Question

我正在开发一个显示已安装应用列表的应用。我为这些列表的每个项目添加了复选框以供选择的应用程序问题是当我将其中一个复选框状态设置为选中并向下滚动时，我看到其他一些复选框状态已更改为检查我怎么解决这个问题？？这是我的代码

AllAppsActivity.java代码：

public class AllAppsActivity extends ListActivity {

private PackageManager packageManager = null;
private List<ApplicationInfo> applist = null;
private ApplicationAdapter listadaptor = null;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    packageManager = getPackageManager();

    new LoadApplications().execute();
}


@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
    super.onListItemClick(l, v, position, id);

    if (v != null) {
        CheckBox checkBox = (CheckBox) v.findViewById(R.id.checkBox);
        checkBox.setChecked(!checkBox.isChecked());
    }



}

private List<ApplicationInfo> checkForLaunchIntent(List<ApplicationInfo> list) {
    ArrayList<ApplicationInfo> applist = new ArrayList<ApplicationInfo>();
    for (ApplicationInfo info : list) {
        try {
            if (null != packageManager.getLaunchIntentForPackage(info.packageName)) {
                applist.add(info);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    return applist;
}

private class LoadApplications extends AsyncTask<Void, Void, Void> {
    private ProgressDialog progress = null;

    @Override
    protected Void doInBackground(Void... params) {
        applist = checkForLaunchIntent(packageManager.getInstalledApplications(PackageManager.GET_META_DATA));
        listadaptor = new ApplicationAdapter(AllAppsActivity.this,
                R.layout.snippet_list_row, applist);

        return null;
    }

    @Override
    protected void onCancelled() {
        super.onCancelled();
    }

    @Override
    protected void onPostExecute(Void result) {
        setListAdapter(listadaptor);
        progress.dismiss();
        super.onPostExecute(result);
    }

    @Override
    protected void onPreExecute() {
        progress = ProgressDialog.show(AllAppsActivity.this, null,
                "Loading application info...");
        super.onPreExecute();
    }

    @Override
    protected void onProgressUpdate(Void... values) {
        super.onProgressUpdate(values);
    }
}
}

ApplicationAdapter.java代码：

public class ApplicationAdapter extends ArrayAdapter<ApplicationInfo> {
private List<ApplicationInfo> appsList = null;
private Context context;
private PackageManager packageManager;

public ApplicationAdapter(Context context, int textViewResourceId,
        List<ApplicationInfo> appsList) {
    super(context, textViewResourceId, appsList);
    this.context = context;
    this.appsList = appsList;
    packageManager = context.getPackageManager();
}

@Override
public int getCount() {
    return ((null != appsList) ? appsList.size() : 0);
}

@Override
public ApplicationInfo getItem(int position) {
    return ((null != appsList) ? appsList.get(position) : null);
}

@Override
public long getItemId(int position) {
    return position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    View view = convertView;
    if (null == view) {
        LayoutInflater layoutInflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        view = layoutInflater.inflate(R.layout.snippet_list_row, null);
    }

    ApplicationInfo data = appsList.get(position);
    if (null != data) {
        TextView appName = (TextView) view.findViewById(R.id.app_name);
        TextView packageName = (TextView)   view.findViewById(R.id.app_paackage);
        ImageView iconview = (ImageView) view.findViewById(R.id.app_icon);

        appName.setText(data.loadLabel(packageManager));
        packageName.setText(data.packageName);
        iconview.setImageDrawable(data.loadIcon(packageManager));
    }
    return view;
    }
    };

activity_main.xml文件：

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

<ListView
    android:id="@android:id/list"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content" />

和snippet_list_row.xml代码：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >

<ImageView
    android:id="@+id/app_icon"
    android:layout_width="50dp"
    android:layout_height="50dp"
    android:padding="3dp"
    android:scaleType="centerCrop" />

<LinearLayout
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:gravity="center_vertical"
    android:orientation="vertical"
    android:paddingLeft="5dp" >

    <TextView
        android:id="@+id/app_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="center_vertical"
        android:textStyle="bold" />

    <TextView
        android:id="@+id/app_paackage"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="center_vertical" />
</LinearLayout>

<CheckBox
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/checkBox"
    android:focusable="false" />

</LinearLayout>

Answer 1

您必须跟踪选中的复选框，并使用此选项设置ApplicationAdapter.getView中的选中状态。这将在这一部分

if (null != data) {
        TextView appName = (TextView) view.findViewById(R.id.app_name);
        TextView packageName = (TextView)   view.findViewById(R.id.app_paackage);
        ImageView iconview = (ImageView) view.findViewById(R.id.app_icon);

        appName.setText(data.loadLabel(packageManager));
        packageName.setText(data.packageName);
        iconview.setImageDrawable(data.loadIcon(packageManager));
    }

实施可能是：首先调整Adapter类（双关语），以便在检查项目时能够保留

public class ApplicationAdapter extends ArrayAdapter<ApplicationInfo> {
    ...
+   private SparseArray<Boolean> checkedList = new SparseArray(); 
    ...

+   public void toggleChecked(int position){
+       checkedList.put(position,!checkedList.get(position,false));
+   }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ...

        ApplicationInfo data = appsList.get(position);
        if (null != data) {
            TextView appName = (TextView) view.findViewById(R.id.app_name);
            TextView packageName = (TextView)   view.findViewById(R.id.app_paackage);
            ImageView iconview = (ImageView) view.findViewById(R.id.app_icon);
+           CheckBox checkBox = (CheckBox) v.findViewById(R.id.checkBox);

            appName.setText(data.loadLabel(packageManager));
            packageName.setText(data.packageName);
            iconview.setImageDrawable(data.loadIcon(packageManager));
+           checkBox.setChecked(checkedList.get(position,false);
        }
        return view;
        }
    };

然后需要告诉该项在AllApsActivity的onListItemClicked中被点击，这可能如下所示：

@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
    super.onListItemClick(l, v, position, id);

    if (v != null) {
        CheckBox checkBox = (CheckBox) v.findViewById(R.id.checkBox);
        checkBox.setChecked(!checkBox.isChecked());
+       listadaptor.toggleChecked(position);
    }
}

单击列表项时如何设置选中复选框？

1 个答案: