Question

主要活动

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

 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>

我试图学习片段基础知识。刚在活动中添加了两个按钮。单击一个按钮时，应加载FragmentOne，单击第二个按钮时，FragmentTwo应加载。 MainActivity.java中的以下代码显示错误，错误是不兼容的类型。 FragmentOne和FragmentTwo是我创建的两个片段。 - fragment = new FragmentOne(); - fragment = new FragmentTwo(); 请找到解决方案。谢谢。

Answer 1

在主要活动中，您使用import android.app.Fragment;

FragmentTwo和FragmentOne中的

你使用import android.support.v4.app.Fragment;

您必须决定使用版本更适合您。

链接显示差异： Difference between android.app.Fragment and android.support.v4.app.Fragment

Answer 2

问题是objFragment和fragmentManager之间的片段类型不匹配。第一个来自包android.support.v4.app，而第二个来自android.app package。要解决此问题，请将getFragmentManager()更改为getSupportFragmentManager()。只需替换代码行

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

到

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

我是Android的初学者。不兼容的类型是我尝试创建片段对象时得到的错误

2 个答案: