我正在使用json在第一个活动上制作一个应用程序，但是当应用程序打开而没有互联网连接时，应用程序会“强制关闭”，我不知道该怎么办卵形这个错误，帮助，我在android和java上的新功能
公共类MainActivity扩展了ActionBarActivity {
String TITLES[] = {"Que es CMX","Ejecutivos(as)","Nuestros Servicios","Soluciones a tu Medida","Certificaciones Vigentes", "Cursos Online", "", "", "", ""};
int ICONS[] = {R.mipmap.organization,R.mipmap.conference,R.mipmap.services,R.mipmap.approval,R.mipmap.diploma1,R.mipmap.donate,R.id.linea,R.id.linea,R.id.linea,R.mipmap.home};
String NAME = "John Doe";
String EMAIL = "johndoe@cmx.org.mx";
int PROFILE = R.drawable.profile1;
private Toolbar toolbar; // Declaring the Toolbar Object
RecyclerView mRecyclerView; // Declaring RecyclerView
RecyclerView.Adapter mAdapter; // Declaring Adapter For Recycler View
RecyclerView.LayoutManager mLayoutManager; // Declaring Layout Manager as a linear layout manager
DrawerLayout Drawer; // Declaring DrawerLayout
ActionBarDrawerToggle mDrawerToggle; // Declaring Action Bar Drawer Toggle
// Declare Variables
JSONObject jsonobject;
JSONArray jsonarray;
ListView listview;
ListViewAdapter adapter;
ProgressDialog mProgressDialog;
ArrayList<HashMap<String, String>> arraylist;
static String RANK = "title";
static String COUNTRY = "place";
static String POPULATION = "date";
static String CONTENT1 = "content1";
static String CONTENT2 = "content2";
static String FLAG = "imagen";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Get the view from listview_main.xml
setContentView(R.layout.listview_main);
// Execute DownloadJSON AsyncTask
new DownloadJSON().execute();
toolbar = (Toolbar) findViewById(R.id.tool_bar);
setSupportActionBar(toolbar);
setTitle(R.string.title_activity_main);
mRecyclerView = (RecyclerView) findViewById(R.id.RecyclerView); // Assigning the RecyclerView Object to the xml View
mRecyclerView.setHasFixedSize(true); // Letting the system know that the list objects are of fixed size
mAdapter = new MyAdapter(TITLES,ICONS,NAME,EMAIL,PROFILE,this); // Creating the Adapter of MyAdapter class(which we are going to see in a bit)
// And passing the titles,icons,header view name, header view email,
// and header view profile picture
mRecyclerView.setAdapter(mAdapter); // Setting the adapter to RecyclerView
final GestureDetector mGestureDetector = new GestureDetector(MainActivity.this, new GestureDetector.SimpleOnGestureListener() {
@Override public boolean onSingleTapUp(MotionEvent e) {
return true;
}
});
mRecyclerView.addOnItemTouchListener(new RecyclerView.OnItemTouchListener() {
@Override
public boolean onInterceptTouchEvent(RecyclerView recyclerView, MotionEvent motionEvent) {
View child = recyclerView.findChildViewUnder(motionEvent.getX(),motionEvent.getY());
if(child !=null && mGestureDetector.onTouchEvent(motionEvent)){
Drawer.closeDrawers();
if (recyclerView.getChildPosition(child) == 0) {
Intent intent = new Intent(MainActivity.this, Profile.class);
startActivity(intent);
finish();
}else if
(recyclerView.getChildPosition(child) == 1) {
Intent intent = new Intent(MainActivity.this, CMX.class);
startActivity(intent);
finish();
}else if
(recyclerView.getChildPosition(child) == 2) {
Intent intent = new Intent(MainActivity.this, Ejecutivos.class);
startActivity(intent);
finish();
}else if
(recyclerView.getChildPosition(child) == 3){
Intent intent = new Intent(MainActivity.this, Servicios.class);
startActivity(intent);
finish();
}else if
(recyclerView.getChildPosition(child) == 4){
Intent intent = new Intent(MainActivity.this, Soluciones.class);
startActivity(intent);
finish();
}else if
(recyclerView.getChildPosition(child) == 5) {
Intent intent = new Intent(MainActivity.this, Certificaciones.class);
startActivity(intent);
finish();
}else if
(recyclerView.getChildPosition(child) == 6){
Intent intent = new Intent(MainActivity.this, Web.class);
startActivity(intent);
