如何解决通知中的意图未正确发送到其他活动
我正在尝试在通知的 Intent 中添加额外内容,以便打开 ChatActivity 并与向我发送消息的用户进行对话。我在 NotificationsListener 上传递的用户不为空。问题是我一直收到这个错误,无论我尝试什么其他调整:
2021-04-27 21:46:57.679 13553-13553/com.example.videomeeting E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.videomeeting,PID: 13553
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.videomeeting/com.example.videomeeting.activities.ChatActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String com.example.videomeeting.models.User.getUserName()' on a null object reference
at android.app.ActivityThread.performlaunchActivity(ActivityThread.java:3431)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3595)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7660)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String com.example.videomeeting.models.User.getUserName()' on a null object reference
at com.example.videomeeting.activities.ChatActivity.onCreate(ChatActivity.java:108)
at android.app.Activity.performCreate(Activity.java:8000)
at android.app.Activity.performCreate(Activity.java:7984)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
at android.app.ActivityThread.performlaunchActivity(ActivityThread.java:3404)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3595)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7660)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
代码如下:
NotificationsListener.java
@Override
public void onMessageReceived(@NonNull RemoteMessage remoteMessage) {
super.onMessageReceived(remoteMessage);
Intent activityIntent = new Intent(this,ChatActivity.class);
FirebaseDatabase.getInstance().getReference(KEY_COLLECTION_USERS)
.child(remoteMessage.getData().get(KEY_USER_ID))
.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot snapshot) {
user = snapshot.getValue(User.class);
}
@Override
public void onCancelled(@NonNull DatabaseError error) { }
});
activityIntent.putExtra(Constants.INTENT_USER,user);
activityIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK |Intent.FLAG_ACTIVITY_CLEAR_TASK);
PendingIntent contentIntent = PendingIntent.getActivity(
this,activityIntent,FLAG_UPDATE_CURRENT
);
ChatActivity.java
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_chat);
processExTradata();
//Toolbar
Toolbar toolbar = findViewById(R.id.toolbar);
toolbar.setTitle("");
setSupportActionBar(toolbar);
TextView usernameTV = findViewById(R.id.usernameTV);
usernameTV.setText(remoteUser.getUserName()); //ERROR LINE
@Override
protected void onResume() {
super.onResume();
processExTradata();
}
@Override
public void onNewIntent(Intent intent) {
super.onNewIntent(intent);
setIntent(intent);
processExTradata();
}
private void processExTradata(){
remoteUser = (User) getIntent().getSerializableExtra(INTENT_USER);
}
我已经检查过来自 NotificationsListener 的 Intent 的额外内容是否为空,而事实并非如此。一定有我没有看到的细节。感谢您抽出宝贵时间。
解决方法
错误信息明确指出 remoteUser 尚未初始化或为空,您需要检查 processExtraData() 方法正在接收哪些数据和
如果 (User) getIntent().getSerializableExtra(INTENT_USER) 没有返回用户,那么问题出在 NotificationsListener 类中
,首先,确保您传递给活动的用户不为空。我认为 onDataChange
在您将用户作为额外传递后会触发。我认为它可能对您有所帮助,如果没有,请查看 this 和 this。
谢谢你们,我只是在 onDataChange 中跟踪用户的值,由于他的异步性,这是不正确的。我做了这个修复以避免空值:
while(!isFound) {
FirebaseDatabase.getInstance().getReference(KEY_COLLECTION_USERS)
.child(remoteMessage.getData().get(KEY_USER_ID))
.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot snapshot) {
user = snapshot.getValue(User.class);
isFound = true;
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
}
});
}
再次感谢。真的很感谢?
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