我是Android的初學者。不兼容的類型是我得到當我試圖創建片段的目的

Question

主要活動

package com.example.richu.fragment; 
import android.app.Fragment; 
import android.app.FragmentManager; 
import android.app.FragmentTransaction; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.view.View; 

public class MainActivity extends AppCompatActivity { 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
} 
public void changeFragment(View view){ 
    Fragment fragment; 
    if(view == findViewById(R.id.button3)){ 
     fragment = new FragmentOne(); 
     FragmentManager fm = getFragmentManager(); 
     FragmentTransaction ft = fm.beginTransaction(); 
     ft.replace(R.id.fragment1,fragment); 
     ft.commit(); 
    } 
    if(view == findViewById(R.id.button4)){ 
     fragment = new FragmentTwo(); 
     FragmentManager fm = getFragmentManager(); 
     FragmentTransaction ft = fm.beginTransaction(); 
     ft.replace(R.id.fragment1,fragment); 
     ft.commit(); 
    } 
} 
} 

MainActivity.xml

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:app="http://schemas.android.com/apk/res-auto" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    tools:context="com.example.richu.fragment.MainActivity"> 

    <Button 
     android:id="@+id/button3" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="Button" 
     tools:layout_editor_absoluteX="2dp" 
     tools:layout_editor_absoluteY="5dp" /> 

    <Button 
     android:id="@+id/button4" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="Button" 
     tools:layout_editor_absoluteX="292dp" 
     tools:layout_editor_absoluteY="5dp" /> 

    <fragment 
     android:id="@+id/fragment1" 
     android:name="layout.FragmentOne" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     tools:layout_editor_absoluteX="13dp" 
     tools:layout_editor_absoluteY="13dp" /> 
</LinearLayout> 

FragmentOne.java錯誤

package layout; 
    import android.content.Context; 
     import android.net.Uri; 
     import android.os.Bundle; 
     import android.support.v4.app.Fragment; 
     import android.view.LayoutInflater; 
     import android.view.View; 
     import android.view.ViewGroup; 

     import com.example.richu.fragment.R; 


     public class FragmentOne extends Fragment { 

     @Override 
     public View onCreateView(LayoutInflater inflater, ViewGroup container, 
           Bundle savedInstanceState) { 
      // Inflate the layout for this fragment 
      return inflater.inflate(R.layout.fragment_fragment_one, container, false); 
     } 

     } 

FragmentOne.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:background="@color/colorAccent" 
    tools:context="layout.FragmentOne"> 


</FrameLayout> 

FragmentTwo.java

package layout; 

import android.content.Context; 
import android.net.Uri; 
import android.os.Bundle; 
import android.support.v4.app.Fragment; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 

import com.example.richu.fragment.R; 

public class FragmentTwo extends Fragment { 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
          Bundle savedInstanceState) { 
     // Inflate the layout for this fragment 
     return inflater.inflate(R.layout.fragment_fragment_two, container, false); 
    } 


} 

FragmentTwo.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:background="@color/colorAccent" 
    tools:context="layout.FragmentTwo"> 


    <TextView 
     android:id="@+id/textView" 
     android:layout_width="match_parent" 
     android:layout_height="50dp" 
     android:text="Hello" /> 
</FrameLayout> 

我在學習片段基礎知識。剛在活動中添加了兩個按鈕。當單擊一個按鈕時，應該加載FragmentOne，並在單擊第二個按鈕時加載FragmentTwo。 MainActivity.java中的以下代碼顯示錯誤，並且錯誤爲不兼容的類型。 FragmentOne和FragmentTwo是我創建的兩個片段。 - fragment = new FragmentOne(); - fragment = new FragmentTwo(); 請爲此找到解決方案。謝謝。

Answer 1

在主要活動中，您使用import android.app.Fragment;

in FragmentTwo and FragmentOne您可以使用import android.support.v4.app.Fragment;

你必須決定版本更適合你。

鏈接示區別： Difference between android.app.Fragment and android.support.v4.app.Fragment

Answer 2

的問題是，有在objFragment和fragmentManager之間的片段類型的失配。第一個來自包android.support.v4.app，而第二個來自android.app package。要解決該問題，請將getFragmentManager()更改爲getSupportFragmentManager()。只需更換行代碼

FragmentManager fm = getFragmentManager(); 
    FragmentTransaction ft = fm.beginTransaction(); 

到

android.support.v4.app.FragmentManager fm = getSupportFragmentManager(); 
    android.support.v4.app.FragmentTransaction ft = fm.beginTransaction();