我有一个ActionBar模式ActionBar.NAVIGATION_MODE_TABS,当我选择不同的标签时,我想更改ActionBar上显示的图标.
我使用Activity成功完成了它,但是当我再次在另一个Activity上应用它时,它表现得很奇怪.
假设我有两个标签:Tab1和Tab2,我想在选择Tab2时显示一个Camera图标,并在选择Tab1时消失.而且,Tab1是活动开始时将选择的第一个选项卡.
所以我做了这样的事情:
因为我不想在HomeActivity第一次启动时出现相机图标,所以我设置android:visible =“false”,然后当我在代码下面运行时:当HomeActivity启动时,相机图标不会出现在ActionBar上 – > ;正确,但是当我切换到tab2时,摄像头图标也没有出现在ActionBar上,但如果我按下“菜单”按钮 – > MenuItem是“Camera”,显示为溢出操作栏项.
如果我设置android:visible =“true” – >除了第一次HomeActivity开始时第一次出现相机图标(不正确!!!) – >当我更改tab1 / tab2时,相机图标会消失/正确显示.
这是我的代码:
actionbar_home.xml
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<item android:id="@+id/actionbar_home_camera"
android:title="@string/actionbar_rc_camera"
android:icon="@drawable/ic_action_camera"
android:showAsAction="always"
android:visible="false"/>
</menu>
HomeActivity.java
public class HomeActivity extends SherlockFragmentActivity {
private ActionBar actionBar;
private Menu menu;
private Tab1Fragment tab1Fragment;
private Tab2Fragment tab2Fragment;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
this.configActionBar();
this.createTabs();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getSupportMenuInflater().inflate(R.menu.actionbar_home, menu);
this.menu = menu;
// pass objects to tabs
tab1Fragment.setoptionMenu(this.menu);
tab2Fragment.setoptionMenu(this.menu);
return true;
}
@Override
public boolean onoptionsItemSelected(MenuItem item) {
return super.onoptionsItemSelected(item);
}
private void configActionBar()
{
actionBar = this.getSupportActionBar();
// below line makes application icon in top-left corner become a button
actionBar.setHomeButtonEnabled(true);
// below line add an arrow "<" before the top-left icon
//ab.setdisplayHomeAsUpEnabled(true);
//actionBar.setdisplayShowTitleEnabled(true);
}
private void createTabs()
{
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
ActionBar.Tab tab1 = actionBar.newTab().setText(
Const.TAB_TITLE_HOME_TAB1);
ActionBar.Tab tab2 = actionBar.newTab().setText(
Const.TAB_TITLE_HOME_TAB2);
// create the two fragments we want to use for display content
tab1Fragment = new Tab1Fragment();
tab2Fragment = new Tab2Fragment();
// add listener
tab1.setTabListener(
new HoMetabListener(tab1Fragment));
tab2.setTabListener(
new HoMetabListener(tab2Fragment));
actionBar.addTab(tab1);
actionBar.addTab(tab2);
}
}
BaseTabFragment.java
public class BaseTabFragment extends SherlockFragment{
protected View root;
protected Menu optionMenu;
protected SherlockFragmentActivity container;
public Menu getoptionMenu() {
return optionMenu;
}
public void setoptionMenu(Menu optionMenu) {
this.optionMenu = optionMenu;
}
public SherlockFragmentActivity getContainer() {
return container;
}
public void setContainer(SherlockFragmentActivity container) {
this.container = container;
}
}
Tab1Fragment.java
public class Tab1Fragment extends BaseTabFragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
root = inflater.inflate(R.layout.tab1_layout,
container, false);
this.changeActionBarLayout();
return root;
}
private void changeActionBarLayout()
{
try {
this.optionMenu.findItem(R.id.actionbar_home_camera)
.setVisible(false);
} catch (NullPointerException e)
{
// e will be thrown at the first time MainActivity is called
}
}
}
Tab2Fragment.java
public class Tab2Fragment extends BaseTabFragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
root = inflater.inflate(R.layout.tab2_layout,
container, false);
this.changeActionBarLayout();
return root;
}
private void changeActionBarLayout()
{
try {
this.optionMenu.findItem(R.id.actionbar_home_camera)
.setVisible(true);
// Camera Icon still doesn't appear on ActionBar even when I set it as SHOW_AS_ACTION_ALWAYS
this.optionMenu.findItem(R.id.actionbar_home_camera)
.setShowAsAction(MenuItem.SHOW_AS_ACTION_ALWAYS);
} catch (NullPointerException e)
{
// e will be thrown at the first time MainActivity is called
}
}
}
解决方法:
我遇到了同样的问题并找到了一个简单的解决方案:只需在Activity中实现onPreparePanel,即使所有项都不可见,也返回true.
public class HomeActivity extends SherlockFragmentActivity {
[...]
@Override
public boolean onPreparePanel(int featureId, View view, Menu menu) {
super.onPreparePanel(featureId, view, menu); // this returns false if all items are hidden
return true; // return true to prevent the menu's deletion
}
[...]
}