我已经实现了BottomNavigationView并且不知道如何设置选择索引或MenuItem
id(在我的情况下,默认情况下应选择中间项)。
我担心现在没有这种可能性,因为它太原始了,但无论如何任何帮助都将受到赞赏。谢谢!
使用setSelectedItemId
设置所选菜单项ID:
bottomNavigationView.setSelectedItemId(R.id.item_id);
此方法已从Android支持库25.3.0开始提供。
实现BottomNavigationView.OnNavigationItemSelectedListener
并在初始化时设置selectedItemId
。
this.bottomNavigationView.setOnNavigationItemSelectedListener {
val targetFragment = when (menuItem.itemId) {
R.id.action_home -> {
HomeFragment()
}
R.id.action_post -> {
PostFragment()
}
R.id.action_settings -> {
SettingsFragment()
}
else -> null
}
targetFragment?.let {
this.activity?.supportFragmentManager?.transaction {
replace(R.id.containerLayout, it, it.javaClass.simpleName)
}
}
true
}
this.bottomNavigationView.selectedItemId = R.id.action_home
对我有用的唯一解决方案是:
View view = bottomNavigationView.findViewById(R.id.menu_action_dashboard);
view.performClick();
只需执行点击即可。希望我们在将来的版本中有额外的方法/属性。
UPD:
作为user5968678 mentioned,自Android支持库v25.3.0以来添加了新方法:
bottomNavigationView.setSelectedItemId(R.id.item_id);
所以请改用:)
我认为这个解决方案比接受的答案稍微优雅一点:
bottomNavigationView.getMenu().getItem(menuItemIndex).setChecked(true)
其中menuItemIndex是所选元素的索引。
这是the documentation所说的:
菜单项也可用于以编程方式选择当前活动的目的地。它可以使用
MenuItem#setChecked(true)
完成
作为Jan发布的替代方案,您还可以按ID找到该项目:
Menu menu = findViewById(R.id.navigation).getMenu();
menu.findItem(R.id.navigation_home).setChecked(true);
另外,我建议打电话给.callOnClick()
instead of .performClick()
。
如果你正在使用监听器,比如android studio中的默认实现,试试这个:
BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
Integer indexItem = 4;
navigation.getMenu().getItem(indexItem).setChecked(true);
mOnNavigationItemSelectedListener.onNavigationItemSelected(navigation.getMenu().getItem(indexItem));
我相信在这个背景下的问题是基于这里的答案在不同的背景下看待。根据评估,所需要的是能够专注于特定的BottomNavigationView
项目(绝对是在新类别持有不同的片段)。
现在,您可以使用BottomNavigationView OR Buttons或Anything clickable来启动意图的新活动: - 即
Intent intent = new Intent(getActivity(), New_Activity.class);
intent.putExtra("EXTRA_PAGE, 1);
startActivityForResult(intent, 30);
然后 - 在我们的New_Activity中,我们收到了意图 -
Intent intent = getIntent(); int page = intent.getExtras()。getInt(“EXTRA_PAGE);
然后我们遍历页面变量以找到当前BottomNavigationView反映的数字/索引,然后我们设置焦点菜单项(假设你的BottomNavigationView有显示的菜单项)
if(page == 1) {
currentselect = new Pending();
bottomNavigationView.getMenu().getItem(0).setChecked(true);
}
这回答了上面的问题。 Fragment开关的其余部分通过调用以上帖子的数量很好地处理:
bottomNavigationView.setOnNavigationItemSelectedListener(navListener);
private BottomNavigationView.OnNavigationItemSelectedListener navListener =
new BottomNavigationView.OnNavigationItemSelectedListener(){
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
Fragment selectedFrag = null;
switch (item.getItemId()) {
case R.id.pending:
selectedFrag = new Pending();
break;
case R.id.onTransmit:
selectedFrag = new inTransmit();
break;
case R.id.complete:
selectedFrag = new Complete();
break;
}
getSupportFragmentManager().beginTransaction().replace(R.id.select_field, selectedFrag).commit();
return true;
}
};
注意:使用BottomNavigationView和ContentFrameLayout非常经济,并且与使用ViewPager和Tablayout相似,将代码缩减到50%以上
停止使用Reflection!这是坏的!
好吧,虽然支持库没有让我们选择BottomNavigationView中的项目,以便在第一次显示时显示,我们有两种可能:
首先,使用循环:
private void setupBottomNavigationView() {
// Get the menu from our navigationBottomView.
Menu bottomNavigationViewMenu = bottomNavigationView.getMenu();
// Uncheck the first menu item (the default item which is always checked by the support library is at position 0).
bottomNavigationMenu.findItem(R.id.action_one).setChecked(false);
// Check the wished first menu item to be shown to the user.
bottomNavigationMenu.findItem(R.id.action_two).setChecked(true);
bottomNavigationView.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
Menu bottomNavigationMenu = bottomNavigationView.getMenu();
for (int i = 0; i < bottomNavigationMenu.size(); i++) {
if (item.getItemId() != bottomNavigationMenu.getItem(i).getItemId()) {
bottomNavigationMenu.getItem(i).setChecked(false);
}
}
switch (item.getItemId()) {
case R.id.action_one :
replaceFragment(new OneFragment());
break;
case R.id.action_two :
replaceFragment(new TwoFragment());
break;
case R.id.action_three :
replaceFragment(new ThreeFragment());
break;
}
return false;
}
});
}
第二,没有循环但有一个类变量(因为逻辑是从内部类中完成的):
private void setupBottomNavigationView() {
// Get the menu from our navigationBottomView.
Menu bottomNavigationViewMenu = bottomNavigationView.getMenu();
// Uncheck the first menu item (the default item which is always checked by the support library is at position 0).
bottomNavigationViewMenu.findItem(R.id.action_one).setChecked(false);
// Check the wished first menu item to be shown to the user. Also store that menu item on a variable to control when a menu item must be unchecked.
mActiveBottomNavigationViewMenuItem = bottomNavigationViewMenu.findItem(R.id.action_two).setChecked(true);
bottomNavigationView.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem selectedMenuItem) {
switch (selectedMenuItem.getItemId()) {
case R.id.action_one :
replaceFragment(new OneFragment());
break;
case R.id.action_two :
replaceFragment(new TwoFragment());
break;
case R.id.action_three :
replaceFragment(new ThreeFragment());
break;
}
if (selectedMenuItem != mActiveBottomNavigationViewMenuItem){
mActiveBottomNavigationViewMenuItem.setChecked(false);
mActiveBottomNavigationViewMenuItem = selectedMenuItem;
}
return false;
}
});
}
private MenuItem mActiveBottomNavigationViewMenuItem;
当执行setupBottomNavigationView()方法时?在Activity onCreate()方法中,看一下:
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// ...
setupBottomNavigationView();
}
简单,没有广泛的代码。
希望能帮助到你!
底部导航中初始选定项目的Kotlin代码.BottomNavigationView:
bottom_navigation_view.selectedItemId = R.id.navigation_item_messages
您可以扩展BottomNavigationView并使用反射来调用私有方法。
public class SelectableBottomNavigationView extends BottomNavigationView {
public SelectableBottomNavigationView(Context context) {
super(context);
}
public SelectableBottomNavigationView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public SelectableBottomNavigationView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
public void setSelected(int index) {
try {
BottomNavigationMenuView menuView = (BottomNavigationMenuView) getField(BottomNavigationView.class, "mMenuView");
OnNavigationItemSelectedListener listener = (OnNavigationItemSelectedListener) getField(BottomNavigationView.class, "mListener");
try {
Method method = menuView.getClass().getDeclaredMethod("activateNewButton", Integer.TYPE);
method.setAccessible(true);
// activate item.
method.invoke(menuView, index);
if (listener != null) {
// trigger item select event.
listener.onNavigationItemSelected(getMenu().getItem(index));
}
} catch (SecurityException | NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
e.printStackTrace();
}
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (NoSuchFieldException e) {
e.printStackTrace();
}
}
private Object getField(Class clazz, String fieldName) throws NoSuchFieldException, IllegalAccessException {
Field f = clazz.getDeclaredField(fieldName);
f.setAccessible(true);
return f.get(this);
}
}