我需要从Single Class扩展两个类。我的类要扩展ListActivity和amp; MainActivity。
我发现了类似的问题。 但我不知道如何实施这个https://stackoverflow.com/a/5836735/2781359
感谢您的帮助。
必须扩展的类是ConnectionEditActivity。
public class ConnectionEditActivity extends ListActivity implements OnClickListener
{
public static Connection connectionParam;
private Connection connection;
private Button save;
private EditText name;
private EditText password;
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
this.connection = connectionParam;
this.save = (Button) this.findViewById(R.id.save);
this.save.setOnClickListener(this);
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.GINGERBREAD)
{
// Don't need the Save button on newer devices
android.widget.LinearLayout.LayoutParams a = (LayoutParams) this.save.getLayoutParams();
a.height = 0;
this.save.setLayoutParams(a);
this.save.forceLayout();
}
this.name = (EditText) this.findViewById(R.id.name);
this.password = (EditText) this.findViewById(R.id.password);
}
@Override
public boolean onCreateOptionsMenu(android.view.Menu menu)
{
// Inflate the menu items for use in the action bar
android.view.MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.connection_edit_menu, menu);
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(android.view.MenuItem item)
{
// Handle presses on the action bar items
switch (item.getItemId())
{
case R.id.action_save:
this.finish();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
protected void onResume()
{
super.onResume();
this.name.setText(this.connection.getName());
this.password.setText(this.connection.getPassword());
}
protected void onPause()
{
super.onPause();
this.connection.setName(this.name.getText().toString());
this.connection.setPassword(this.password.getText().toString());
finish();
}
public void onClick(View v)
{
if (v == this.save)
{
this.finish();
}
}
}
Mainactivity
public abstract class MainActivity extends ActionBarActivity
{
protected ListView mDrawerList;
protected DrawerLayout mDrawer;
private CustomActionBarDrawerToggle mDrawerToggle;
private String[] menuItems;
String LOG_TAG = "Remote It";
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
supportRequestWindowFeature(WindowCompat.FEATURE_ACTION_BAR);
// getSupportActionBar().hide();
setContentView(R.layout.activity_main_drawer);
// enable ActionBar app icon to behave as action to toggle nav drawer
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeButtonEnabled(true);
mDrawer = (DrawerLayout) findViewById(R.id.drawer_layout);
// set a custom shadow that overlays the main content when the drawer
// opens
mDrawer.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);
_initMenu();
mDrawerToggle = new CustomActionBarDrawerToggle(this, mDrawer);
mDrawer.setDrawerListener(mDrawerToggle);
}
private void _initMenu()
{
NsMenuAdapter mAdapter = new NsMenuAdapter(this);
// Add Header
mAdapter.addHeader(R.string.ns_menu_main_header);
// Add first block
menuItems = getResources().getStringArray(R.array.ns_menu_items);
String[] menuItemsIcon = getResources().getStringArray(R.array.ns_menu_items_icon);
int res = 0;
for (String item : menuItems)
{
int id_title = getResources().getIdentifier(item, "string", this.getPackageName());
int id_icon = getResources().getIdentifier(menuItemsIcon[res], "drawable", this.getPackageName());
NsMenuItemModel mItem = new NsMenuItemModel(id_title, id_icon);
// if (res==1) mItem.counter=12; //it is just an example...
// if (res==3) mItem.counter=3; //it is just an example...
mAdapter.addItem(mItem);
res++;
}
// Second Block
mAdapter.addHeader(R.string.ns_menu_main_header2);
menuItems = getResources().getStringArray(R.array.ns_menu_itemss);
String[] menuItemsIcons = getResources().getStringArray(R.array.ns_menu_items_iconss);
int ress = 0;
for (String item : menuItems)
{
int id_title = getResources().getIdentifier(item, "string", this.getPackageName());
int id_icon = getResources().getIdentifier(menuItemsIcons[ress], "drawable", this.getPackageName());
NsMenuItemModel mItem = new NsMenuItemModel(id_title, id_icon);
// if (res==1) mItem.counter=12; //it is just an example...
