Android 单击菜单项时无法显示片段

单击菜单项时，我很难在容器中显示片段。下面是我的代码

我试着做

ft.show（）

inside onMenuItem单击登录菜单项，但它不工作，我不知道我做错了什么，因为我既没有收到任何错误，也没有应用程序崩溃。附在选项卡上的片段工作正常，显示良好。只是当我试图在容器中加载一个片段时，当菜单项被点击时，什么都没有发生。请给我指出一个正确的方向，让我知道我做错了什么

public class HomeActivity extends SherlockFragmentActivity {

public SherlockFragment fragment;
FragmentTransaction ft;
public static Context appContext;
ActionBar actionbar;
String mCurFilter;
LoginScreenFragment loginFragment;

/** Called when the activity is first created. */
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.home);
    appContext = getApplicationContext();
    actionbar = getSupportActionBar();
    actionbar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

    ActionBar.Tab HomeTab = actionbar.newTab().setText("Home");
    ActionBar.Tab CartTab = actionbar.newTab().setText("Cart");
    ActionBar.Tab myTab = actionbar.newTab().setText("MyFragment");
    ActionBar.Tab moreTab = actionbar.newTab().setText("More...");

    HomeFragment homeFragment = new HomeFragment();
    CartFragment cartFragment = new CartFragment();
    MyFragment myFragment = new MyFragment();
    MoreFragment moreFragment = new MoreFragment();
    loginFragment = new LoginScreenFragment();

    HomeTab.setTabListener(new MyTabsListener(homeFragment));
    CartTab.setTabListener(new MyTabsListener(cartFragment));
    myTab.setTabListener(new MyTabsListener(myFragment));
    moreTab.setTabListener(new MyTabsListener(moreFragment));

    actionbar.addTab(HomeTab);
    actionbar.addTab(CartTab);
    actionbar.addTab(myTab);
    actionbar.addTab(moreTab);

    ft = getSupportFragmentManager().beginTransaction();
    ft.add(R.id.fragment_container, homeFragment);
    ft.show(homeFragment);
    ft.add(R.id.fragment_container, cartFragment);
    ft.hide(cartFragment);
    ft.add(R.id.fragment_container, myFragment);
    ft.hide(myFragment);
    ft.add(R.id.fragment_container, moreFragment);
    ft.hide(moreFragment);
    ft.add(R.id.fragment_container, loginFragment);
    ft.hide(loginFragment);
    ft.commit();
}

@Override
protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    outState.putInt("tab", getSupportActionBar()
            .getSelectedNavigationIndex());
    System.out.println("onSaveInstanceState");
}

@Override
public boolean onCreateOptionsMenu(final Menu menu) {

    MenuItem item = menu.add("Search");
    item.setIcon(android.R.drawable.ic_menu_search);
    item.setShowAsAction(MenuItem.SHOW_AS_ACTION_ALWAYS);
    View searchView = SearchViewCompat.newSearchView(this);
    if (searchView != null) {
        SearchViewCompat.setOnQueryTextListener(searchView,
                new OnQueryTextListenerCompat() {
            @Override
            public boolean onQueryTextChange(String newText) {
                mCurFilter = !TextUtils.isEmpty(newText) ? newText : null;
                return true;
            }
        });
        item.setActionView(searchView);
    }
    MenuItem loginItem = menu.add("Login");
    loginItem.setTitle("Login");
    loginItem.setShowAsAction(MenuItem.SHOW_AS_ACTION_ALWAYS);
    loginItem.setOnMenuItemClickListener(new OnMenuItemClickListener(){

        @Override
        public boolean onMenuItemClick(MenuItem item) {
//I wanted to show "loginFragment" when the Login button is clicked.But unfortunately its not showing up.Also the application is not giving any errors or crashing
            ft.show(loginFragment);
            return false;
        }

    });
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    int itemId = item.getItemId();
    if (itemId == R.id.menuitem_home) {
        Toast.makeText(appContext, "Home", Toast.LENGTH_SHORT).show();
        return true;
    } else if (itemId == R.id.menuitem_shop) {
        Toast.makeText(appContext, "Shop", Toast.LENGTH_SHORT).show();
        return true;
    } else if (itemId == R.id.menuitem_cart) {
        Toast.makeText(appContext, "Cart", Toast.LENGTH_SHORT).show();
        return true;
    } else if (itemId == R.id.menuitem_my) {
        Toast.makeText(appContext, "My", Toast.LENGTH_SHORT).show();
        return true;
    } else if (itemId == R.id.menuitem_more) {
        Toast.makeText(appContext, "More...", Toast.LENGTH_SHORT).show();
        return true;
    }
    return false;
}

static class MyTabsListener implements ActionBar.TabListener {
    public SherlockFragment fragment;

    public MyTabsListener(SherlockFragment fragment) {
        this.fragment = fragment;
    }

    @Override
    public void onTabReselected(Tab tab, FragmentTransaction ft) {
        System.out.println("TabReselected " + tab.getPosition());
    }

    @Override
    public void onTabSelected(Tab tab, FragmentTransaction ft) {
        System.out.println("TabSelected " + tab.getPosition());
        ft.show(this.fragment);
    }

    @Override
    public void onTabUnselected(Tab tab, FragmentTransaction ft) {
        System.out.println("TabUnselected " + tab.getPosition());
        ft.hide(this.fragment);
    }
}
}

---

您可以尝试在单击菜单按钮时替换片段，而不是将片段添加到一个容器中并隐藏和显示它们

例如，当您单击登录按钮时

ft.replace(R.id.fragment_container, loginFragment).commit();

---

尝试一下，希望它能工作。

您应该重新开始并提交事务。尝试：

@Override
public boolean onMenuItemClick(MenuItem item) {
    ft = getSupportFragmentManager().beginTransaction();
    ft.show(loginFragment);
    ft.commit();
    return false;
}

---

你能检查一下是否真的添加了片段吗？@Swati谢谢你的回复。是的，片段被添加了。所有附在选项卡上的片段都显示出来了。只是当我执行ft.show时，没有附在任何选项卡上的loginFragment没有显示出来（loginFragment）在onMenuItemClick.ThanksThanks内点击。感谢您的回复。我尝试了这个方法，但它给我的错误是“commit ready called”。因为我已经在onCreate中调用了commit（）。只需删除那里的adding并在此处替换即可。导致该错误的原因可能是，如果您尚未删除该错误，则该错误已添加到布局中。