我有从json解析器在哈希映射中排序的应用程序列表。当我尝试查看应用程序信息onClick时，它崩溃了这里的代码
请记住，我有其他应用类别的其他列表视图
public class iqa extends Fragment {
ListView communication;
ArrayList<HashMap<String, String>> communicationlist = new ArrayList<HashMap<String, String>>();
public class now extends AsyncTask <HttpURLConnection, Void,Void> implements AdapterView.OnItemClickListener {
//returns app name using package name as input
public String appName(String pack){
String Name = null;
try{
PackageManager packManager = getContext().getPackageManager();
ApplicationInfo app = getContext().getPackageManager().getApplicationInfo(pack, 0);
Name = packManager.getApplicationLabel(app).toString();
}
catch(Exception e){
e.printStackTrace();
}
return Name;
}
private void getAppCategories() throws IOException, JSONException
{
BufferedReader bufferedReader = null;
HttpURLConnection urlConnection = null;
BufferedWriter bufferedWriter = null;
StringBuilder result = new StringBuilder();
//Create JSON object to send to webservice
JSONObject jsonObjectSend = new JSONObject();
JSONArray jsonArrayPakages = new JSONArray();
PackageManager packageManager;
List<ResolveInfo> listApps; //this list store all app in device
try {
packageManager = getActivity().getPackageManager();
Intent filterApp = new Intent(Intent.ACTION_MAIN);
filterApp.addCategory(Intent.CATEGORY_LAUNCHER);
listApps = packageManager.queryIntentActivities(filterApp, PackageManager.GET_META_DATA);
for (ResolveInfo app : listApps){
jsonArrayPakages.put(app.activityInfo.packageName.trim());
}
jsonObjectSend.put("packages", jsonArrayPakages);
Log.d("json", jsonObjectSend.toString());
URL url = new URL("http://getdatafor.appspot.com/data?key=53972606b926d38191a5446fdff89e377873d767fabedf6d");
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setConnectTimeout(30000); /* milliseconds */
urlConnection.setReadTimeout(30000); /* milliseconds */
urlConnection.setRequestMethod("POST");
urlConnection.setRequestProperty("Content-Type", "application-json");
urlConnection.setDoOutput(true); /* allow output to send data */
urlConnection.connect();
OutputStream outputStream = urlConnection.getOutputStream();
bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream));
bufferedWriter.write(jsonObjectSend.toString());
bufferedWriter.flush();
InputStream inputStream = urlConnection.getInputStream();
bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
//Read data
String line;
while ((line = bufferedReader.readLine()) != null) {
result.append(line);
}
/*Parse JSON**********************************************************************************/
JSONObject jsonObjectResult = new JSONObject(result.toString().trim());
JSONArray jsonArrayApps = jsonObjectResult.getJSONArray("apps");
for (int j = 0; j < jsonArrayApps.length(); j++) {
JSONObject jsonObjectApp = jsonArrayApps.getJSONObject(j);
String packageName = jsonObjectApp.getString("package").trim();
String cate = jsonObjectApp.getString("category").trim();
Log.d("result", (j + 1) + "---> : " + packageName + "---" + cate);
HashMap<String, String> communicationmap = new HashMap<String, String>();
String Communication = "Communication";
String ca = e.getString("category").trim();
String vit = e.getString("package").trim();
String va = appName(vit);
if (ca.equals(Communication) || ca.equals(Social) || ca.equals(dat))
{
boolean communicexist = communicationmap.containsValue(va);
if (communicexist == false)
{
communicationmap.put("Name", va);
communicationmap.put("cate", ca);
communicationlist.add(communicationmap);
}
else
{
cmap.put("Name", va);
cmap.put("cate", ca);
}
}
finally {
if (bufferedReader != null) {
bufferedReader.close();
}
if (bufferedWriter != null) {
bufferedWriter.close();
}
if (urlConnection != null) {
urlConnection.disconnect();
}
}
}
@Override
protected Void doInBackground(HttpURLConnection... params) {
try {
getAppCategories();
} catch (IOException e) {
Log.d("tag", "Net work error: " + e.getMessage(), e);
} catch (JSONException e) {
Log.d("tag", "JSON is not valid: " + e.getMessage(), e);
}
return null;
}
@Override
protected void onPostExecute(Void aVoid) {
// Keys used in Hashmap
String[] from = { "Name","cate" };
// Ids of views in listview_layout
int[] to = { R.id.packa,R.id.catego};
ListAdapter communicationadapter = new SimpleAdapter(getActivity().getBaseContext(), communicationlist,R.layout.lay,from,to);
communication.setAdapter(communicationadapter);
communication.setOnItemClickListener(this);
Utility.setListViewHeightBasedOnChildren(communication);
super.onPostExecute(aVoid);
}
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
//THIS IS WHERE THE ERROR STARTS
PackageInfo packageInfo = (PackageInfo) parent.getItemAtPosition(position);
AppData appData = (AppData) getActivity().getApplicationContext();
appData.setPackageInfo(packageInfo);
try {
Intent appInfo = new Intent(getActivity().getApplicationContext(), permdisabled.class);
startActivity(appInfo);
}
catch (Exception e)
{
Log.e(TAG, "error in intent");
}
}
}
OnItemClick适配器是错误开始的地方
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
PackageInfo packageInfo = (PackageInfo) parent.getItemAtPosition(position);
