java - 进度条 setVisibility VISIBLE

Question

我是 JAVA 新手，所以我试图在程序员列表渲染时显示进度条可见，但进度条始终可见

公共(public)类ListActivity扩展AppCompatActivity { 私有(private)Repository存储库；

private final List<Programmer> programmers = new ArrayList<>();

private ListView listView;
private ProgressBar progressBar;


private ProgrammersListAdapter programmersListAdapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_list);

    listView = findViewById(R.id.listView);
    progressBar = findViewById(R.id.progressBar);

    progressBar.setVisibility(View.INVISIBLE);

    repository = CombinedRepository.getInstance();

    // It's important not to change reference of the list provided here. That's why it's final!
    programmersListAdapter = new ProgrammersListAdapter(this, programmers);
    listView.setAdapter(programmersListAdapter);
    refreshProgrammers();
}

void refreshProgrammers(){
    // ToDO: Change Progress bar visibility here
    progressBar.setVisibility(View.VISIBLE);
    this.programmers.clear();

    // Without notifyDataSetChanged - Listview won't know that there's been update to it's data
    this.programmersListAdapter.notifyDataSetChanged();

    repository.getProgrammers(programmers -> {
        this.programmers.clear();
        this.programmers.addAll(programmers);
        this.programmersListAdapter.notifyDataSetChanged();
    });
}

}

Answer 1

从 onCreate 中删除 progressBar.setVisibility(View.INVISIBLE); 并在 getProgrammers 的回调中进行隐藏:

repository.getProgrammers(programmers -> {
    this.programmers.clear();
    this.programmers.addAll(programmers);
    this.programmersListAdapter.notifyDataSetChanged();
    progressBar.setVisibility(View.GONE); // hide progressBar after data is loaded
});

我还建议使用View.GONE而不是View.INVISIBLE因此进度条在不可见时不会占用任何空间。