我正在尝试使用BottomNavigationView创建应用。我添加了三个片段，它只能工作一次，但是当我尝试从botton视图中重新选择一个项目应用程序崩溃。这是我的mainActivity.java代码
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.BottomNavigationView;
import android.support.v7.app.AppCompatActivity;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity implements BottomNavigationView.OnNavigationItemSelectedListener {
private TextView mTextMessage;
FragmentManager fragmentManager;
FragmentTransaction fragmentTransaction;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(this);
fragmentManager = getFragmentManager();
fragmentTransaction = fragmentManager.beginTransaction();
//fragmentTransaction.add(R.id.fragment, homeFragment).commit();
}
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.navigation_home:
fragmentTransaction.replace(R.id.fragment, new HomeFragment()).commit();
return true;
case R.id.navigation_dashboard:
fragmentTransaction.replace(R.id.fragment, new Dashboardfragment()).commit();
return true;
case R.id.navigation_notifications:
fragmentTransaction.replace(R.id.fragment, new NotificationFragment()).commit();
return true;
}
return false;
}
}
和我的一个片段.java代码如下所示。在我遇到一个不同的问题，我无法替换我的片段意味着我的家庭片段仍然存在，即使我试图改变。
public class HomeFragment extends Fragment {
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
if (container != null) {
container.removeAllViews();
}
View view = inflater.inflate(R.layout.fragment_home,container,false);
return view;
}
}
ok这是我的日志文件：
10-07 02:38:05.768 22895-22964/com.example.anonymous.bottomnavigationbar I/Adreno-EGL: <qeglDrvAPI_eglInitialize:379>: EGL 1.4 QUALCOMM build: AU_LINUX_ANDROID_LA.BR.1.1.3.C8.05.01.00.115.128_msm8916_64_refs/tags/AU_LINUX_ANDROID_LA.BR.1.1.3.C8.05.01.00.115.128__release_AU (I55c48cad9a)
OpenGL ES Shader Compiler Version: E031.25.03.04
Build Date: 03/21/17 Tue
Local Branch:
Remote Branch: refs/tags/AU_LINUX_ANDROID_LA.BR.1.1.3.C8.05.01.00.115.128
Local Patches: NONE
Reconstruct Branch: NOTHING
10-07 02:38:05.788 22895-22964/com.example.anonymous.bottomnavigationbar I/OpenGLRenderer: Initialized EGL, version 1.4
10-07 02:38:05.848 22895-22964/com.example.anonymous.bottomnavigationbar D/OpenGLRenderer: Enabling debug mode 0
10-07 02:38:05.928 22895-22895/com.example.anonymous.bottomnavigationbar W/art: Before Android 4.1, method int android.support.v7.widget.ListViewCompat.lookForSelectablePosition(int, boolean) would have incorrectly overridden the package-private method in android.widget.ListView
10-07 02:38:12.918 22895-22895/com.example.anonymous.bottomnavigationbar D/AndroidRuntime: Shutting down VM
10-07 02:38:12.918 22895-22895/com.example.anonymous.bottomnavigationbar E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.anonymous.bottomnavigationbar, PID: 22895
java.lang.IllegalStateException: commit already called
at android.app.BackStackRecord.commitInternal(BackStackRecord.java:714)
at android.app.BackStackRecord.commit(BackStackRecord.java:705)
at com.example.anonymous.bottomnavigationbar.MainActivity.onNavigationItemSelected(MainActivity.java:44)
at android.support.design.widget.BottomNavigationView$1.onMenuItemSelected(BottomNavigationView.java:184)
at android.support.v7.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:821)
at android.support.v7.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:158)
at android.support.v7.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:968)
at android.support.design.internal.BottomNavigationMenuView$1.onClick(BottomNavigationMenuView.java:95)
at android.view.View.performClick(View.java:4781)
at android.view.View$PerformClick.run(View.java:19907)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:160)
at android.app.ActivityThread.main(ActivityThread.java:5541)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:964)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:759)
10-07 02:38:12.968 22895-22895/com.example.anonymous.bottomnavigationbar I/Process: Sending signal. PID: 22895 SIG: 9
10-07 02:38:12.968 22895-22895/com.example.anonymous.bottomnavigationbar V/Process: killProcess [22895] Callers=com.android.internal.os.RuntimeInit$UncaughtHandler.uncaughtException:99 java.lang.ThreadGroup.uncaughtException:693 java.lang.ThreadGroup.uncaughtException:690 <bottom of call stack>
答案 0 :(得分：1)
好了，现在我只是通过创建一个方法并在那里创建和初始化FragmentManager和FragmentTrasaction来解决这个错误，它对我来说很有用。可能是错误是由于我们只能为一次多次提交提交FragmentTransaction，我们需要一次又一次地声明它。这是我的方法：
private void openFragment(final Fragment fragment) {
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.replace(R.id.fragment, fragment);
transaction.addToBackStack(null);
transaction.commit();
}
答案 1 :(得分：0)
每次点击都需要一个全新的交易，但您只需在onCreate()开始一次，并多次尝试commit()。您可以按如下方式更新代码以解决问题：
// Remove following two lines...
// FragmentManager fragmentManager;
// FragmentTransaction fragmentTransaction;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(this);
}
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
switch (item.getItemId()) {
case R.id.navigation_home:
fragmentTransaction.replace(R.id.fragment, new HomeFragment()).commit();
return true;
case R.id.navigation_dashboard:
fragmentTransaction.replace(R.id.fragment, new Dashboardfragment()).commit();
return true;
case R.id.navigation_notifications:
fragmentTransaction.replace(R.id.fragment, new NotificationFragment()).commit();
return true;
}
return false;
}