AppData appData = (AppData) getActivity().getApplicationContext();
appData.setPackageInfo(packageInfo);
try {
Intent appInfo = new Intent(getActivity().getApplicationContext(), permdisabled.class);
startActivity(appInfo);
}
catch (Exception e)
{
Log.e(TAG, "error in intent");
}
}
实施后，就像这样
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
HashMap<String,String> clickedItem = (HashMap<String, String>) parent.getItemAtPosition(position);
String packageName = clickedItem.get("package");
try {
PackageManager packManager = getContext().getPackageManager();
ApplicationInfo app = getContext().getPackageManager().getApplicationInfo(packageName, 0);
String appName = packManager.getApplicationLabel(app).toString();
PackageInfo packageInfo = (PackageInfo) parent.getItemAtPosition(position);
AppData appData = (AppData) getActivity().getApplicationContext();
appData.setPackageInfo(packageInfo);
}
catch (Exception e)
{
e.printStackTrace();
}
try {
Intent appInfo = new Intent(getActivity().getApplicationContext(), permdisabled.class);
startActivity(appInfo);
}
catch (Exception e)
{
Log.e(TAG, "error in intent");
}
}
我收到以下错误
FATAL EXCEPTION: main
Process: com.finalyearstudentvitus.splash, PID: 25698
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.finalyearstudentvitus.splash/com.finalyearstudentvitus.splash.permdisabled}: java.lang.NullPointerException: Attempt to read from field 'android.content.pm.ApplicationInfo android.content.pm.PackageInfo.applicationInfo' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2724)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2789)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1527)
at android.os.Handler.dispatchMessage(Handler.java:110)
at android.os.Looper.loop(Looper.java:203)
at android.app.ActivityThread.main(ActivityThread.java:6251)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1073)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:934)
Caused by: java.lang.NullPointerException: Attempt to read from field 'android.content.pm.ApplicationInfo android.content.pm.PackageInfo.applicationInfo' on a null object reference
at com.finalyearstudentvitus.splash.permdisabled.setValues(permdisabled.java:44)
at com.finalyearstudentvitus.splash.permdisabled.onCreate(permdisabled.java:31)
at android.app.Activity.performCreate(Activity.java:6686)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2677)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2789)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1527)
at android.os.Handler.dispatchMessage(Handler.java:110)
at android.os.Looper.loop(Looper.java:203)
at android.app.ActivityThread.main(ActivityThread.java:6251)
at java.lang.reflect.Method.invoke(Native Method)
以下是permdisabled.java类
public class permdisabled extends Activity {
TextView appLabel, packageName;
TextView req_permission, diss_perission;
PackageInfo packageInfo;
String pass;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.permdisabled);
findViewsById();
AppData appData = (AppData) getApplicationContext();
packageInfo = appData.getPackageInfo();
setValues();
}
private void findViewsById() {
appLabel = (TextView) findViewById(R.id.appplabel);
packageName = (TextView) findViewById(R.id.packagee_name);
req_permission = (TextView) findViewById(R.id.req_permissionn);
diss_perission = (TextView) findViewById(R.id.diss_permissionn);
}
private void setValues()
{
// APP name ERROR STARTS HERE
appLabel.setText(getPackageManager().getApplicationLabel(
packageInfo.applicationInfo));
// package name
packageName.setText(packageInfo.packageName);
// uses-permission
if (packageInfo.requestedPermissions != null) {
req_permission.setText(getPermissions(packageInfo.requestedPermissions));
pass = req_permission.toString();
}
else {
req_permission.setText("-");
}
}
// Convert string array to comma separated string
private String getPermissions(String[] requestedPermissions) {
String permission = "";
for (int i = 0; i < requestedPermissions.length; i++) {
permission = permission + requestedPermissions[i] + ",\n";
}
return permission;
}
}
答案 0 :(得分：1)
尝试实施以下内容：
// Modify your HashMap like this
if (communicexist == false)
{
communicationmap.put("package", vit);
communicationmap.put("cate", ca);
communicationlist.add(communicationmap);
}
else
{
cmap.put("package", vit);
cmap.put("cate", ca);
}
然后在onItemClick，
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
HashMap<String,String> clickedItem = parent.getItemAtPosition(position);
String packageName = clickedItem.get("package");
try{
PackageManager packManager = getContext().getPackageManager();
ApplicationInfo app = getContext().getPackageManager().getApplicationInfo(packageName , 0);
String appName = packManager.getApplicationLabel(app).toString();
AppData appData = (AppData) getActivity().getApplicationContext();
appData.setPackageInfo(packageInfo);
}
catch(Exception e){
e.printStackTrace();
}
try {
Intent appInfo = new Intent(getActivity().getApplicationContext(), permdisabled.class);
startActivity(appInfo);
}
catch (Exception e)
{
Log.e(TAG, "error in intent");
}
}