我一直在尝试编写一个具有 ActionBar 的活动，您可以在其中选择所需的视图。我创建了一个基本活动类，其中包含大部分 ActionBar 特定代码，以扩展到导航下拉微调器中的类。这是基类的代码。
public class MainFlowActivity extends FragmentActivity implements ActionBar.OnNavigationListener {
private static final String STATE_SELECTED_NAVIGATION_ITEM = "selected_navigation_item";
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment_main);
// Set up the action bar to show a dropdown list.
final ActionBar actionBar = getActionBar();
actionBar.setDisplayShowTitleEnabled(false);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_LIST);
// Set up the dropdown list navigation in the action bar.
actionBar.setListNavigationCallbacks(
// Specify a SpinnerAdapter to populate the dropdown list.
new ArrayAdapter(getActionBarThemedContextCompat(),
android.R.layout.simple_spinner_dropdown_item,
android.R.id.text1, new String[] {
getString(R.string.title_section1),
getString(R.string.title_section2),
getString(R.string.title_section3), }), this);
}
@Override
protected void onPause() {
// TODO Auto-generated method stub
super.onPause();
}
@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 void onSaveInstanceState(Bundle outState) {
// Serialize the current dropdown position.
outState.putInt(STATE_SELECTED_NAVIGATION_ITEM, getActionBar().getSelectedNavigationIndex());
}
@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 onNavigationItemSelected(int position, long id) {
// When the given dropdown item is selected, show its contents in the
// container view.
switch (position){
case 0:
startActivity(new Intent("com.example.portarius.mainflow.ITEMLISTACTIVITY"));
return true;
case 1:
startActivity(new Intent("com.example.portarius.mainflow.TESTDUMMYLOGG"));
return true;
case 2:
startActivity(new Intent("com.example.portarius.mainflow.TESTDUMMYKARTVIEW"));
return true;
default:
return onNavigationItemSelected(position, id);
}
}
}
这是继承此类的活动之一：
/** * An activity representing a list of Items. This activity has different * presentations for handset and tablet-size devices. On handsets, the activity * presents a list of items, which when touched, lead to a * {@link ItemDetailActivity} representing item details. On tablets, the * activity presents the list of items and item details side-by-side using two * vertical panes. ** The activity makes heavy use of fragments. The list of items is a * {@link ItemListFragment} and the item details (if present) is a * {@link ItemDetailFragment}. *
* This activity also implements the required {@link ItemListFragment.Callbacks} * interface to listen for item selections. */ public class ItemListActivity extends MainFlowActivity implements ItemListFragment.Callbacks { /** * Whether or not the activity is in two-pane mode, i.e. running on a tablet * device. */ private boolean mTwoPane; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_item_list); if (findViewById(R.id.item_detail_container) != null) { // The detail container view will be present only in the // large-screen layouts (res/values-large and // res/values-sw600dp). If this view is present, then the // activity should be in two-pane mode. mTwoPane = true; // In two-pane mode, list items should be given the // 'activated' state when touched. ((ItemListFragment) getSupportFragmentManager().findFragmentById( R.id.item_list)).setActivateOnItemClick(true); } // TODO: If exposing deep links into your app, handle intents here. } /** * Callback method from {@link ItemListFragment.Callbacks} indicating that * the item with the given ID was selected. */ @Override public void onItemSelected(String id) { if (mTwoPane) { // In two-pane mode, show the detail view in this activity by // adding or replacing the detail fragment using a // fragment transaction. Bundle arguments = new Bundle(); arguments.putString(ItemDetailFragment.ARG_ITEM_ID, id); ItemDetailFragment fragment = new ItemDetailFragment(); fragment.setArguments(arguments); getSupportFragmentManager().beginTransaction() .replace(R.id.item_detail_container, fragment).commit(); } else { // In single-pane mode, simply start the detail activity // for the selected item ID. Intent detailIntent = new Intent(this, ItemDetailActivity.class); detailIntent.putExtra(ItemDetailFragment.ARG_ITEM_ID, id); startActivity(detailIntent); } } 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; } }
我怎样才能更有效地做到这一点？现在，当我启动其中一个 Activity 时，它会循环初始化位。它一直在循环中创建相同的活动，直到我按下菜单按钮。