LiveData Obserever는 첫 번째 값만 잡습니다.

Firebase 데이터베이스에서 문제 목록을 얻고 LiveData을 반환합니다. 코드 내 활동의LiveData Obserever는 첫 번째 값만 잡습니다.

fun getAllIssues(): MutableLiveData<IssueEntity> { 
    val issues: MutableLiveData<IssueEntity> = MutableLiveData() 
    val issuesReference = FirebaseDatabase.getInstance().reference.child("issues") 
    issuesReference.addValueEventListener(object : ValueEventListener { 
     override fun onCancelled(p0: DatabaseError?) { 

     } 

     override fun onDataChange(snapshot: DataSnapshot?) { 
      if (snapshot == null) { 
       return 
      } 
      snapshot.children.forEach({ 
       val issueMessage = it.child("message").value.toString() 
       val issueTitle = it.child("title").value.toString() 
       val issueOwner = it.child("owner").value.toString() 

       issues.postValue(IssueEntity(issueTitle, issueMessage, issueOwner)) 
      }) 
     } 
    }) 
    return issues 
}

override fun onCreate(savedInstanceState: Bundle?) { 
    super.onCreate(savedInstanceState) 
    setContentView(R.layout.activity_all_issues) 
    val issues: MutableList<IssueEntity> = mutableListOf() 
    issuesList.adapter = IssuesAdapter(issues) 
    IssueRepository().getAllIssues().observe(this, Observer { 
     if (it != null) { 
      issues.add(it) 
      val issuesAdapter = issuesList.adapter as IssuesAdapter 
      issuesAdapter.notifyDataSetChanged() 
     } 
    }) 
}

그러나 관찰자는 첫 번째 값을 가져옵니다. 이유를 말해 주실 수 있습니까?

출처

2017-12-21 LeShChEnKoUa