问题描述
我能够编写一个简单的计时器,通过一个按钮启动和重置时间。我可以在MainActivity中编写它,但是现在我只希望在一个特定的片段上编写它。我有3个导航片段。主页,历史记录和学习。
这是MainActivity中的内容
public class MainActivity extends AppCompatActivity {
private Chronometer chronometer;
private boolean running;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
BottomNavigationView navView = findViewById(R.id.nav_view);
AppBarConfiguration appBarConfiguration = new AppBarConfiguration.Builder(
R.id.navigation_home,R.id.navigation_dashboard,R.id.navigation_notifications)
.build();
NavController navController = Navigation.findNavController(this,R.id.nav_host_fragment);
NavigationUI.setupActionBarWithNavController(this,navController,appBarConfiguration);
NavigationUI.setupWithNavController(navView,navController);
chronometer = findViewById(R.id.chronometer);
}
public void startChronometer(View v) {
if(!running) {
chronometer.setBase(SystemClock.elapsedRealtime());
chronometer.start();
running = true;
((TextView)findViewById(R.id.startbutton)).setText("End");
} else {
if(running) {
chronometer.setBase(SystemClock.elapsedRealtime());
chronometer.stop();
running = false;
((TextView) findViewById(R.id.startbutton)).setText("Start");
}
}
}
}
这是空的片段代码
public class HomeFragment extends Fragment {
Chronometer chronometer;
public View onCreateView(@NonNull LayoutInflater inflater,ViewGroup container,Bundle savedInstanceState) {
Homeviewmodel homeviewmodel = viewmodelProviders.of(this).get(Homeviewmodel.class);
View root = inflater.inflate(R.layout.fragment_home,container,false);
final TextView textView = root.findViewById(R.id.text_home);
homeviewmodel.getText().observe(getViewLifecycleOwner(),new Observer<String>() {
@Override
public void onChanged(@Nullable String s) {
textView.setText(s);
}
});
return root;
}
}
感谢您的帮助,并抽出宝贵的时间阅读本文章。
解决方法
您可以将代码放入OnViewCreated
函数中。或者简单地使用名为“ root”的视图。为了更好的理解,我将名称更改为viewRoot。
当然,您需要将布局放置在片段中,而不是在活动中。
public class HomeFragment extends Fragment {
Chronometer chronometer;
public View onCreateView(@NonNull LayoutInflater inflater,ViewGroup container,Bundle savedInstanceState) {
HomeViewModel homeViewModel = ViewModelProviders.of(this).get(HomeViewModel.class);
View viewRoot = inflater.inflate(R.layout.fragment_home,container,false);
final TextView textView = viewRoot.findViewById(R.id.text_home);
homeViewModel.getText().observe(getViewLifecycleOwner(),new Observer<String>() {
@Override
public void onChanged(@Nullable String s) {
textView.setText(s);
}
});
chronometer = viewRoot.findViewById(R.id.chronometer);
//If you want to start the timer
startChronometer(viewRoot);
return root;
}
}
请注意startChronometer
,因为您致电findViewById
。您知道这些按钮的位置吗?
我添加了getView()
,因此您可以从片段本身中调用它们。
public void startChronometer(View v) {
if(!running) {
chronometer.setBase(SystemClock.elapsedRealtime());
chronometer.start();
running = true;
((TextView)getView().findViewById(R.id.startbutton)).setText("End");
} else {
if(running) {
chronometer.setBase(SystemClock.elapsedRealtime());
chronometer.stop();
running = false;
((TextView) getView().findViewById(R.id.startbutton)).setText("Start");
}
}
}
}
希望我能帮上忙。