阵列适配器强制关闭我的Android应用程序
因此,我尝试实现一个自定义阵列适配器。到目前为止,我已经成功地将它设置为我的ListFragment。然后问题开始出现。我在主xml布局中有一个FrameLayout,我使用FragmentTransaction向其中添加了我的ListFragment(它还没有任何代码)。这是我的密码: 阵列适配器:阵列适配器强制关闭我的Android应用程序,android,eclipse,listview,android-arrayadapter,Android,Eclipse,Listview,Android Arrayadapter,因此,我尝试实现一个自定义阵列适配器。到目前为止,我已经成功地将它设置为我的ListFragment。然后问题开始出现。我在主xml布局中有一个FrameLayout,我使用FragmentTransaction向其中添加了我的ListFragment(它还没有任何代码)。这是我的密码: 阵列适配器: package tj.apps.files; import java.util.ArrayList; import android.app.Activity; import android.c
package tj.apps.files;
import java.util.ArrayList;
import android.app.Activity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;
public class ItemAdapter extends ArrayAdapter<Item> {
int resource;
Context context;
ArrayList<Item> items;
public ItemAdapter(Context context, int resource, ArrayList<Item> items) {
super(context, resource, items);
this.resource = resource;
this.context = context;
this.items = items;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ItemHolder holder = null;
if (convertView == null) {
LayoutInflater inflater = ((Activity) context).getLayoutInflater();
convertView = inflater.inflate(resource, parent, false);
holder = new ItemHolder();
convertView.setClickable(true);
convertView.setFocusable(true);
holder.image= (ImageView) convertView.findViewById(R.id.item_image);
holder.text = (TextView) convertView.findViewById(R.id.item_text);
convertView.setTag(holder);
} else {
holder = (ItemHolder) convertView.getTag();
}
holder.image.setImageResource(R.drawable.search_icon);
holder.text.setText(items.get(position).getName());
return convertView;
}
static class ItemHolder {
ImageView image;
TextView text;
}
}
如果我在主活动中添加setListAdapter方法,应用程序将开始强制关闭。如果我取下它,就不会有力量接近。这里有什么问题 我猜呢?这个电话<代码>fm.findFragmentById(R.id.fragment_listview)代码>找不到具有该id的片段,因此执行以下行时,
listFragment
为空<代码>listFragment.setListAdapter(aa)代码>为什么创建一个片段,然后搜索它?试试这个:ListFragment ListFragment=new ListFragment()
并将listFragment
传递到fm.add()
^Sam尝试了一下,成功了!回到我以前的做法,因为我刚刚向R.id.fragment\u listview容器添加了一个片段,搜索它不会得到我刚才添加的片段的引用,从而允许我为其设置适配器吗?
package tj.apps.files;
import java.util.ArrayList;
import android.os.Bundle;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import com.actionbarsherlock.app.SherlockFragmentActivity;
import com.actionbarsherlock.view.MenuInflater;
import com.actionbarsherlock.view.MenuItem;
public class FilesList extends SherlockFragmentActivity {
private ItemAdapter aa;
private ArrayList<Item> array;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.files_list);
FragmentManager fm = getSupportFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
ft.add(R.id.fragment_listview, new ListFragment());
ft.commit();
array = new ArrayList<Item>();
array.add(new Item("Help"));
aa = new ItemAdapter(this, R.layout.list_item, array);
ListFragment listFragment = (ListFragment) fm.findFragmentById(R.id.fragment_listview);
listFragment.setListAdapter(aa);
}
@Override
public boolean onCreateOptionsMenu(com.actionbarsherlock.view.Menu menu) {
MenuInflater inflater = getSupportMenuInflater();
inflater.inflate(R.menu.files_list, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.menu_search:
return true;
case R.id.menu_edit_mode:
return true;
case R.id.menu_help:
return true;
case R.id.menu_about:
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal" >
<ImageView
android:id="@+id/item_image"
android:layout_width="@dimen/item_size"
android:layout_height="@dimen/item_size"
/>
<TextView
android:id="@+id/item_text"
android:layout_width="match_parent"
android:layout_height="@dimen/item_size"
android:padding="15sp"
android:textSize="@dimen/item_text_size"
/>
</LinearLayout>
11-23 17:26:22.983: E/AndroidRuntime(30582): FATAL EXCEPTION: main
11-23 17:26:22.983: E/AndroidRuntime(30582): java.lang.RuntimeException: Unable to start activity ComponentInfo{tj.apps.files/tj.apps.files.FilesList}: java.lang.NullPointerException
11-23 17:26:22.983: E/AndroidRuntime(30582): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
11-23 17:26:22.983: E/AndroidRuntime(30582): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
11-23 17:26:22.983: E/AndroidRuntime(30582): at android.app.ActivityThread.access$600(ActivityThread.java:130)
11-23 17:26:22.983: E/AndroidRuntime(30582): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
11-23 17:26:22.983: E/AndroidRuntime(30582): at android.os.Handler.dispatchMessage(Handler.java:99)
11-23 17:26:22.983: E/AndroidRuntime(30582): at android.os.Looper.loop(Looper.java:137)
11-23 17:26:22.983: E/AndroidRuntime(30582): at android.app.ActivityThread.main(ActivityThread.java:4745)
11-23 17:26:22.983: E/AndroidRuntime(30582): at java.lang.reflect.Method.invokeNative(Native Method)
11-23 17:26:22.983: E/AndroidRuntime(30582): at java.lang.reflect.Method.invoke(Method.java:511)
11-23 17:26:22.983: E/AndroidRuntime(30582): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
11-23 17:26:22.983: E/AndroidRuntime(30582): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
11-23 17:26:22.983: E/AndroidRuntime(30582): at dalvik.system.NativeStart.main(Native Method)
11-23 17:26:22.983: E/AndroidRuntime(30582): Caused by: java.lang.NullPointerException
11-23 17:26:22.983: E/AndroidRuntime(30582): at tj.apps.files.FilesList.onCreate(FilesList.java:33)
11-23 17:26:22.983: E/AndroidRuntime(30582): at android.app.Activity.performCreate(Activity.java:5008)
11-23 17:26:22.983: E/AndroidRuntime(30582): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
11-23 17:26:22.983: E/AndroidRuntime(30582): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
11-23 17:26:22.983: E/AndroidRuntime(30582): ... 11 more