bug: notifyListeners() only works for the first call

[kofoeddk]

Bug Report

notifyListeners() in Plugin.java only works the first time for retained event arguments due to insufficient empty state check.

Capacitor Version

npx cap doctor output:
💊 Capacitor Doctor 💊

Latest Dependencies:

@capacitor/cli: 1.5.0

@capacitor/core: 1.5.0

@capacitor/android: 1.5.0

@capacitor/ios: 1.5.0

Installed Dependencies:

@capacitor/cli 1.4.0

@capacitor/core 1.4.0

@capacitor/android 1.4.0

@capacitor/ios 1.4.0

Affected Platform(s)

• Android
• iOS
• Electron
• Web

Current Behavior

From a plugin, notify listener:
notifyListeners("myListener", jsObjInstance, true)

.. and from TypeScript component:

listener = Plugin.addListener('myListener'), (response) => {
    listener.remove();
    // do something with response
}

This works perfectly for the first call.

Expected Behavior

I would expect it to work for subsequent calls as well.

Sample Code or Sample Application Repo

Reproduction Steps

See Current Behavior

Resolutiuon

Add isEmpty() checks for lists instead of only doing null-checks.

git diff output:

diff --git a/android/capacitor/src/main/java/com/getcapacitor/Plugin.java b/android/capacitor/src/main/java/com/getcapacitor/Plugin.java
index cedd7c7..3caeaed 100644
--- a/android/capacitor/src/main/java/com/getcapacitor/Plugin.java
+++ b/android/capacitor/src/main/java/com/getcapacitor/Plugin.java
@@ -300,7 +300,7 @@ public class Plugin {
    */
   private void addEventListener(String eventName, PluginCall call) {
     List<PluginCall> listeners = eventListeners.get(eventName);
-    if (listeners == null) {
+    if (listeners == null || listeners.isEmpty()) {
       listeners = new ArrayList<PluginCall>();
       eventListeners.put(eventName, listeners);
 
@@ -335,7 +335,7 @@ public class Plugin {
   protected void notifyListeners(String eventName, JSObject data, boolean retainUntilConsumed) {
     Log.v(getLogTag(), "Notifying listeners for event " + eventName);
     List<PluginCall> listeners = eventListeners.get(eventName);
-    if (listeners == null) {
+    if (listeners == null || listeners.isEmpty()) {
       Log.d(getLogTag(), "No listeners found for event " + eventName);
       if (retainUntilConsumed) {
         retainedEventArguments.put(eventName, data);

[kofoeddk]

Actually, this issue has an iOS counterpart that was fixed almost the same way:
#2094

[kofoeddk]

Added PR: #2408

[ionitron-bot]

Thanks for the issue! This issue is being locked to prevent comments that are not relevant to the original issue. If this is still an issue with the latest version of Capacitor, please create a new issue and ensure the template is fully filled out.