我的应用程序有 5 个不同的活动（将它们命名为 A、B、C、D、E）并且有一个菜单（由屏幕底部的按钮组成），用于在 A、B...E 之间切换/p>
当我显示 A 时，有一些按钮，用户可以通过它在 A 之上进行另一个活动 A1，然后从那里进入 A12，所以我的活动堆栈类似于 A>A1>A12，现在用户单击 B 的菜单按钮，然后他从那里继续 B1。 （堆栈就像 A>A1>A12>B>B1）现在如果用户按下按钮切换回 A，那么它应该显示 A12，因为它在 A 的顶部。
我该如何管理这个扫描仪？我一点提示都没有
【问题讨论】：
标签： android android-activity subactivity activity-stack
代替屏幕底部的按钮，使用 TabHost 和 ActivityGroup 在选定的选项卡下显示多个活动。
<TabHost
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@android:id/tabhost"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<LinearLayout
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<FrameLayout
android:id="@android:id/tabcontent"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="1" />
<TabWidget
android:id="@android:id/tabs"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="0" />
</LinearLayout>
</TabHost>
主要活动：
/**
* Activity that displays the main tabs and manages separate activity for the
* selected tab.
*/
public class MainActivity extends TabActivity {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// load main view
setContentView(R.layout.main_activity);
// get the TabHost
TabHost tabHost = getTabHost();
// resusable TabSpec for each tab
TabHost.TabSpec spec;
// reusable Intent for each tab
Intent intent;
// first tab
intent = new Intent(this, TabGroupActivity.class);
spec = tabHost.newTabSpec("first")
.setIndicator(createTabIndicatorView(tabHost, "First", R.drawable.ic_tab_first))
.setContent(intent);
tabHost.addTab(spec);
// second tab
intent = new Intent(this, TabGroupActivity.class);
spec = tabHost.newTabSpec("second")
.setIndicator(createTabIndicatorView(tabHost, "Second", R.drawable.ic_tab_second))
.setContent(intent);
tabHost.addTab(spec);
tabHost.setCurrentTab(0);
}
/**
* Creates tabs with custom layout.
*
* @param tabHost the tab host
* @param tabTitle the title of the tab
* @param icon the icon of the tab
* @return the view representing single tab
*/
private View createTabIndicatorView(TabHost tabHost, CharSequence tabTitle, int icon) {
LayoutInflater inflater = (LayoutInflater) this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View tabIndicator = inflater.inflate(R.layout.tab_indicator, tabHost, false);
final TextView tv = (TextView) tabIndicator.findViewById(R.id.title);
tv.setText(tabTitle);
final ImageView iconView = (ImageView) tabIndicator.findViewById(R.id.icon);
iconView.setImageDrawable(getResources().getDrawable(icon));
return tabIndicator;
}
}
活动组：
/**
* The purpose of this Activity is to manage the activities in a tab. Note:
* Child Activities can handle Key Presses before they are seen here.
*/
public class TabGroupActivity extends ActivityGroup {
private ArrayList<String> mIdList;
public TabGroupActivity() {
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (mIdList == null) {
mIdList = new ArrayList<String>();
}
startChildActivity("firstChildActivity", new Intent(this, FirstChildActivity.class));
}
/**
* This is called when a child activity of this one calls its finish method.
* This implementation calls {@link LocalActivityManager#destroyActivity} on
* the child activity and starts the previous activity. If the last child
* activity just called finish(),this activity (the parent), calls finish to
* finish the entire group.
*/
@Override
public void finishFromChild(Activity child) {
LocalActivityManager manager = getLocalActivityManager();
int index = mIdList.size() - 1;
if (index < 1) {
finish();
return;
}
manager.destroyActivity(mIdList.get(index), true);
mIdList.remove(index);
index--;
String lastId = mIdList.get(index);
Intent lastIntent = manager.getActivity(lastId).getIntent();
Window newWindow = manager.startActivity(lastId, lastIntent);
setContentView(newWindow.getDecorView());
}
/**
* Starts an Activity as a child Activity to this.
*
* @param Id Unique identifier of the activity to be started.
* @param intent The Intent describing the activity to be started.
* @throws android.content.ActivityNotFoundException.
*/
public void startChildActivity(String Id, Intent intent) {
Window window = getLocalActivityManager().startActivity(Id,
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP));
if (window != null) {
mIdList.add(Id);
setContentView(window.getDecorView());
}
}
/**
* The primary purpose is to prevent systems before
* android.os.Build.VERSION_CODES.ECLAIR from calling their default
* KeyEvent.KEYCODE_BACK during onKeyDown.
*/
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
// preventing default implementation previous to
// android.os.Build.VERSION_CODES.ECLAIR
return true;
}
return super.onKeyDown(keyCode, event);
}
/**
* Overrides the default implementation for KeyEvent.KEYCODE_BACK so that all
* systems call onBackPressed().
*/
@Override
public boolean onKeyUp(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
onBackPressed();
return true;
}
return super.onKeyUp(keyCode, event);
}
/**
* If a Child Activity handles KeyEvent.KEYCODE_BACK. Simply override and add
* this method.
*/
@Override
public void onBackPressed() {
int length = mIdList.size();
if (length > 1) {
Activity current = getLocalActivityManager().getActivity(mIdList.get(length - 1));
current.finish();
} else {
super.onBackPressed();
}
}
}
【讨论】：
我建议你应该创建一个包含所有 5 个 Activity A、B、C、D、E 的 tabHost。
初始化tabHost后，通过调用隐藏这个标签栏：
tabHost.getTabWidget.setVisibility(View.GONE);
你应该像这样在每个 Activity 之间切换：
public boolean onOptionsItemSelected( MenuItem item )
{
switch (item.getItemId())
{
case R.id.menu_item_A:
tabHost.setCurrentTab(0);
return true;
case R.id.menu_item_B:
tabHost.setCurrentTab(1);
return true;
case R.id.menu_item_C:
tabHost.setCurrentTab(2);
return true;
case R.id.menu_item_D:
tabHost.setCurrentTab(3);
return true;
case R.id.menu_item_E:
tabHost.setCurrentTab(4);
return true;
return false;
}
所以，当你在 A1 -> A2，并切换到 Activity B，并使用菜单切换回 A，你仍然在 A2。
希望对你有帮助。
【讨论】：