I need to get dimensions defined in XML files under Android folder from classes in Core directory of libgdx.
I know I can use assets folder for accessing drawables. But how about dimensions or strings?
You can't access this kind of platform specific information directly in the core project. But this can be achieved by interfacing these functions with a Facade, providing a platform-specific implementation for each target.
In libgdx-wiki there is an example for platform specific interfaces.
public interface PlatformSpecificStuff {
public String getString();
public int getDimensions();
}
// In -Android project
public class AndroidSpecificStuff implements PlatformSpecificStuff {
public String getString(){
// do whaterver you want with the resources.
return "string resource";
}
public int getDimensions(){
// do whaterver you want with the resources.
return 42;
}
}
// In -Desktop project
public class DesktopSpecificStuff implements PlatformSpecificStuff {
public String getString(){
// there is no xml or any andorid specific resource
return null;
}
public int getDimensions(){
// there is no xml or any andorid specific resource
return 0;
}
}
public class MyGame implements ApplicationListener {
private final PlatformSpecificStuff pss;
public MyGame(PlatformSpecificStuff pss) {
this.pss= pss;
}
}
Update: I don't know what are trying to accomplish by getting the dimensions as android resources. But you are probably in wrong track. If you want to support multiple screen sizes, have a look at viewports
Related
I am not sure of the terminology for what I'm looking to do, so sorry in advance!
I've found a FilePicker plugin for Xamarin.Forms (https://github.com/Studyxnet/FilePicker-Plugin-for-Xamarin-and-Windows) that implements device-specific functionality for selecting files via the CrossFilePicker class.
The way to use leverage this functionality would be something like
CrossFilePicker.Current.OpenFile("Filename.txt");
The most important part of this for me is that CrossFilePicker.Current is static and can be accessible from anywhere in the shared layer of my Xamarin.Forms app.
I need to implement a class with the same characteristics. I want to leverage device Accessibility functionality (i.e. determining if a screen reader is enabled) and I need to be able to do so with a static class.
My eventual plan is to then wrap this static class so that I can use it for unit tests too.
I don't want to import device libraries into my shared project.
TLDR: I need a static class that implements device-specific functionality.
Any help would be greatly appreciated! Thank you :)
EDIT:
Here are the files I have currently implemented in my project
IAccessibilityService Located in the shared .NET project
namespace Bitspace.Services
{
public interface IAccessibilityService
{
public bool IsScreenReaderEnabled();
public void Announcement(string message);
public void NavigationAnnouncement(string message);
}
}
DeviceAccessibility.cs Located in the shared .NET project
using System;
namespace Bitspace.Services
{
public class DeviceAccessibility
{
private static Lazy<IAccessibilityService> Implementation = new Lazy<IAccessibilityService>(() => CreateAccessibilityService(), System.Threading.LazyThreadSafetyMode.PublicationOnly);
public static IAccessibilityService Current
{
get
{
var curr = Implementation.Value;
if (curr == null)
{
throw new Exception();
}
return curr;
}
}
private static IAccessibilityService CreateAccessibilityService()
{
return new DeviceAccessibilityImplementation();
}
}
}
DeviceAccessibilityImplementation.cs Located in the Android project
using Android.Runtime;
namespace Bitspace.Services
{
[Preserve (AllMembers = true)]
public class DeviceAccessibilityImplementation : IAccessibilityService
{
public bool IsScreenReaderEnabled()
{
return true;
}
public void Announcement(string message)
{
}
public void NavigationAnnouncement(string message)
{
}
}
}
If I try to build the project, I get an error on the return new DeviceAccessibilityImplementation(); line in DeviceAccessibility.cs that says DeviceAccessibility.cs(25, 24): [CS0246] The type or namespace name 'DeviceAccessibilityImplementation' could not be found (are you missing a using directive or an assembly reference?)
However, CTRL Clicking on that line takes me to the DeviceAccessibilityImplementation.cs
Java compiler does not preserve parameter names for any interface, unless newer compiler option -parameter is used (I am not sure how to use it with android studio) - refer example below.
Since java compiler does not preserve parameters names, Android Studio "code -> implement methods" is not able to generate code with original parameter names.
The question is, how to implement a library module so that Android Studio Menu, Code->Implement Methods correctly generates code with all the original parameter names.
For example, following is a simple class and an interface. This class is in a separate aar module. When application uses this AAR, implements TablaListener and asks AndroidStudio to generate interface methods stubs, the parameter names are not preserved.
Please note that proguard is NOT used.
Any ideas?
public class TablaCore {
public interface TablaListener {
/**
* #param params
* #param data
* #return
*/
boolean TablaCore_onAction(String params, byte[] data);
}
private static TablaListener mListener = null;
public static void setListener(TablaListener myListener) {
mListener = myListener;
}
public TablaListener getListener() {
return mListener;
}
}
It is easy to demonstrate by compiling and decompiling above class. This is decompiled version
public class TablaCore
{
private static TablaListener mListener = null;
public static void setListener(TablaListener myListener)
{
mListener = myListener;
}
public TablaListener getListener()
{
return mListener;
}
public static abstract interface TablaListener
{
public abstract boolean TablaCore_onAction(String paramMessageParams, byte[] paramArrayOfByte);
}
}
You have to include Android SDK source code.
Go to: File > Settings... > Apperance & Behavior > System Settings > Android SDK
On the tab SDK Platforms select Show Package Details and find and select appropriate Sources for Android XX. Unfortunately, currently for Android API 27, there is no sources, but there is for Sources for Android 26. Apply changes - the download window should appear automatically.
After downloading and restarting implementing methods should use proper names for method parameters.
I'm following this tutorial and this Custom Detector Example in order to implement Custom Lint Rules. Basically what I've done is:
Create a new Android Project in Android Studio;
Create a java module for project created in step 1;
On module's build.gradle, import Lint API dependencies;
Create an Issue & IssueRegistry & CustomDetector;
Reference the IssueRegistry on module's build.gradle;
Create Unit tests;
My problem is, during the execution of my JUnits, I always receive "No Warning". When I debug the test, I can see that my Custom Detector isn't called, what am I doing wrong?
Strings.java
public class Strings {
public static final String STR_ISSUE_001_ID = "VarsMustHaveMoreThanOneCharacter";
public static final String STR_ISSUE_001_DESCRIPTION = "Avoid naming variables with only one character";
public static final String STR_ISSUE_001_EXPLANATION = "Variables named with only one character do not pass any meaning to the reader. " +
"Variables name should clear indicate the meaning of the value it is holding";
}
Issues.java
public class Issues {
public static final
Issue ISSUE_001 = Issue.create(
STR_ISSUE_001_ID,
STR_ISSUE_001_DESCRIPTION,
STR_ISSUE_001_EXPLANATION,
SECURITY,
// Priority ranging from 0 to 10 in severeness
6,
WARNING,
new Implementation(VariableNameDetector.class, ALL_RESOURCES_SCOPE)
);
}
IssuesRegistry.java
public class IssueRegistry extends com.android.tools.lint.client.api.IssueRegistry {
#Override
public List<Issue> getIssues() {
List<Issue> issues = new ArrayList<>();
issues.add(ISSUE_001);
return issues;
}
}
VariableNameDetector.java
public class VariableNameDetector extends Detector implements Detector.JavaScanner {
public VariableNameDetector() {
}
#Override
public boolean appliesToResourceRefs() {
return false;
}
#Override
public boolean appliesTo(Context context, File file) {
return true;
}
#Override
#Nullable
public AstVisitor createJavaVisitor(JavaContext context) {
return new NamingConventionVisitor(context);
}
#Override
public List<String> getApplicableMethodNames() {
return null;
}
#Override
public List<Class<? extends Node>> getApplicableNodeTypes() {
List<Class<? extends Node>> types = new ArrayList<>(1);
types.add(lombok.ast.VariableDeclaration.class);
return types;
}
#Override
public void visitMethod(
JavaContext context,
AstVisitor visitor,
MethodInvocation methodInvocation
) {
}
#Override
public void visitResourceReference(
JavaContext context,
AstVisitor visitor,
Node node,
String type,
String name,
boolean isFramework
) {
}
private class NamingConventionVisitor extends ForwardingAstVisitor {
private final JavaContext context;
NamingConventionVisitor(JavaContext context) {
this.context = context;
}
#Override
public boolean visitVariableDeclaration(VariableDeclaration node) {
StrictListAccessor<VariableDefinitionEntry, VariableDeclaration> varDefinitions =
node.getVariableDefinitionEntries();
for (VariableDefinitionEntry varDefinition : varDefinitions) {
String name = varDefinition.astName().astValue();
if (name.length() == 1) {
context.report(
ISSUE_001,
context.getLocation(node),
STR_ISSUE_001_DESCRIPTION
);
return true;
}
}
return false;
}
}
}
build.gradle
apply plugin: 'java'
configurations {
lintChecks
}
ext {
VERSION_LINT_API = '24.3.1'
VERSION_LINT_API_TESTS = '24.3.1'
}
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation "com.android.tools.lint:lint-api:$VERSION_LINT_API"
implementation "com.android.tools.lint:lint-checks:$VERSION_LINT_API"
testImplementation "com.android.tools.lint:lint-tests:$VERSION_LINT_API_TESTS"
}
jar {
manifest {
attributes('Lint-Registry': 'br.com.edsilfer.lint_rules.resources.IssueRegistry')
}
}
sourceCompatibility = "1.7"
targetCompatibility = "1.7"
TestVariableNameDetector.java
private static final String ARG_DEFAULT_LINT_SUCCESS_LOG = "No warnings.";
#Override
protected Detector getDetector() {
return new VariableNameDetector();
}
#Override
protected List<Issue> getIssues() {
return Collections.singletonList(Issues.ISSUE_001);
}
public void test_file_with_no_variables_with_length_equals_01() throws Exception {
assertEquals(
ARG_DEFAULT_LINT_SUCCESS_LOG,
lintProject(java("assets/Test.java", "public class Test {public String sampleVariable;}"))
);
}
public void test_file_with_variables_with_length_equals_01() throws Exception {
assertEquals(
ARG_DEFAULT_LINT_SUCCESS_LOG,
lintProject(java("assets/Test3.java", "public class Test {public String a;bnvhgvhj}"))
);
}
}
P.S.: on Java's module I do not have access to assetsor res folder, that is the reason why I've created a String.java and I'm using java(to, source) in my Unit test - I assumed that this java method does the same as the xml from the tutorial link I referenced at the top of this question.
It turned out that in my case the problem was with the JUnit itself. I think that the way I was attempting to simulate the file was wrong. The text below is part of the README.md of a sample project that I've created in order to document what I've learned from this API and answers the question in the title:
Create
Create a new Android Project;
Create a new Java Library Module - Custom Lint Rules are packaged into .jar libraries once they are ready, therefore the easiest way to implement them using them is inside a Java Module Library;
On module's build.gradle:
add target and source compatibility to Java 1.7;
add dependencies for lint-api, lint-checks and test dependencies;
add jar packing task containing two attributes: Manifest-Version and Lint-Registry, set the first to 1.0 and the second as the full path to a class that will later on contain the issue's catalog;
add a default tasl assemble;
[OPTIONAL]: add a task that will copy the generated .jar into ~/.android/lint;
Check REF001 and choose a Detector that best suits your needs, based on it create and implement a class to fulfill the Detector's role;
Still based on REF0001 chosen file, create and implement a Checker class, later referring to it inside Detector's createJavaVisitor() method;
for the sake of SRP, do not place Checker in the same file of Detector's class;
Copy the generated .jar file from build/lib to ~/.android/lint - if you added a task on build.gradle that does this you can skip this step;
Restart the computer - once created and moved into ~/.android/lint, the Custom Rules should be read by Lint next time the program starts. In order to have the alert boxes inside Android Studio, it is enough to invalidate caches and restart the IDE, however, to have your custom rules caught on Lint Report when ./gradlew check, it might be necessary to restart your computer;
Testing Detectors and Checkers
Testing Custom Rules is not an easy task to do - mainly due the lack of documentation for official APIs. This section will present two approaches for dealing with this. The main goal of this project is to create custom rules that will be run against real files, therefore, test files will be necessary for testing them. They can be places in src/test/resources folder from your Lint Java Library Module;
Approach 01: LintDetectorTest
Make sure you've added all test dependencies - checkout sample project's build.gradle;
Copy EnhancedLintDetectorTest.java and FileUtils.java into your project's test directory;
There is a known bug with Android Studio that prevents it from seeing files from src/test/resources folder, these files are a workaround for that;
EnhancedLintDetectorTest.java should return all issues that will be subject of tests. A nice way to do so is getting them from Issue Registry;
Create a test class that extends from EnhancedLintDetectorTest.java;
Implement getDetector() method returning an instance of the Detector to be tested;
Use lintFiles("test file path taking resources dir as root") to perform the check of the Custom Rules and use its result object to assert the tests;
Note that LintDetectorTest.java derives from TestCase.java, therefore, you're limited to JUnit 3.
Approach 02: Lint JUnit Rule
You might have noticed that Approach 01 might be a little overcomplicated, despite the fact that you're limited to JUnit 3 features. Because of that GitHub user a11n created a Lint JUnit Rule that allows the test of Custom Lint Rules in a easier way that counts with JUnit 4 and up features. Please, refer to his project README.md for details about how to create tests using this apprach.
Currently, Lint JUnit Rule do not correct the root dir for test files and you might no be able to see the tests passing from the IDE - however it works when test are run from command line. An issue and PR were created in order to fix this bug.
I'm not sure how to use the AST Api, however I'm personally using Psi and this is one of my lint checks that are working for me.
public final class RxJava2MethodCheckReturnValueDetector extends Detector implements Detector.JavaPsiScanner {
static final Issue ISSUE_METHOD_MISSING_CHECK_RETURN_VALUE =
Issue.create("MethodMissingCheckReturnValue", "Method is missing the #CheckReturnValue annotation",
"Methods returning RxJava Reactive Types should be annotated with the #CheckReturnValue annotation.",
MESSAGES, 8, WARNING,
new Implementation(RxJava2MethodCheckReturnValueDetector.class, EnumSet.of(JAVA_FILE, TEST_SOURCES)));
#Override public List<Class<? extends PsiElement>> getApplicablePsiTypes() {
return Collections.<Class<? extends PsiElement>>singletonList(PsiMethod.class);
}
#Override public JavaElementVisitor createPsiVisitor(#NonNull final JavaContext context) {
return new CheckReturnValueVisitor(context);
}
static class CheckReturnValueVisitor extends JavaElementVisitor {
private final JavaContext context;
CheckReturnValueVisitor(final JavaContext context) {
this.context = context;
}
#Override public void visitMethod(final PsiMethod method) {
final PsiType returnType = method.getReturnType();
if (returnType != null && Utils.isRxJava2TypeThatRequiresCheckReturnValueAnnotation(returnType)) {
final PsiAnnotation[] annotations = method.getModifierList().getAnnotations();
for (final PsiAnnotation annotation : annotations) {
if ("io.reactivex.annotations.CheckReturnValue".equals(annotation.getQualifiedName())) {
return;
}
}
final boolean isMethodMissingCheckReturnValueSuppressed = context.getDriver().isSuppressed(context, ISSUE_METHOD_MISSING_CHECK_RETURN_VALUE, method);
if (!isMethodMissingCheckReturnValueSuppressed) {
context.report(ISSUE_METHOD_MISSING_CHECK_RETURN_VALUE, context.getLocation(method.getNameIdentifier()), "Method should have #CheckReturnValue annotation");
}
}
}
}
}
Checkout the many more I wrote here.
I am trying to build a library. I have an Android library project and some resources under the res directory that I want to access in the library project's code. The Android docs says:
source code in the library module can access its own resources through its R class
But I just can't figure out how to do this. Because it's a library and intended to be used from other applications, not run itself, I have no Activity, so I can't get a Context to use getResources(). How can I access these resources explicitly without a context?
Without an Activity, it doesn't seem possible to use the R class. If you have a test application within your library, the test application will be able to access R, but not from the lib itself.
Still, you can access the resources by name.
For instance, I have a class like this inside my library,
public class MyContext extends ContextWrapper {
public MyContext(Context base) {
super(base);
}
public int getResourceId(String resourceName) {
try{
// I only access resources inside the "raw" folder
int resId = getResources().getIdentifier(resourceName, "raw", getPackageName());
return resId;
} catch(Exception e){
Log.e("MyContext","getResourceId: " + resourceName);
e.printStackTrace();
}
return 0;
}
}
(See https://stackoverflow.com/a/24972256/1765629 for more information about ContextWrappers)
And the constructor of an object in the library takes that context wrapper,
public class MyLibClass {
public MyLibClass(MyContext context) {
int resId = context.getResourceId("a_file_inside_my_lib_res");
}
}
Then, from the app that uses the lib, I have to pass the context,
public class MyActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
MyLibClass a = new MyLibClass(new MyContext(this));
}
}
MyContext, MyLibClass, and a_file_inside_my_lib_res, they all live inside the library project.
I hope it helps.
I am creating a library project for a number of android apps.
The apps all have some common functionality that I wish to include in the library project but the library project functions require use of application specific constants
So I am looking for a way to provide the library functions with the names of the constants and allow each app to define them
An example of a specific app constant and how it is used within the library project
public class AppConstants {
public static final long APP_ID = 6;//Needs to be set for each app
}
public static long getCurrentAppId(Context context) {
return getLongPreference(context, CURRENT_APP_ID_KEY, AppConstants.APP_ID);
}
This is just one example of approximately 60 constants that need to be defined for each app for a large number of library functions
Obviously I would normally just import/include the project specific app_constants.java file but this is not possible in the library project files as it hasn't got a clue about the specific applications (rightly so)
So what is the best way to have each specific app override the constants?
Update
I took a long time deciding on which of the superb answers I have been provided with best suited my needs (Thanks everyone) In the end I chose the xml solution. I don't particularly like it because it clutters up my apps resources and I did seriously consider using the interface solution but the xml solution does work nicely
Option #1
Extend your AppConstants class in each project
Better Option#2
Use XML resources to define the constants
<?xml version="1.0" encoding="utf-8"?>
<resources>
<item type="integer" name="app_id" format="integer">6</item>
</resources>
then you can retrieve them by
Context.getResources().getInteger(R.integer.app_id);
add the xml file to your resources in each project with only the values you need different
I don't know of a great schema to do that but it would certainly work this way:
define some base class in your library
// class, enum or whatever you want it to be.
class BaseConstants {
// use some real singleton instead
public static final BaseConstants instance = new BaseConstants();
// define those values - sadly static inheritance does not work
private static final int APP_ID = 0;
private static final int CURRENT_APP_ID_KEY = 24;
// so we have to do that via methods
protected int getAppId() {
return APP_ID;
}
protected int getAppIdKey() {
return CURRENT_APP_ID_KEY;
}
}
let each Activity that wants something custom implement that
class App1Constants extends BaseConstants {
public static final App1Constants instance = new App1Constants();
private final static int APP_ID = 1;
// want a different APP_ID here.
protected int getAppId() {
return APP_ID;
}
// getAppIdKey not implemented here, uses default
}
Use that class as context to the constants for your library
class Library {
public static long getCurrentAppId(Context context, BaseConstants settings) {
return getLongPreference(context, settings.getAppIdKey(), settings.getAppId());
}
}
Activities would be like so
class myActivity extends Activity {
// each Activity can implement it's own constants class and overwrite only some values
private static final BaseConstants CONSTANTS = App1Constants.instance;
private void whatever() {
long appId = Library.getCurrentAppId(this, CONSTANTS);
}
}
class myActivity2 extends Activity {
// or could just use the default ones
private static final BaseConstants CONSTANTS = BaseConstants.instance;
private void whatever() {
long appId = Library.getCurrentAppId(this, CONSTANTS);
}
}
That schema is kind of ugly but it would work at least
Define them as enum's in your library project, like
public enum Planet { MERCURY, VENUS, MARS }
Android proper takes another approach, the dreaded constant interface, like,
interface Planets {
static final int MERCURY = 1;
static final int VENUS = 2;
...
}
However, this is a well-known Java anti-pattern (constant interface, and is covered in detail in Effective Java, I quote,
The constant interface pattern is a poor use of interfaces. That a
class uses some constants internally is an implementation detail.
Implementing a constant interface causes this implementation detail to
leak into the class’s exported API. It is of no consequence to the
users of a class that the class implements a constant interface. In
fact, it may even confuse them. Worse, it represents a commitment: if
in a future release the class is modified so that it no longer needs
to use the constants, it still must implement the interface to ensure
binary compatibility. If a nonfinal class implements a constant
interface, all of its subclasses will have their namespaces polluted
by the constants in the interface.
If you need the constants to have int values for some reason, and calling toString() on the enum isn't sufficient, you can give the enum's a extra information like,
public enum ZipCode {
LYNNWOOD(98036), SAN_JOSE(95112), ...;
private int zipCode;
private ZipCode(int zipCode) { this.zipCode = zipCode; }
public int getZipCode() { return zipCode; }
}
Note that enum's are slightly less performing than integer constants, but from a code organization and clarity perspective they are far superior.