// if (res==3) mItem.counter=3; //it is just an example...
mAdapter.addItem(mItem);
res++;
}
mDrawerList = (ListView) findViewById(R.id.drawer);
if (mDrawerList != null)
mDrawerList.setAdapter(mAdapter);
mDrawerList.setOnItemClickListener(new DrawerItemClickListener());
}
@Override
protected void onPostCreate(Bundle savedInstanceState)
{
super.onPostCreate(savedInstanceState);
// Sync the toggle state after onRestoreInstanceState has occurred.
mDrawerToggle.syncState();
}
@Override
public void onConfigurationChanged(Configuration newConfig)
{
super.onConfigurationChanged(newConfig);
mDrawerToggle.onConfigurationChanged(newConfig);
}
@Override
public boolean onOptionsItemSelected(MenuItem item)
{
/*
* The action bar home/up should open or close the drawer.
* ActionBarDrawerToggle will take care of this.
*/
if (mDrawerToggle.onOptionsItemSelected(item))
{
return true;
}
// Handle your other action bar items...
return super.onOptionsItemSelected(item);
}
private class CustomActionBarDrawerToggle extends ActionBarDrawerToggle
{
public CustomActionBarDrawerToggle(Activity mActivity, DrawerLayout mDrawerLayout)
{
super(mActivity, mDrawerLayout, R.drawable.ic_drawer, R.string.ns_menu_open, R.string.ns_menu_close);
}
@Override
public void onDrawerClosed(View view)
{
getSupportActionBar().setTitle(getString(R.string.ns_menu_close));
supportInvalidateOptionsMenu(); // creates call to
// onPrepareOptionsMenu()
}
@Override
public void onDrawerOpened(View drawerView)
{
getSupportActionBar().setTitle(getString(R.string.ns_menu_open));
supportInvalidateOptionsMenu(); // creates call to
// onPrepareOptionsMenu()
}
}
private class DrawerItemClickListener implements ListView.OnItemClickListener
{
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id)
{
mDrawer.closeDrawer(mDrawerList);
switch (position)
{
case 1:
Intent a = new Intent(MainActivity.this, Home.class);
startActivity(a);
break;
case 2:
Intent ac = new Intent(MainActivity.this, ConnectionListActivity.class);
startActivity(ac);
break;
default:
}
}
修改
我需要扩展它。因为MainActivity有导航抽屉。现在ConnectionEditActivity
没有显示navigationDrawer也没有显示ActionBar。但是我需要显示ActionBar
任何建议??
答案 0 :(得分：2)
在Java中，您无法扩展多个类，并且有充分的理由。以扩展MainActivity和ListActivity为例，您可以尝试实现的目标。在您的新班级中，当您致电：
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
...
}
你最重要的是onCreate（）？来自ListActivity的那个，或来自MainActivity的那个？
您发布的链接是说，您不是从另一个对象继承，而是组合您尝试使用的对象的新对象。例如：
public class NewClass extends OldClass1 {
private OldClass2 mOldClass2 = new OldClass2();
@Override
public methodFromOldClass1() {
}
public methodFromOldClass2() {
mOldClass2.methodFromOldClass2();
}
}
这种方法的问题在于MainActivity和ListActivity的方法仍然具有相同的名称，尽管你可以解决这个问题，但它很快就会变得很头疼。
因此问题是您设计类层次结构的结果。您需要从MainActivity考虑所需的功能，以及ListActivity中的哪些功能，并选择如何重新实现对象。
我的建议，因为ListActivity只使得使用列表稍微容易一点（不是那么容易），你可以跳过它并自己实现与列表相关的代码，这样你就可以延长MainActivity
答案 1 :(得分：1)
您需要首先确定需要继承的MainActivity部分，以及ListActivity需要什么。
然后，您有各种可能性：
ListActivity。扩展ListActivity仅为您提供了使用ListView的实用方法，但您可以在ListView中完全拥有Activity而不是ListActivity。 MainActivity中提取的方法，并从新类和MainActivity调用这些方法。MainActivity，使其扩展ListActivity。毕竟它确实包含ListView（你放弃了ActionBar的东西。）