平板电脑上没有出现溢出点

Question

由于某种原因，当我选择一个列表项时，我的主详细信息应用程序的平板电脑上没有出现溢出点，但它们却出现在我的手机上。尽管使用了必要的代码，但我不确定为什么会发生。是否有人缺少任何代码或不应该存在的代码？

MainActivity.java

public class MainActivity extends ActionBarActivity {

    private boolean mTwoPane;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        try {
            ViewConfiguration config = ViewConfiguration.get(this);
            Field menuKeyField = ViewConfiguration.class.getDeclaredField("sHasPermanentMenuKey");
            if (menuKeyField != null) {
                menuKeyField.setAccessible(true);
                menuKeyField.setBoolean(config, false);
            }
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        ActionBar actionBar = getSupportActionBar();
        actionBar.setTitle(getResources().getString(R.string.greeting));

        FragmentMainList newFragment = new FragmentMainList();
        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
        transaction.replace(R.id.master_container, newFragment);
        transaction.commit();

        if (findViewById(R.id.detail_container) != null) {
            mTwoPane = true;
        }
    }
}

活动类

public class MyProductActivity extends ActionBarActivity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.my_fragment);

        if (savedInstanceState == null) {
            FragmentProduct newFragment = new FragmentProduct();
            FragmentTransaction transaction = this.getSupportFragmentManager().beginTransaction();
            transaction.replace(R.id.detail_container, newFragment);
            transaction.commit();
        }

        ActionBar actionBar = getSupportActionBar(); 
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.my_menu, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (item.getItemId() == android.R.id.home) {
            final Intent intent = NavUtils.getParentActivityIntent(this);
            intent.addFlags(Intent.FLAG_ACTIVITY_NO_ANIMATION);
            NavUtils.navigateUpTo(this, intent);
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

片段类

public class FragmentProduct extends android.support.v4.app.Fragment {

    public FragmentProduct() {}

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.fragment_product, container, false);

        super.onCreate(savedInstanceState);
        setHasOptionsMenu(true);

        return v;
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        View v = getView();

        super.onActivityCreated(savedInstanceState);
    }

    @Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        super.onCreateOptionsMenu(menu, inflater);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (item.getItemId() == android.R.id.home) {
            final Intent intent = NavUtils.getParentActivityIntent(getActivity());
            intent.addFlags(Intent.FLAG_ACTIVITY_NO_ANIMATION);
            NavUtils.navigateUpTo(getActivity(), intent);
            return true;
        }

        int id = item.getItemId();

        if (id == R.id.action_options) {
        }

        return super.onOptionsItemSelected(item);
    }
}

Answer 1

只有没有硬件菜单按钮的设备才会显示这些点。对于具有硬件菜单按钮的设备，不会显示溢出点，因为点击菜单按钮会执行相同的操作。 更多here

编辑

如果出于某种原因你真的想展示它，你可以在你的Application.onCreate()或主（启动器）活动onCreate()中添加以下代码

// force show actionbar 'overflow' button on devices with hardware menu button
try {
    ViewConfiguration config = ViewConfiguration.get(this);
    Field menuKeyField = ViewConfiguration.class.getDeclaredField("sHasPermanentMenuKey");
    if (menuKeyField != null) {
        menuKeyField.setAccessible(true);
        menuKeyField.setBoolean(config, false);
    }
}
catch (Exception e) {
    e.printStackTrace();
}