finish();
}else if
(recyclerView.getChildPosition(child) == 8 ){
Intent intent = new Intent(MainActivity.this, MainActivity.class);
startActivity(intent);
finish();
}
return true;
}
return false;
}
@Override
public void onTouchEvent(RecyclerView recyclerView, MotionEvent motionEvent) {
}
});
mLayoutManager = new LinearLayoutManager(this); // Creating a layout Manager
mRecyclerView.setLayoutManager(mLayoutManager); // Setting the layout Manager
Drawer = (DrawerLayout) findViewById(R.id.DrawerLayout); // Drawer object Assigned to the view
mDrawerToggle = new ActionBarDrawerToggle(this,Drawer,toolbar,R.string.openDrawer,R.string.closeDrawer){
@Override
public void onDrawerOpened(View drawerView) {
super.onDrawerOpened(drawerView);
// code here will execute once the drawer is opened( As I dont want anything happened whe drawer is
// open I am not going to put anything here)
}
@Override
public void onDrawerClosed(View drawerView) {
super.onDrawerClosed(drawerView);
// Code here will execute once drawer is closed
}
}; // Drawer Toggle Object Made
Drawer.setDrawerListener(mDrawerToggle); // Drawer Listener set to the Drawer toggle
mDrawerToggle.syncState(); // Finally we set the drawer toggle sync State
}
// DownloadJSON AsyncTask
private class DownloadJSON extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
// Create a progressdialog
mProgressDialog = new ProgressDialog(MainActivity.this);
// Set progressdialog message
mProgressDialog.setMessage("Cargando...");
mProgressDialog.setIndeterminate(false);
// Show progressdialog
mProgressDialog.show();
}
@Override
protected Void doInBackground(Void... params) {
// Create an array
arraylist = new ArrayList<HashMap<String, String>>();
// Retrieve JSON Objects from the given URL address
jsonobject = JSONfunctions.getJSONfromURL("http://cmx.org.mx/wp-content/uploads/json.txt");
try {
// Locate the array name in JSON
jsonarray = jsonobject.getJSONArray("posts");
for (int i = 0; i < jsonarray.length(); i++) {
HashMap<String, String> map = new HashMap<String, String>();
jsonobject = jsonarray.getJSONObject(i);
// Retrive JSON Objects
map.put("title", jsonobject.getString("title"));
map.put("place", jsonobject.getString("place"));
map.put("date", jsonobject.getString("date"));
map.put("content1", jsonobject.getString("content1"));
map.put("content2", jsonobject.getString("content2"));
map.put("imagen", jsonobject.getString("imagen"));
// Set the JSON Objects into the array
arraylist.add(map);
}
} catch (JSONException e) {
Log.e("Error", e.getMessage());
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Void args) {
// Locate the listview in listview_main.xml
listview = (ListView) findViewById(R.id.listview);
// Pass the results into ListViewAdapter.java
adapter = new ListViewAdapter(MainActivity.this, arraylist);
// Set the adapter to the ListView
listview.setAdapter(adapter);
// Close the progressdialog
mProgressDialog.dismiss();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
if (mDrawerToggle.onOptionsItemSelected(item)) {
return true;
}
switch (item.getItemId()) {
// Respond to the action bar's Up/Home button
case R.id.about:
Intent intent = new Intent(MainActivity.this, About.class);
startActivity(intent);
return true;
}
return super.onOptionsItemSelected(item);
}
}
public class JSONfunctions {
public static JSONObject getJSONfromURL(String url) {
InputStream is = null;
String result = "";
JSONObject jArray = null;
// Download JSON data from URL
try {
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(url);
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
} catch (Exception e) {
Log.e("log_tag", "Error in http connection " + e.toString());
}
// Convert response to string
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
result = sb.toString();
} catch (Exception e) {
