我有一个带有底部导航的应用程序，该应用程序在三个片段之间切换。当我单击菜单项时，我添加了过渡，并且我希望能够对其进行更多自定义，以便当我从左侧的项（ navigation_sync ）移至右侧的 navigation_message 或 navigation_settings ），过渡过程从右到左，反之亦然。我想将FrameLayout的内容与要通过switch更改为片段的内容进行比较，但是我对实际操作方法一无所知。
SelectActivity.java
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.BottomNavigationView;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.view.MenuItem;
import android.widget.FrameLayout;
public class SelectActivity extends AppCompatActivity {
private BottomNavigationView mMainNavigation;
private FrameLayout mMainFrame;
private SyncFragment syncFragment;
private MessageFragment messageFragment;
private SettingsFragment settingsFragment;
int toFragment;
@Override
public void onBackPressed() {
moveTaskToBack(true);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_select);
mMainFrame = (FrameLayout) findViewById(R.id.mainFrame);
mMainNavigation = (BottomNavigationView) findViewById(R.id.navigation);
syncFragment = new SyncFragment();
messageFragment = new MessageFragment();
settingsFragment = new SettingsFragment();
setFragment(syncFragment);
mMainNavigation.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
switch(item.getItemId()) {
case R.id.navigation_sync:
setFragment(syncFragment);
toFragment = R.id.navigation_sync;
return true;
case R.id.navigation_message:
setFragment(messageFragment);
toFragment = R.id.navigation_message;
return true;
case R.id.navigation_settings:
setFragment(settingsFragment);
toFragment = R.id.navigation_settings;
return true;
default:
return false;
}
}
});
}
private void setFragment(Fragment fragment) {
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
switch(R.id.mainFrame) {
case R.id.navigation_sync:
fragmentTransaction.setCustomAnimations(R.anim.enter_from_right, R.anim.exit_to_left);
case R.id.navigation_message:
if(toFragment == R.id.navigation_sync) {
fragmentTransaction.setCustomAnimations(R.anim.enter_from_left, R.anim.exit_to_right);
} else {
fragmentTransaction.setCustomAnimations(R.anim.enter_from_right, R.anim.exit_to_left);
}
case R.id.navigation_settings:
fragmentTransaction.setCustomAnimations(R.anim.enter_from_left, R.anim.exit_to_right);
}
//fragmentTransaction.setCustomAnimations(R.anim.enter_from_right, R.anim.exit_to_left);
fragmentTransaction.replace (R.id.mainFrame, fragment);
fragmentTransaction.commit();
}
}
这不读取任何 fragmentTransaction.setCustomAnimations ，所以我认为我在比较错误的值？请帮忙！
答案 0 :(得分：0)
我确实确实提出了解决问题的方法。
主要帮助者是Log.d(TAG, "Message");。有了这个，我就可以检查navigation_sync，syncFragment和我的toFragment变量的实际含义，然后就可以了。我发现syncFragment和其他对象拥有片段的ID，而我只需要将其与FrameLayout中当前的片段ID进行比较。可以使用以下方法完成：
public Fragment getFragmentId(){
return getSupportFragmentManager().findFragmentById(R.id.mainFrame);
}
所以我把它放到了我的交换机中：
...
switch(getFragmentId()) {
case syncFragment:
...
我收到一条错误消息：
我发现here的需要常量表达
可以通过将我所做的switch转换为if-else结构来解决。
这是所有可能遇到此问题的人的完整代码。请注意，我必须将toFragment变量更改为Fragment变量。同样，我在onNavigationItemSelected中在switch中设置语句的顺序也很重要。
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.BottomNavigationView;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.MenuItem;
import android.widget.FrameLayout;
public class SelectActivity extends AppCompatActivity {
private static final String TAG = "SelectActivity";
private BottomNavigationView mMainNavigation;
private FrameLayout mMainFrame;
private SyncFragment syncFragment;
private MessageFragment messageFragment;
private SettingsFragment settingsFragment;
private Fragment toFragment;
@Override
public void onBackPressed() {
moveTaskToBack(true);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_select);
mMainFrame = (FrameLayout) findViewById(R.id.mainFrame);
mMainNavigation = (BottomNavigationView) findViewById(R.id.navigation);
syncFragment = new SyncFragment();
messageFragment = new MessageFragment();
settingsFragment = new SettingsFragment();
setFragment(syncFragment);
toFragment = syncFragment;
mMainNavigation.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
switch(item.getItemId()) {
case R.id.navigation_sync:
toFragment = syncFragment;
setFragment(syncFragment);
return true;
case R.id.navigation_message:
setFragment(messageFragment);
return true;
case R.id.navigation_settings:
toFragment = settingsFragment;
setFragment(settingsFragment);
return true;
default:
return false;
}
}
});
}
private void setFragment(Fragment fragment) {
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
if (getFragmentId() == syncFragment) {
fragmentTransaction.setCustomAnimations(R.anim.enter_from_right, R.anim.exit_to_left);
}
if (getFragmentId()==messageFragment) {
if(toFragment == syncFragment) {
fragmentTransaction.setCustomAnimations(R.anim.enter_from_left, R.anim.exit_to_right);
} else {
fragmentTransaction.setCustomAnimations(R.anim.enter_from_right, R.anim.exit_to_left);
}
}
if (getFragmentId() == settingsFragment) {
fragmentTransaction.setCustomAnimations(R.anim.enter_from_left, R.anim.exit_to_right);
}
fragmentTransaction.replace (R.id.mainFrame, fragment);
fragmentTransaction.commit();
}
public Fragment getFragmentId(){
return getSupportFragmentManager().findFragmentById(R.id.mainFrame);
}
}