Java 如何从片段在活动中设置公共文本视图?
我想从片段设置活动中textview的文本。我就是这样做的 MainActivity.javaJava 如何从片段在活动中设置公共文本视图?,java,android,android-fragments,android-activity,Java,Android,Android Fragments,Android Activity,我想从片段设置活动中textview的文本。我就是这样做的 MainActivity.java public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener { public TextView textViewNotification; @Override protected void onCreate(Bund
public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {
public TextView textViewNotification;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
NavigationView navigationView = findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
textViewNotification = (TextView) MenuItemCompat.getActionView(navigationView.getMenu().findItem(R.id.nav_notification));
}
}
public class HomeFragment extends Fragment {
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
((MainActivity)getActivity()).getSupportActionBar().setTitle("PIT IAI & FIP Regional");
ViewGroup root = (ViewGroup) inflater.inflate(R.layout.fragment_home, container, false);
MainActivity activity = (MainActivity) getActivity();
activity.notification.setText("This is a test"); // => got error here.
return root;
}
}
HomeFragment.java
public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {
public TextView textViewNotification;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
NavigationView navigationView = findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
textViewNotification = (TextView) MenuItemCompat.getActionView(navigationView.getMenu().findItem(R.id.nav_notification));
}
}
public class HomeFragment extends Fragment {
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
((MainActivity)getActivity()).getSupportActionBar().setTitle("PIT IAI & FIP Regional");
ViewGroup root = (ViewGroup) inflater.inflate(R.layout.fragment_home, container, false);
MainActivity activity = (MainActivity) getActivity();
activity.notification.setText("This is a test"); // => got error here.
return root;
}
}
但它不起作用。这是我得到的错误:
android.content.res.Resources$NotFoundException: String resource ID #0x1
at android.content.res.Resources.getText(Resources.java:348)
at android.widget.TextView.setText(TextView.java:5846)
如何从片段中获取和设置活动的公共属性?不可能吗?请提供帮助。Henry Gunawan您的主要活动没有任何名为notification的公共字段,您实际上将其命名为textViewNotification 此外,我在您的代码中看到了一些不好的做法
假设您希望基于某个操作将文本发送到活动 您可以使用一个接口,首先在片段中创建一个公共接口,并在其中添加一个方法,该方法接受一个字符串参数
public interface CommunicateWithActivity{
void onCommunicate(String s)
}
,声明CommunicateWithActivity类型的全局变量mListener
private CommunicateWithActivity mListener;
然后覆盖转速表和内部尝试/捕捉块
@Override
public void onAttach(@NonNull Context context) {
super.onAttach(context);
try {
mListener = (CommunicateWithActivity) context;
} catch (ClassCastException e) {
throw new ClassCastException(context.toString() + "CommunicateWithActivity implementation in Activity is required");
}
}
然后在活动中实现接口,在活动中重写“oncommunicate(String s)”方法,您将在方法中获得字符串
@Override
public void onCommunicate(String s) {
//do whatever you want
}
将“thisatest”移动到stringresources并用R.string替换它。testIt最好从构造函数获取它。这样,用户就可以在同一个活动中使用片段的多个实例。这种情况很少见,但易于阅读和实现。