Question

TLDR：如何在Fragment中显示AlertDialog？

我创建了一个导航抽屉，随我的主页打开，该主页被写为片段。在此主页片段中创建按钮时，该按钮不会按预期显示AlertDialog。我的logcat中没有错误，所以我不确定代码的问题是什么。

MainActivity.java：

 public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {
private DrawerLayout mDrawerLayout;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    ActionBar actionbar = getSupportActionBar();
    actionbar.setDisplayHomeAsUpEnabled(true);
    actionbar.setHomeAsUpIndicator(R.drawable.ic_menu);
    mDrawerLayout = findViewById(R.id.drawer_layout);

    NavigationView navigationView = findViewById(R.id.nav_view);
    navigationView.setNavigationItemSelectedListener(this);
    displaySelectedPage(R.id.fragment_homepage);

}

public boolean onOptionsItemSelected(MenuItem menuitem) {
    switch(menuitem.getItemId()) {
        case android.R.id.home:
            mDrawerLayout.openDrawer(GravityCompat.START);
            return true;
    }
    return super.onOptionsItemSelected(menuitem);
}

private void displaySelectedPage(int itemid) {
    Fragment fragment = null;
    switch (itemid) {
        case R.id.fragment_homepage:
            fragment = new Homepage();

            break;
    }

    if (fragment != null) {
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        ft.replace(R.id.content_frame, fragment);
        ft.commit();
    }
}

public boolean onNavigationItemSelected(MenuItem item) {
    displaySelectedPage(item.getItemId());
    return true;
}

}

我认为问题在于使用AlertDialog构建器声明getActivity，主页：

 public class Homepage extends Fragment {
private AlertDialog mAlertDialog;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.fragment_home, container, false);
    Button aboutButton = (Button) v.findViewById(R.id.about_button);
    aboutButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
            builder.setTitle("About");
            builder.setMessage("Chameleon is the app for you");
            builder.setCancelable(false);
            builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {

                }
            });
            mAlertDialog = builder.show();
        }
    });
    return inflater.inflate(R.layout.fragment_home, container, false);
}




public void  onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    getActivity().setTitle("Homepage");
  }
 }

编辑：在onCreateView中用return v替换return语句修复了问题

在Fragment

0 个答案: