Question

我使用android studio

在这段代码上出错了

无法解析方法＆＃39; add（int，android.trey.startingpoint.nl.SecondActivity.PlaceHolderFragment）＆＃39;

    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_second);

    if (savedInstanceState == null) {
        getFragmentManager().beginTransaction()
                .add(R.id.container, new PlaceholderFragment()).commit();
    }
}

 public static class PlaceholderFragment extends Fragment {

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_second, container, false);
        return rootView;
    }
}

在单独的帖子中，我发现当你删除if部分时，事情应该很好，除了它会引发另一个错误。

感谢您的帮助！

编辑：进口：

import android.app.Activity;   import android.support.v4.app.Fragment;

导入android.os.Bundle; import android.view.LayoutInflater;进口   android.view.Menu; import android.view.MenuItem;进口   android.view.View; import android.view.ViewGroup;进口   android.widget.Toast;

导入com.google.android.gms.maps.CameraUpdateFactory;进口   com.google.android.gms.maps.GoogleMap;进口   com.google.android.gms.maps.MapFragment;进口   com.google.android.gms.maps.model.BitmapDescriptorFactory;进口   com.google.android.gms.maps.model.CameraPosition;进口   com.google.android.gms.maps.model.LatLng;进口   com.google.android.gms.maps.model.MarkerOptions;

Answer 1

PlaceholderFragment可能是支持片段。

将getFragmentManager更改为getSupportFragmentManager（），如下所示：

if (savedInstanceState == null) {
    getSupportFragmentManager().beginTransaction()
            .add(R.id.container, new PlaceholderFragment()).commit();
}

您的活动还必须扩展FragmentActivity。

注意：

如果您不打算使用支持片段，则只需更改片段的导入即可。

更改导入android.support.v4.app.Fragment;导入android.app.Fragment;

Answer 2

试试这个：

change getFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
to 
getSupportFragmentManager().beginTransaction()
.replace(R.id.container, new PlaceholderFragment()).commit();

Answer 3

将import android.app.Fragment;更改为android.support.v4.app.Fragment;

像

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.AppCompatActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;


public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment()).commit();
        }
    }

    public static class PlaceholderFragment extends Fragment {
        public PlaceholderFragment(){
        }

        @Override
        public View onCreateView(LayoutInflater inflater,ViewGroup container,Bundle savedInstanceState){
            View rootView = inflater.inflate(R.layout.fragment_main, container, false);
            return rootView;
        }
    }
}

Answer 4

在您的片段文件中使用import android.support.v4.app.Fragment;

而不是import android.app.Fragment;

比能解决它;

以下是示例：

在您的活动文件中：

 @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_set_travel_message);

    TravelMessageFragment fragment = new TravelMessageFragment();
    getSupportFragmentManager().beginTransaction().add(R.id.travelInit,fragment).commit();

}

比你的片段文件：

import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class TravelMessageFragment extends Fragment{
private View view;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup group, Bundle savedInstanceState) {
    view = inflater.inflate(R.layout.fragment_travel_message, group, false);

    return view;
}
}

Answer 5

无法解析方法'add（int，android.trey.startingpoint.nl.SecondActivity.PlaceHolderFragment）'

改变两件事

第一件事：

你可以创建类“android.trey.startingpoint.nl.SecondActivity.PlaceHolderFragment”的对象，而不是放入类名

像

if(findViewById(R.id.fragment_container) != null) {

if(savedInstanceState != null) {

return;

}
PlaceHolderFragment mFragment = new PlaceHolderFragment();

mFragment.setArguments(getIntent().getExtras());

getSupportFragmentManager().beginTransaction().add(R.id.fragment_container,th
irdFragment).commit();

}

第二件事：

转到类文件PlaceHolderFragment并从“android.support.app.Fragment”更改导入“android.support.v4.app.Fragment”

Answer 6

将import android.support.v4.app.Fragment;更改为import android.app.Fragment;

以及getSupportFragmentManager()到

getFragmentManager
    {
    if (savedInstanceState == null) 
        {
         getFragmentManager().beginTransaction().add(R.id.container, new PlaceholderFragment()).commit();
         }

它对我有用

无法解析方法Android Studio

6 个答案: