ; ++i)