我正在使用一个带有底部导航视图的简单应用程序。 我有3个带文本的片段,我想在Botton Navigation中选择一个项目时启动它们,但我不知道在MainActivity.java中要写什么; 所有片段都有.xml布局和.java。 我搜索了一些代码,我写了它们,我搜索视频,但我没有成功。
我正在学习Fragments和UI Dynamic,所以我在Android Studio中使用Bottom Navigation Activity创建了一个新项目。 所以,在我的activity_main中,我在Bottom Navigation中有3个itens,在Bottom Navigation上面有一个framelayout,占用了所有父级。这个想法是:当我在底部导航中选择一个项目时,它将在framelayout中显示另一个布局。所以我在布局文件夹中创建了3个xml布局(也使用了java类),在framelayout中创建了一个片段。现在,当我选择一个项目时,我正试图在我的framelayout(有一个片段)中显示这些布局。但我不知道该怎么做。
主要活动
private TextView mTextMessage;
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
= new BottomNavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
Fragment selectedFragment = null;
switch (item.getItemId()) {
case R.id.navigation_home:
selectedFragment = HomeFragment.newInstance();
break;
case R.id.navigation_dashboard:
selectedFragment = DashboardFragment.newInstance();
break;
case R.id.navigation_notifications:
selectedFragment = NotificationsFragment.newInstance();
break;
}
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.content, selectedFragment);
transaction.commit();
return true;
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.content, HomeFragment.newInstance());
transaction.commit();
}
activity_main xml
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="bandeira.thalisson.barradenavegacaoembaixo.MainActivity">
<FrameLayout
android:id="@+id/content"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1">
</FrameLayout>
<android.support.design.widget.BottomNavigationView
android:id="@+id/navigation"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom"
android:background="?android:attr/windowBackground"
app:menu="@menu/navigation"/>
导航xml
<item
android:id="@+id/Fragment_one"
android:icon="@drawable/ic_home_black_24dp"
android:title="@string/title_home"/>
<item
android:id="@+id/Fragment_two"
android:icon="@drawable/ic_dashboard_black_24dp"
android:title="@string/title_dashboard"/>
<item
android:id="@+id/Fragment_three"
android:icon="@drawable/ic_notifications_black_24dp"
android:title="@string/title_notifications"/>
Fragment.java示例
public class HomeFragment extends Fragment {
public static HomeFragment newInstance() {
HomeFragment fragment = new HomeFragment();
return fragment;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.navigation_home, container, false);
return inflater.inflate(R.layout.navigation_home, container, false);
}
答案 0 :(得分:3)
首先,在您的activity_main.xml中,我们不需要3个不同的片段,因为我们可以在1个FrameLayout中替换或添加我们任何选定的片段。 其次,当用户从Bottom NavigationView中选择任何一个时,只需获取相关Fragment类的实例,并将其替换为您的activity_main的FrameLayout。
Fragment selectedFragment = null;
switch (item.getItemId()) {
case R.id.navigation_home:
selectedFragment = FunFragment.newInstance();
break;
获取所选片段的实例后,将其替换为activity_main的FrameLayout,以便在屏幕上显示。
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.content, selectedFragment);
transaction.commit();
编辑标签 第1步。您的activity_main.xml应该如下所示
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="com.exampl.MainActivity">
<FrameLayout
android:id="@+id/content"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"/>
<android.support.design.widget.BottomNavigationView
android:id="@+id/navigation"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom"
android:background="?android:attr/windowBackground"
app:menu="@menu/navigation" />
</LinearLayout>
第2步。您的fragment_home.xml布局应该是这样的
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="android"/>
</LinearLayout>
为您的三个不同选项制作3种不同的片段布局
第3步。您的MainActivity.java类将是这样的
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
= new BottomNavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(MenuItem item) {
Fragment selectedFragment = null;
switch (item.getItemId()) {
case R.id.navigation_home:
selectedFragment = FunFragment.newInstance();
break;
case R.id.navigation_dashboard:
selectedFragment = TheoryFragment.newInstance();
break;
case R.id.navigation_notifications:
selectedFragment = AndroidFragment.newInstance();
break;
}
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.content, selectedFragment);
transaction.commit();
return true;
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ButterKnife.bind(this);
navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.content, FunFragment.newInstance());
transaction.commit();
}
在创建替换时,您要在启动应用程序后显示要显示的片段,导航侦听器将处理您将选择的选项
第4步。您将拥有3个不同的Fragment类,看起来像这样
public class TheoryFragment extends Fragment {
public static TheoryFragment newInstance() {
TheoryFragment fragment = new TheoryFragment();
return fragment;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_theory, container, false);
unbinder = ButterKnife.bind(this, rootView);
return rootView;
}
}
希望它能帮助你,让我知道是否有任何问题。
答案 1 :(得分:3)
获取HomeFragment,DashboardFragment和NotificationFragment等三个片段以及这三个片段的三个布局。
<强> HomeFragment 强>
public class HomeFragment extends Fragment {
public HomeFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_home, container, false);
}
}
<强> fragment_home.xml 强>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Home Fragment"
android:textStyle="bold"
android:layout_gravity="center"/>
</FrameLayout>
** DashboardFragment **
public class DashboardFragment extends Fragment {
public DashboardFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_dashboard, container, false);
}
}
<强> fragment_dashboard.xml 强>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Dashboard Fragment"
android:textStyle="bold"
android:layout_gravity="center"/>
</FrameLayout>
** NotificationFragment **
public class NotificationFragment extends Fragment {
public NotificationFragment () {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_notification, container, false);
}
}
<强> fragment_notification.xml 强>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Notification Fragment"
android:textStyle="bold"
android:layout_gravity="center"/>
</FrameLayout>
这是你的活动。
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
int id = item.getItemId();
switch (id){
case R.id.Fragment_one:
fragment = new HomeFragment();
break;
case R.id.Fragment_two:
fragment = new DashboardFragment();
break;
case R.id.Fragment_three:
fragment = new NotificationFragment();
break;
}
final FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.replace(R.id.main_container, fragment).commit();
return true;
}
});
答案 2 :(得分:1)
我想补充一点,如果您想使用BottomNavigationView.OnNavigationItemSelectedListener()
选择开始片段,可以使用setSelectedItemId()
,例如:
替换&#39; R.id.navigation_home &#39;用你自己的开始片段。
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
BottomNavigationView navigation = (BottomNavigationView)
findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
navigation.setSelectedItemId(R.id.navigation_home);
}
答案 3 :(得分:1)
单独创建此方法
protected boolean openFragment(Fragment fragment){
getSupportFragmentManager()
.beginTransaction()
.replace(R.id.content, fragment)
.commit();
return true;
}
要在开关中进行编辑
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.navigation_home: return openFragment(OneFragment.newInstance("",""));
case R.id.navigation_beehive: return openFragment(twoFragment.newInstance("",""));
case R.id.navigation_notifications: return openFragment(otherFragment.newInstance("",""));
}
return false;
}
要进行最终确定,您可以使用中的片段进行初始化
protected void onCreate(Bundle savedInstanceState) {
....
openFragment(OneFragment.newInstance("",""));
}