Android ArrayAdapter：将片段添加到行工作错误

Question

我正在使用带有 ArrayAdapter 的 ListView 并尝试将片段添加到 ListView 的所有行。但是，该应用程序无法正常工作：屏幕上只有一行显示了添加的片段，而不是所有行。有时应用程序可能会因为内存不足而崩溃。

谁能给我一些建议？谢谢。

MainActivity.java

package com.me.test05;

import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentTransaction;
import android.content.Context;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        if (savedInstanceState == null) {
            ListView myListView = (ListView) findViewById(R.id.myListView);
            myListView.setAdapter(new MyArrayAdaptor(this, R.layout.row));
        }
    }

    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;
        }
    }

    private static final String[] allnames = { "John", "Marry", "Smith", "Felicity", "Lion", "Math" };

    public static class MyArrayAdaptor extends ArrayAdapter<String> {
        private final Context context;

        public MyArrayAdaptor(Context context, int resource) {
            super(context, resource);
            this.context = context;
        }

        @Override
        public int getCount() {
            return allnames.length * 100;
        }

        @Override
        public String getItem(int position) {
            return allnames[position % allnames.length];
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            View rowView = inflater.inflate(R.layout.row, parent, false);

            TextView textView = (TextView) rowView.findViewById(R.id.textView1);
            String str = getItem(position);
            textView.setText(str);

            FragmentTransaction ft = ((Activity) context).getFragmentManager().beginTransaction();
            ft.replace(R.id.myFrameLayout, new PlaceholderFragment());
            ft.commit();

            return rowView;
        }
    }
}

文件activity.xml：

<merge xmlns:android="http://schemas.android.com/apk/res/android"
    android:fitsSystemWindows="true">

    <ListView android:id="@+id/myListView" 
       android:layout_height="fill_parent"
       android:layout_width="fill_parent"
       android:dividerHeight="2px">
    </ListView>

</merge>

文件行.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="abc" />

    <FrameLayout
        android:id="@+id/myFrameLayout"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        >
    </FrameLayout>

</LinearLayout>

文件fragment_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="horizontal" >

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/textView1"
        android:layout_below="@+id/textView1"
        android:text="Button" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />


</LinearLayout>

画面如下：

Answer 1

我已经解决了这个问题。问题是片段管理器总是在全局中找到（用新片段替换）一个 id。这就是为什么它总是找到所有新片段并将其添加到第一行，因为它是第一个包含该 ID（以及所有其他行）的片段。

为了解决这个问题，我为每一行创建了唯一的动态 id，然后用它们替换固定的 id，然后让片段管理器完成剩下的工作。我还将这些动态 id 存储到行的标签中以供后者重用。

新代码如下，包括查找和重用添加的片段的代码：

package com.me.test05;

import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentTransaction;
import android.content.Context;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.FrameLayout;
import android.widget.ListView;
import android.widget.TextView;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        if (savedInstanceState == null) {
            ListView myListView = (ListView) findViewById(R.id.myListView);
            myListView.setAdapter(new MyArrayAdaptor(this, R.layout.row));
        }
    }

    public static class PlaceholderFragment extends Fragment {
        private View rootView = null;
        private String theString = null;

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

            return rootView;
        }

        public void setString(String str) {
            theString = str;
            if (theString != null && rootView != null) {
                TextView textView = (TextView) rootView.findViewById(R.id.textView2);
                textView.setText(str);
            }
        }
    }

    private static final String[] allnames = { "John", "Marry", "Smith", "Felicity", "Lion", "Math" };

    public static class MyArrayAdaptor extends ArrayAdapter<String> {
        private final Context context;

        public MyArrayAdaptor(Context context, int resource) {
            super(context, resource);
            this.context = context;
        }

        @Override
        public int getCount() {
            return allnames.length * 100;
        }

        @Override
        public String getItem(int position) {
            return allnames[position % allnames.length];
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            View rowView = convertView;

            PlaceholderFragment myFragment = null;
            if (rowView == null) {
                rowView = inflater.inflate(R.layout.row, parent, false);

                int newId = 100000 + position;
                FrameLayout layout = (FrameLayout) rowView.findViewById(R.id.myFrameLayout);
                layout.setId(newId);
                rowView.setTag(newId);

                myFragment = new PlaceholderFragment();
                FragmentTransaction ft = ((Activity) context).getFragmentManager().beginTransaction();
                ft.replace(newId, myFragment, "" + newId).commit();
            } else {
                Integer theId = (Integer) convertView.getTag();
                myFragment = (PlaceholderFragment) ((Activity) context).getFragmentManager().findFragmentById(theId);
            }
            String str = getItem(position);
            myFragment.setString(str + ", " + position);

            TextView textView = (TextView) rowView.findViewById(R.id.textView1);
            textView.setText(str);

            return rowView;
        }
    }
}