java - 用ProgressBar替换ProgressDialog，一半时间不显示

Question

标题不太好，但我正在 Android 应用程序中用 ProgressBar 替换 ProgressDialog 。在我的 ProjectsFragment 类中实现它后，我运行该应用程序，并在应用程序从我的数据库加载数据时看到默认的 ProgressBar 加载。这很好用。然后，我替换了 ProjectViewActivity 中的 ProgressDialog，并且不再显示任何 ProgressBars。我无法判断它们是否有效，只是没有显示，或者我是否通过将 ProgressBar 添加到父 Activity 而破坏了它。我的另一个想法是，也许应用程序已经缓存了数据，并且加载速度太快，以至于 ProgressBar 甚至没有出现，但删除缓存和所有应用程序数据后，它仍然不会显示。

这是我在 ProjectsFragment 类中运行的代码:

loading = new ProgressBar(getActivity());
public void loadProjects() {
    loading.setVisibility(View.VISIBLE);
    db.collection("users").document(user.getUid()).collection("projects").get() //Get all projects from selected user
        .addOnSuccessListener(new OnSuccessListener < QuerySnapshot > () {
            @Override
            public void onSuccess(QuerySnapshot queryDocumentSnapshots) {
                projects.clear(); //Clear before reloading
                for (QueryDocumentSnapshot documentSnapshot: queryDocumentSnapshots) {
                    projects.add(documentSnapshot.toObject(ProjectItem.class));
                }
                refreshRecycler();
            }
        });
}

public void refreshRecycler() {
        adapter = new DashboardProjectAdapter(projects, getContext()); //Create adapter with list of projects
        recyclerView.setAdapter(adapter); //Assign adapter to recycler view
        adapter.setOnItemClickListener(new DashboardProjectAdapter.OnItemClickListener() {
            @Override
            public void onItemClick(int position) {
                String projectID;
                projectID = projects.get(position).getProjectID();
                String projectName;
                projectName = projects.get(position).getProjectName();
                Intent openProjectView = new Intent(getActivity().getApplicationContext(), ProjectViewActivity.class); //?
                openProjectView.putExtra("projectID", projectID);
                openProjectView.putExtra("projectName", projectName);
                startActivity(openProjectView);
            }
        });
        loading.setVisibility(View.GONE);

这是我来自 ProjectViewActivity 的代码，我已经启动了两次，然后它没有显示任何地方(很抱歉添加的代码长度，我只是不确定我哪里出错了):

ProgressBar loading;
public void loadTasks() {
    loading.setVisibility(View.VISIBLE);
    //Get tasks from database and load into ArrayList
    db.collection("users").document(user.getUid()).collection("projects").document(projectID).collection("tasks").get()
        .addOnSuccessListener(new OnSuccessListener < QuerySnapshot > () {
            @Override
            public void onSuccess(QuerySnapshot queryDocumentSnapshots) {
                //Clear list
                allTasks.clear();
                for (QueryDocumentSnapshot documentSnapshot: queryDocumentSnapshots) {
                    allTasks.add(documentSnapshot.toObject(TaskItem.class));
                }
                //Clear lists
                tasksToDo.clear();
                tasksInProgress.clear();
                tasksInReview.clear();
                tasksComplete.clear();
                //Sort tasks into respective lists
                for (TaskItem task: allTasks) {
                    switch (task.getStatus()) {
                        case 0:
                            tasksToDo.add(task);
                            break;
                        case 1:
                            tasksInProgress.add(task);
                            break;
                        case 2:
                            tasksInReview.add(task);
                            break;
                        case 3:
                            tasksComplete.add(task);
                            break;
                        default:
                            Toast.makeText(ProjectViewActivity.this, "A database error has occurred, please contact a Developer", Toast.LENGTH_LONG).show();
                    }
                }
                setupAdapters();
                loading.setVisibility(View.GONE);
                displayToDo();
            }
        });
}

//This is the method called from the ProjectReviewViewAdapter after a tasked is marked complete
public void loadTasksReview() {
        loading.setVisibility(View.VISIBLE);
        //Get tasks from database and load into ArrayList
        db.collection("users").document(user.getUid()).collection("projects").document(projectID).collection("tasks").get()
            .addOnSuccessListener(new OnSuccessListener < QuerySnapshot > () {
                @Override
                public void onSuccess(QuerySnapshot queryDocumentSnapshots) {
                    //Clear list
                    allTasks.clear();
                    for (QueryDocumentSnapshot documentSnapshot: queryDocumentSnapshots) {
                        allTasks.add(documentSnapshot.toObject(TaskItem.class));
                    }
                    //Clear lists
                    tasksToDo.clear();
                    tasksInProgress.clear();
                    tasksInReview.clear();
                    tasksComplete.clear();
                    //Sort tasks into respective lists
                    for (TaskItem task: allTasks) {
                        switch (task.getStatus()) {
                            case 0:
                                tasksToDo.add(task);
                                break;
                            case 1:
                                tasksInProgress.add(task);
                                break;
                            case 2:
                                tasksInReview.add(task);
                                break;
                            case 3:
                                tasksComplete.add(task);
                                break;
                            default:
                                Toast.makeText(ProjectViewActivity.this, "A database error has occurred, please contact a Developer", Toast.LENGTH_LONG).show();
                        }
                    }
                    setupAdapters();
                    loading.setVisibility(View.GONE);
                    Snackbar snackbar = Snackbar.make(layout, "Task accepted and moved to complete.", Snackbar.LENGTH_LONG);
                    snackbar.show();
                    displayForReview();
                }
            });

感谢任何帮助，如果您需要，我可以解释我的代码的任何步骤。同样，它在 Android Studio 中没有显示任何错误。

Answer 1

您首先需要将进度条添加到您的主布局或您希望它出现的布局中

  main.addView(loading);

如果您想编辑其布局参数(例如位置)，您还可以设置布局参数