【发布时间】：2025-12-24 23:05:18
【问题描述】：
我正在开发一个应用程序，它通过复选框向用户显示所有已安装的应用程序。我成功地做到了。但是我在保存和检索用户选择的应用程序时遇到问题。我使用 ArrayList 来存储选定的应用程序，它工作正常，但是当应用程序关闭时，arraylist 中的所有项目都会被删除。然后我通过 SharedPreferences 切换到存储，但我没有工作。最后一个选项是通过 SQLite 数据库存储和检索 applicationInfo 对象，但我不知道如何在数据库中插入和检索 ApplicationInfo 对象。 下面是我的代码（通过 ArrayList 存储）：
main_activity.xml：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
tools:context="com.example.pc.fkidshell.Teen3Activity">
<ListView
android:id="@android:id/list"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="1"/>
<Button
android:id="@+id/btn_add"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:layout_marginBottom="20dp"
android:text="Add Selected Apps"
android:width="170dp"
android:layout_alignParentBottom="true"
android:layout_gravity="center_horizontal" />
</LinearLayout>
row.xml：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal" android:layout_width="fill_parent"
android:layout_height="match_parent">
<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="fill_parent"
android:gravity="center_vertical"
android:orientation="vertical"
android:paddingLeft="5dp" >
<TextView
android:id="@+id/app_name"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center_vertical"
android:textStyle="bold" />
<TextView
android:id="@+id/app_paackage"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center_vertical" />
</LinearLayout>
<CheckBox
android:id="@+id/cb_app"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
main_activity.java：
public class Teen3Activity extends ListActivity {
private PackageManager packageManager = null;
private List<ApplicationInfo> applist = null;
private ApplicationAdapter listadaptor = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_teen3);
Button btn1=(Button) findViewById(R.id.btn_add);
btn1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v)
{
if(MyAddedapss.getAdded_apps().isEmpty())
{
Toast.makeText(getApplicationContext(), "Nothing to ADD!", Toast.LENGTH_LONG).show();
}
else
{
MyAddedapss.writeList(Teen3Activity.this,MyAddedapss.getAdded_apps());
Toast.makeText(getApplicationContext(), "Apps Added!", Toast.LENGTH_LONG).show();
}
}
});
packageManager = getPackageManager();
new LoadApplications().execute();
}
@Override
protected void onListItemClick(ListView l, View v, int position, long id)
{
super.onListItemClick(l, v, position, id);
ApplicationInfo app = applist.get(position);
try {
Intent intent = packageManager.getLaunchIntentForPackage(app.packageName);
if (null != intent) {
startActivity(intent);
}
} catch (ActivityNotFoundException e) {
Toast.makeText(Teen3Activity.this, e.getMessage(), Toast.LENGTH_LONG).show();
} catch (Exception e) {
Toast.makeText(Teen3Activity.this, e.getMessage(), Toast.LENGTH_LONG).show();
}
}
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(Teen3Activity.this, R.layout.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(Teen3Activity.this, null, "Loading application info...");
super.onPreExecute();
}
@Override
protected void onProgressUpdate(Void... values)
{
super.onProgressUpdate(values);
}
}
}
ApplicationAdapter.java:
public class ApplicationAdapter extends ArrayAdapter<ApplicationInfo>
{
private List<ApplicationInfo> appsList = null;
private Context context;
private PackageManager packageManager;
private ArrayList<Boolean> checkList = new ArrayList<Boolean>();
public ApplicationAdapter(Context context, int textViewResourceId, List<ApplicationInfo> appsList)
{
super(context, textViewResourceId, appsList);
this.context = context;
this.appsList = appsList;
packageManager = context.getPackageManager();
for (int i = 0; i < appsList.size(); i++) {
checkList.add(false);
}
}
@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.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);
CheckBox checkBox = (CheckBox) view.findViewById(R.id.cb_app);
checkBox.setTag(Integer.valueOf(position)); // set the tag so we can identify the correct row in the listener
checkBox.setChecked(checkList.get(position));// set the status as we stored it
checkBox.setOnCheckedChangeListener(mListener); // set the listener
appName.setText(data.loadLabel(packageManager));
packageName.setText(data.packageName);
iconview.setImageDrawable(data.loadIcon(packageManager));
}
return view;
}
CompoundButton.OnCheckedChangeListener mListener = new CompoundButton.OnCheckedChangeListener()
{
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked)
{
checkList.set((Integer)buttonView.getTag(),isChecked); // get the tag so we know the row and store the status
if(isChecked)
{
int addapppos = (Integer) buttonView.getTag();
ApplicationInfo p=appsList.get(addapppos);
MyAddedapss.setAdded_apps(p);
buttonView.setEnabled(false);
}
}
};
}
MyAddedApps.java：（用于存储用户选择的应用程序的类）
public class MyAddedapss extends Application
{
private static ArrayList<ApplicationInfo> added_apps=new ArrayList<ApplicationInfo>();
public static void setAdded_apps(ApplicationInfo element)
{
added_apps.add(element);
}
public static ArrayList<ApplicationInfo> getAdded_apps()
{
return added_apps;
}
public static boolean remove_app(ApplicationInfo element)
{
return added_apps.remove(element);
}
}
【问题讨论】：
标签： java android sqlite android-studio arraylist