我正在尝试使一个活动由4个片段组成。 滑动（而不破坏）后，每个片段都会被另一个片段替换。
当我向左滑动两次达到第三个片段时，应用程序将终止并显示错误代码
java.lang.IllegalStateException：片段已添加：[第四个片段] {8e8204d＃3 id = 0x7f080033 android：switcher：2131230771：3}
但是问题是，在包含片段的活动首次调用onCreate之后，我没有添加任何片段。
任何人都可以给我一个建议，直接解决该问题吗？
我主要活动的代码如下。
import android.location.Location;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.EditText;
import java.util.ArrayList;
import java.util.List;
public class AnalysisActivity extends AppCompatActivity implements LocationFragment.OnFragmentInteractionListener, TypeFragment.OnFragmentInteractionListener, CountFragment.OnFragmentInteractionListener, SummaryFragment.OnFragmentInteractionListener {
/**
* The {@link android.support.v4.view.PagerAdapter} that will provide
* fragments for each of the sections. We use a
* {@link FragmentPagerAdapter} derivative, which will keep every
* loaded fragment in memory. If this becomes too memory intensive, it
* may be best to switch to a
* {@link android.support.v4.app.FragmentStatePagerAdapter}.
*/
private SectionsPagerAdapter mSectionsPagerAdapter;
/**
* The {@link ViewPager} that will host the section contents.
*/
private ViewPager mViewPager;
private LocationFragment locationFragment;
private TypeFragment typeFragment;
private CountFragment countFragment;
private SummaryFragment summaryFragment;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_analysis);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Create the adapter that will return a fragment for each of the three
// primary sections of the activity.
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
locationFragment = new LocationFragment();
typeFragment = new TypeFragment();
countFragment = new CountFragment();
summaryFragment = new SummaryFragment();
mSectionsPagerAdapter.addFragment(locationFragment, "LocationFragment");
mSectionsPagerAdapter.addFragment(summaryFragment, "SummaryFragment");
mSectionsPagerAdapter.addFragment(typeFragment, "TypeFragment");
mSectionsPagerAdapter.addFragment(countFragment, "CountFragment");
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.container);
mViewPager.setAdapter(mSectionsPagerAdapter);
getSupportFragmentManager().beginTransaction()
.replace(R.id.container, locationFragment)
.replace(R.id.container, summaryFragment)
.replace(R.id.container, typeFragment)
.replace(R.id.container, countFragment)
.commit();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_analysis, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
public PlaceholderFragment() {
}
/**
* Returns a new instance of this fragment for the given section
* number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = null;
switch (getArguments().getInt(ARG_SECTION_NUMBER)) {
case 1:
rootView = inflater.inflate(R.layout.fragment_location, container, false);
break;
case 2:
rootView = inflater.inflate(R.layout.fragment_type, container, false);
break;
case 3:
rootView = inflater.inflate(R.layout.fragment_count, container, false);
break;
case 4:
rootView = inflater.inflate(R.layout.fragment_summary, container, false);
break;
}
return rootView;
}
}
@Override
public void onInputLocationSent(CharSequence input) {
summaryFragment.updateEditText_summary_location(input);
}
@Override
public void onInputTypeSent(CharSequence input) {
summaryFragment.updateEditText_summary_type(input);
}
@Override
public void onInputCountSent(CharSequence input) {
summaryFragment.updateEditText_summary_count(input);
}
@Override
public void onInputSummaryLocationSent(CharSequence input) {
}
@Override
public void onInputSummaryTypeSent(CharSequence input) {
}
@Override
public void onInputSummaryCountSent(CharSequence input) {
}
/**
* A {@link FragmentPagerAdapter} that returns a fragment corresponding to
* one of the sections/tabs/pages.
*/
public class SectionsPagerAdapter extends FragmentPagerAdapter {
private final List<Fragment> mFragmentList = new ArrayList<>();
private final List<String> mFragmentTitleList = new ArrayList<>();
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
public void addFragment(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
@Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a PlaceholderFragment (defined as a static inner class below).
// return PlaceholderFragment.newInstance(position + 1);
return mFragmentList.get(position);
}
@Override
public int getCount() {
return mFragmentList.size();
}
}
}
答案 0 :(得分：1)
删除以下代码。我不确定目的是什么，但这可能是您问题的根源。
getSupportFragmentManager().beginTransaction()
.replace(R.id.container, locationFragment)
.replace(R.id.container, summaryFragment)
.replace(R.id.container, typeFragment)
.replace(R.id.container, countFragment)
.commit();
以上代码的结果是将R.id.container替换为 locationFragment ，然后依次是 summaryFragment 和 typeFragment ，最后是 countFragment （R.id.container最后将实际包含在内）。结果，当您滑动时，第三次滑动是 countFragment ，它是上述代码添加的，因此是重复的。
FragmentPagerAdapter 将为您处理片段。您不需要自己添加它们。