Question

这不是我的代码，但我正在使用包含两个活动和下拉菜单的应用程序。您可以通过下拉列表在两个活动之间导航。我的目标是删除其中一个活动和下拉菜单。我所完成的只是从下拉菜单中删除活动，以便默认为另一个，所以现在我需要删除下拉菜单。但是，由于显示的活动是由下拉列表定义的，如果我尝试删除下拉列表，它将只绘制一个空白页面，仅显示操作栏。根据这段代码，任何人都有可能的解决方案吗？

＆＃13;

template<class ForwardIt, class T>
ForwardIt upper_bound(ForwardIt first, ForwardIt last, const T& value)
{
    ForwardIt it;
    typename std::iterator_traits<ForwardIt>::difference_type count, step;
    count = std::distance(first,last);

    while (count > 0) {
        it = first; 
        step = count / 2; 
        std::advance(it, step);
        if (!(value < *it)) {
            first = ++it;
            count -= step + 1;
        } else count = step;
    }
    return first;
}

＆＃13;

import android.annotation.TargetApi;
import android.app.ActionBar;
import android.net.Uri;
import android.os.Bundle;
import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.support.v4.app.DialogFragment;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ArrayAdapter;

public class MainActivity extends FragmentActivity implements
		ActionBar.OnNavigationListener {
	
	protected final String LOG = ".MainActivity";
	
	/**
	 * The serialization (saved instance state) Bundle key representing the
	 * current dropdown position.
	 */
	private static final String STATE_SELECTED_NAVIGATION_ITEM = "selected_navigation_item";

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);

		// Set up the action bar to show a dropdown list.
		final ActionBar actionBar = getActionBar();
		actionBar.setDisplayShowTitleEnabled(false);
		actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_LIST);
		actionBar.setDisplayShowHomeEnabled(true);
		actionBar.setIcon(R.drawable.ic_launcher);

		// Set up the dropdown list navigation in the action bar.
		actionBar.setListNavigationCallbacks(
		// Specify a SpinnerAdapter to populate the dropdown list.
				new ArrayAdapter<String>(getActionBarThemedContextCompat(),
						android.R.layout.simple_list_item_1,
						android.R.id.text1, new String[] {
								//getString(R.string.title_section_recent),
								getString(R.string.title_section_all), }), this);
		
		/**if(!getPreferences(Context.MODE_PRIVATE).getBoolean("disclaimer_accepted", false)) {
			DialogFragment dialog = new DisclaimerDialogFragment();
			dialog.show(getSupportFragmentManager(), "DisclaimerDialogFragment");
		}**/
	}

	/**
	 * Backward-compatible version of {@link ActionBar#getThemedContext()} that
	 * simply returns the {@link android.app.Activity} if
	 * <code>getThemedContext</code> is unavailable.
	 */
	@TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH)
	private Context getActionBarThemedContextCompat() {
		if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
			return getActionBar().getThemedContext();
		} else {
			return this;
		}
	}

	@Override
	public void onRestoreInstanceState(Bundle savedInstanceState) {
		// Restore the previously serialized current dropdown position.
		if (savedInstanceState.containsKey(STATE_SELECTED_NAVIGATION_ITEM)) {
			getActionBar().setSelectedNavigationItem(
					savedInstanceState.getInt(STATE_SELECTED_NAVIGATION_ITEM));
		}
	}
	
	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
	}
	
	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
		switch (item.getItemId()) {
		case R.id.action_view_source:
			Intent i2 = new Intent(Intent.ACTION_VIEW);
			i2.setData(Uri.parse(this.getString(R.string.url_source)));
			this.startActivity(i2);
			return true;

		case R.id.action_view_translation:
			Intent i3 = new Intent(Intent.ACTION_VIEW);
			i3.setData(Uri.parse(this.getString(R.string.url_translation)));
			this.startActivity(i3);
			return true;
			
		case R.id.action_view_bugs:
			Intent i4 = new Intent(Intent.ACTION_VIEW);
			i4.setData(Uri.parse(this.getString(R.string.url_bugs)));
			this.startActivity(i4);
			return true;
			
		default:
			return super.onOptionsItemSelected(item);
		}
	}


	@Override
	public void onSaveInstanceState(Bundle outState) {
		// Serialize the current dropdown position.
		outState.putInt(STATE_SELECTED_NAVIGATION_ITEM, getActionBar()
				.getSelectedNavigationIndex());
	}

	@Override
	public boolean onNavigationItemSelected(int position, long id) {
		// When the given dropdown item is selected, show its contents in the
		// container view.

		Fragment fragment = null;
		switch(position) {
		case 0:
			fragment = new AllTasksListFragment();
			break;
		case 1:
			//fragment = new RecentTaskListFragment();
			break;
		}

		getSupportFragmentManager().beginTransaction()
				.replace(R.id.container, fragment).commit();
		return true;
	}
}

＆＃13;

Answer 1

因为您的所有活动都显示片段。并且在onNavigationItemSelected期间选择片段。如果没有调用，那么你永远不会设置默认片段。因此，在onCreate中，添加一个事务来添加要保留的片段。然后你可以杀掉下拉列表。

为什么删除此下拉菜单会破坏此应用程序？

1 个答案: