Question

嘿大家我只是想跟随一个关于开发Android项目的课程但是在这里我遇到了一个障碍（错误）。但是我输入了每一段代码，因为它在我遇到这个错误的过程中。

Error:(19, 21) error: no suitable method found for add(int,PlaceholderFragment)
method FragmentTransaction.add(Fragment,String) is not applicable
(argument mismatch; int cannot be converted to Fragment)
method FragmentTransaction.add(int,Fragment) is not applicable
(argument mismatch; PlaceholderFragment cannot be converted to Fragment)

这是我的activity_main布局文件：

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.recreated.wedowhatwelearn.MainActivity"
   tools:ignore="MergeRootFrame"/>

这是我的fragment_main.xml布局文件：

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.recreated.wedowhatwelearn.MainActivity$PlaceHolderFragment">

    <ListView android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/listviewsorular" />


</FrameLayout>

最后这是我的MainActivity.java文件

package com.example.recreated.wedowhatwelearn;

import android.app.Fragment;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
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 1

您的PlaceholderFragment是android.app.Fragment。由于您使用的是支持FragmentManager（通过getSupportFragmentManager()），因此需要android.support.v4.app.Fragment。

只需更改导入即可，一切正常。

android studio没有合适的.add方法

1 个答案: