Handle all observable errors gracefully

Author: niranjan94

app/src/main/kotlin/com/njlabs/showjava/activities/decompiler/DecompilerActivity.kt

@@ -22,7 +22,6 @@ import android.annotation.SuppressLint
 import android.app.ActivityOptions
 import android.content.Intent
 import android.graphics.Typeface
-import android.graphics.drawable.Drawable
 import android.os.Build
 import android.os.Bundle
 import android.text.Spannable
@@ -46,7 +45,6 @@ import com.njlabs.showjava.decompilers.BaseDecompiler.Companion.isAvailable
 import com.njlabs.showjava.utils.ktx.sourceDir
 import com.njlabs.showjava.utils.ktx.toBundle
 import io.reactivex.Observable
-import io.reactivex.ObservableEmitter
 import io.reactivex.android.schedulers.AndroidSchedulers
 import io.reactivex.schedulers.Schedulers
 import kotlinx.android.synthetic.main.activity_decompiler.*
@@ -121,8 +119,8 @@ class DecompilerActivity : BaseActivity() {
         }
 
         disposables.add(
-            Observable.create { emitter: ObservableEmitter<Drawable> ->
-                emitter.onNext(packageInfo.loadIcon(context))
+            Observable.fromCallable {
+                packageInfo.loadIcon(context)
             }
                 .subscribeOn(Schedulers.io())
                 .observeOn(AndroidSchedulers.mainThread())
@@ -196,9 +194,11 @@ class DecompilerActivity : BaseActivity() {
 
         BaseDecompiler.start(inputMap)
 
-        firebaseAnalytics.logEvent(Constants.EVENTS.SELECT_DECOMPILER, hashMapOf(
-            FirebaseAnalytics.Param.VALUE to decompiler
-        ).toBundle())
+        firebaseAnalytics.logEvent(
+            Constants.EVENTS.SELECT_DECOMPILER, hashMapOf(
+                FirebaseAnalytics.Param.VALUE to decompiler
+            ).toBundle()
+        )
 
         firebaseAnalytics.logEvent(Constants.EVENTS.DECOMPILE_APP, inputMap.toBundle())
 

app/src/main/kotlin/com/njlabs/showjava/activities/explorer/navigator/NavigatorActivity.kt

@@ -104,7 +104,11 @@ class NavigatorActivity : BaseActivity() {
         disposables.add(navigationHandler.loadFiles(startDirectory)
             .subscribeOn(Schedulers.io())
             .observeOn(AndroidSchedulers.mainThread())
-            .doOnError { Timber.e(it) }
+            .onErrorReturn {
+                Timber.e(it)
+                Toast.makeText(context, R.string.errorLoadingFiles, Toast.LENGTH_SHORT).show()
+                ArrayList()
+            }
             .subscribe {
                 updateList(it)
                 swipeRefresh.isRefreshing = false
@@ -226,7 +230,12 @@ class NavigatorActivity : BaseActivity() {
         return currentDirectory?.canonicalPath == selectedApp?.sourceDirectory?.canonicalPath
     }
 
-    private fun shareArchive(file: File) {
+    private fun shareArchive(file: File?) {
+        if (file == null) {
+            Toast.makeText(context, R.string.genericError, Toast.LENGTH_SHORT).show()
+            return
+        }
+
         dismissProgressDialog()
         val shareIntent = Intent()
         shareIntent.action = Intent.ACTION_SEND
@@ -277,7 +286,10 @@ class NavigatorActivity : BaseActivity() {
                 )
                     .subscribeOn(Schedulers.io())
                     .observeOn(AndroidSchedulers.mainThread())
-                    .doOnError { Timber.e(it) }
+                    .onErrorReturn {
+                        Timber.e(it)
+                        null
+                    }
                     .subscribe {
                         sourceArchive = it
                         shareArchive(it)

app/src/main/kotlin/com/njlabs/showjava/activities/explorer/viewer/CodeViewerActivity.kt

@@ -28,14 +28,11 @@ import android.view.MenuItem
 import android.view.View
 import com.njlabs.showjava.R
 import com.njlabs.showjava.activities.BaseActivity
-import com.njlabs.showjava.utils.rx.ProcessStatus
 import com.njlabs.showjava.utils.views.CodeView
 import io.reactivex.Observable
-import io.reactivex.ObservableEmitter
 import io.reactivex.android.schedulers.AndroidSchedulers
 import io.reactivex.schedulers.Schedulers
 import kotlinx.android.synthetic.main.activity_code_viewer.*
-import timber.log.Timber
 import java.io.File
 
 class CodeViewerActivity : BaseActivity(), CodeView.OnHighlightListener {
@@ -105,9 +102,11 @@ class CodeViewerActivity : BaseActivity(), CodeView.OnHighlightListener {
             loadFile(file)
                 .subscribeOn(Schedulers.io())
                 .observeOn(AndroidSchedulers.mainThread())
-                .doOnError { error -> Timber.e(error) }
-                .subscribe { status ->
-                    codeView.setCode(status.result)
+                .onErrorReturn {
+                    it.localizedMessage
+                }
+                .subscribe { fileContent ->
+                    codeView.setCode(fileContent)
                         .setLanguage(language)
                         .setWrapLine(wrapLine)
                         .setDarkMode(invertColors)
@@ -120,10 +119,9 @@ class CodeViewerActivity : BaseActivity(), CodeView.OnHighlightListener {
         )
     }
 
-    private fun loadFile(fileToLoad: File): Observable<ProcessStatus<String>> {
-        return Observable.create { emitter: ObservableEmitter<ProcessStatus<String>> ->
-            emitter.onNext(ProcessStatus(fileToLoad.readText()))
-            emitter.onComplete()
+    private fun loadFile(fileToLoad: File): Observable<String> {
+        return Observable.fromCallable {
+            fileToLoad.readText()
         }
     }
 

app/src/main/kotlin/com/njlabs/showjava/activities/landing/LandingActivity.kt

@@ -172,7 +172,10 @@ class LandingActivity : BaseActivity() {
         disposables.add(landingHandler.loadHistory()
             .subscribeOn(Schedulers.io())
             .observeOn(AndroidSchedulers.mainThread())
-            .doOnError { Timber.e(it) }
+            .onErrorReturn {
+                Timber.e(it)
+                ArrayList()
+            }
             .subscribe {
                 historyItems = it
                 swipeRefresh.isRefreshing = false

app/src/main/res/values/strings.xml

@@ -174,4 +174,6 @@
     <string name="instanceId">(ID: <xliff:g example="abc134_GTF" id="instanceIdString">%1$s</xliff:g>)</string>
     <string name="onlyPositiveIntegersAllowed">Only positive integers are allowed</string>
     <string name="errorLoadingInputFile">Error loading input file</string>
+    <string name="genericError">An unexpected error occurred</string>
+    <string name="errorLoadingFiles">An error occurred while loading files</string>
 </resources>