Log.e("log_tag", "Error converting result " + e.toString());
}
try {
jArray = new JSONObject(result);
} catch (JSONException e) {
Log.e("log_tag", "Error parsing data " + e.toString());
}
return jArray;
}
}
- 编辑
logcat的： https://goo.gl/N1YQ9T
UPDATE1：
@Override
protected Void doInBackground(Void... params) {
// Create an array
arraylist = new ArrayList<HashMap<String, String>>();
// Retrieve JSON Objects from the given URL address
jsonobject = JSONfunctions.getJSONfromURL("http://cmx.org.mx/wp-content/uploads/json.txt");
if(jsonobject==null){
Toast.makeText(getApplicationContext(), "No Internet", Toast.LENGTH_LONG).show();
}else{
try {
// Locate the array name in JSON
jsonarray = jsonobject.getJSONArray("posts");
for (int i = 0; i < jsonarray.length(); i++) {
HashMap<String, String> map = new HashMap<String, String>();
jsonobject = jsonarray.getJSONObject(i);
// Retrive JSON Objects
map.put("title", jsonobject.getString("title"));
map.put("place", jsonobject.getString("place"));
map.put("date", jsonobject.getString("date"));
map.put("content1", jsonobject.getString("content1"));
map.put("content2", jsonobject.getString("content2"));
map.put("imagen", jsonobject.getString("imagen"));
// Set the JSON Objects into the array
arraylist.add(map);
}
} catch (JSONException e) {
Log.e("Error", e.getMessage());
e.printStackTrace();
}
}
return null;
}
MyAdapter：
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {
private static final int TYPE_HEADER = 0; // Declaring Variable to Understand which View is being worked on
// IF the view under inflation and population is header or Item
private static final int TYPE_ITEM = 1;
private String mNavTitles[]; // String Array to store the passed titles Value from MainActivity.java
private int mIcons[]; // Int Array to store the passed icons resource value from MainActivity.java
private String name; //String Resource for header View Name
private int profile; //int Resource for header view profile picture
private String email; //String Resource for header view email
Context context;
// Creating a ViewHolder which extends the RecyclerView View Holder
// ViewHolder are used to to store the inflated views in order to recycle them
public static class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
int Holderid;
TextView textView;
ImageView imageView;
ImageView profile;
TextView Name;
TextView email;
Context contxt;
public ViewHolder(View itemView,int ViewType,Context c) { // Creating ViewHolder Constructor with View and viewType As a parameter
super(itemView);
contxt = c;
itemView.setClickable(true);
itemView.setOnClickListener(this);
// Here we set the appropriate view in accordance with the the view type as passed when the holder object is created
if(ViewType == TYPE_ITEM) {
textView = (TextView) itemView.findViewById(R.id.rowText); // Creating TextView object with the id of textView from item_row.xml
imageView = (ImageView) itemView.findViewById(R.id.rowIcon);// Creating ImageView object with the id of ImageView from item_row.xml
Holderid = 1; // setting holder id as 1 as the object being populated are of type item row
}
else{
Name = (TextView) itemView.findViewById(R.id.name); // Creating Text View object from header.xml for name
email = (TextView) itemView.findViewById(R.id.email); // Creating Text View object from header.xml for email
profile = (ImageView) itemView.findViewById(R.id.circleView);// Creating Image view object from header.xml for profile pic
Holderid = 0; // Setting holder id = 0 as the object being populated are of type header view
}
}
@Override
public void onClick(View v) {
Toast.makeText(contxt, "The Item Clicked is: " + getPosition(), Toast.LENGTH_SHORT).show();
}
}
MyAdapter(String Titles[],int Icons[],String Name,String Email, int Profile, Context passedContext){ // MyAdapter Constructor with titles and icons parameter
// titles, icons, name, email, profile pic are passed from the main activity as we
mNavTitles = Titles; //have seen earlier
mIcons = Icons;
name = Name;
email = Email;
profile = Profile;
this.context = passedContext; //here we assign those passed values to the values we declared here
//in adapter
}
//Below first we ovverride the method onCreateViewHolder which is called when the ViewHolder is
//Created, In this method we inflate the item_row.xml layout if the viewType is Type_ITEM or else we inflate header.xml
// if the viewType is TYPE_HEADER
// and pass it to the view holder
@Override
public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (viewType == TYPE_ITEM) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_row,parent,false); //Inflating the layout
ViewHolder vhItem = new ViewHolder(v,viewType,context); //Creating ViewHolder and passing the object of type view
return vhItem; // Returning the created object
//inflate your layout and pass it to view holder
} else if (viewType == TYPE_HEADER) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.header,parent,false); //Inflating the layout
ViewHolder vhHeader = new ViewHolder(v,viewType,context); //Creating ViewHolder and passing the object of type view
return vhHeader; //returning the object created
}
return null;
}
//Next we override a method which is called when the item in a row is needed to be displayed, here the int position
// Tells us item at which position is being constructed to be displayed and the holder id of the holder object tell us
// which view type is being created 1 for item row
@Override
public void onBindViewHolder(MyAdapter.ViewHolder holder, int position) {
if(holder.Holderid ==1) { // as the list view is going to be called after the header view so we decrement the
// position by 1 and pass it to the holder while setting the text and image
holder.textView.setText(mNavTitles[position - 1]); // Setting the Text with the array of our Titles
holder.imageView.setImageResource(mIcons[position -1]);// Settimg the image with array of our icons
}
else{
holder.profile.setImageResource(profile); // Similarly we set the resources for header view
holder.Name.setText(name);
holder.email.setText(email);
}
}
// This method returns the number of items present in the list
@Override
public int getItemCount() {
return mNavTitles.length+1; // the number of items in the list will be +1 the titles including the header view.
}
// Witht the following method we check what type of view is being passed
@Override
public int getItemViewType(int position) {
if (isPositionHeader(position))
return TYPE_HEADER;
return TYPE_ITEM;
}
private boolean isPositionHeader(int position) {
return position == 0;
}
答案 0 :(得分：0)
你的方法getJSONfromURL()捕获了我能想到的所有异常，所以问题可能不存在。
问题是，当捕获到异常时，它会返回null。
因此，当您没有互联网时，jsonobject为空，然后您正在访问它，好像它在jsonobject.getJSONArray("posts")处不为空。
我建议您检查jsonobject == null
jsonobject = JSONfunctions.getJSONfromURL(...);是否int ICONS[] = {R.mipmap.organization,R.mipmap.conference,R.mipmap.services,R.mipmap.approval,R.mipmap.diploma1,R.mipmap.donate,R.id.linea,R.id.linea,R.id.linea,R.mipmap.home};
修改（以下评论）：
错误可能是由于MainActivity中的这行代码造成的。
ICONS
R.id.linea数组中的所有项目应该是R.mipmap.xxxx或R.drawable.xxxx，而不是R.id.xxxx或其他项目。要查看是否存在此问题，请将所有R.mipmap.conference替换为{{1}}以进行测试，并告知我们当时会发生什么。
答案 1 :(得分：0)
@Override
protected Void doInBackground(Void... params) {
// Create an array
arraylist = new ArrayList<HashMap<String, String>>();
// Retrieve JSON Objects from the given URL address
jsonobject = JSONfunctions.getJSONfromURL("http://cmx.org.mx/wp-content/uploads/json.txt");
if(jsonobject==null){
Intent intent = new Intent(MainActivity.this, CMX.class);
startActivity(intent);
finish();
}else{
try {
// Locate the array name in JSON
jsonarray = jsonobject.getJSONArray("posts");