-3
MainActivity.javaJSON數據不從網絡解析
import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.widget.ListView;
import android.widget.Toast;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.IOException;
import java.util.ArrayList;
public class MainActivity extends Activity {
ListView list;
ActorsAdapter adapter;
ArrayList<Actors> actorslist;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
list = (ListView)findViewById(R.id.list);
adapter = new ActorsAdapter(getApplicationContext(), R.layout.list_category, actorslist);
list.setAdapter(adapter);
actorslist=new ArrayList<Actors>();
new actorsAsyncTask().execute("http://paradiseitsolutions.co.in/app/sanvi/json/getcategory.php");
}
public class actorsAsyncTask extends AsyncTask<String,Void,Boolean>{
@Override
protected Boolean doInBackground(String... params) {
try {
HttpClient client= new DefaultHttpClient();
HttpPost post=new HttpPost(params[0]);
HttpResponse response= client.execute(post);
int status =response.getStatusLine().getStatusCode();
if(status==200){
HttpEntity entity=response.getEntity();
String data= EntityUtils.toString(entity);
JSONObject jobj= new JSONObject(data);
JSONArray jarray = jobj.getJSONArray("result");
for(int i =0;i<jarray.length();i++){
Actors actor = new Actors();
JSONObject jrealObject = jarray.getJSONObject(i);
actor.setId(jrealObject.getString("id"));
actor.setName(jrealObject.getString("name"));
actor.setImage(jrealObject.getString("image"));
actorslist.add(actor);
}
return true;
}
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
return false;
}
@Override
protected void onPostExecute(Boolean result) {
super.onPostExecute(result);
if(result== false)
{
//data is not parse
Toast.makeText(getApplicationContext(), "this is my Toast message!!! =)",
Toast.LENGTH_LONG).show();
}else {
ActorsAdapter adapter =new ActorsAdapter(getApplicationContext(),R.layout.list_category,actorslist);
list.setAdapter(adapter);
}
}
}
}
ActorsAdapter.java
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import java.io.InputStream;
import java.util.ArrayList;
/**
* Created by paradise on 2/27/2016.
*/
public class ActorsAdapter extends ArrayAdapter<Actors> {
ArrayList<Actors> ArrayListActors;
int Resource;
Context context;
LayoutInflater vi;
public ActorsAdapter(Context context, int resource, ArrayList<Actors> objects) {
super(context, resource, objects);
ArrayListActors =objects;
Resource=resource;
this.context = context;
vi=(LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if(convertView == null){
convertView = vi.inflate(Resource,null);
holder = new ViewHolder();
holder.ivImage = (ImageView)convertView.findViewById(R.id.ivImage);
holder.tvId = (TextView)convertView.findViewById(R.id.tvId);
holder.tvName = (TextView)convertView.findViewById(R.id.tvName);
convertView.setTag(holder);
}else {
holder = (ViewHolder)convertView.getTag();
}
new DownloadImageTask(holder.ivImage).execute();
holder.tvId.setText("id =" + ArrayListActors.get(position).getId());
holder.tvName.setText("name=" +ArrayListActors.get(position).getName());
return convertView;
}
static class ViewHolder {
public TextView tvId;
public ImageView ivImage;
public TextView tvName;
}
private class DownloadImageTask extends AsyncTask<String, Void, Bitmap> {
ImageView bmImage;
public DownloadImageTask(ImageView bmImage) {
this.bmImage = bmImage;
}
protected Bitmap doInBackground(String... urls) {
String urldisplay = urls[0];
Bitmap mIcon = null;
try {
InputStream in = new java.net.URL(urldisplay).openStream();
mIcon = BitmapFactory.decodeStream(in);
} catch (Exception e) {
Log.e("Error", e.getMessage());
e.printStackTrace();
}
return mIcon;
}
}
}
Actors.java
public class Actors {
private String id;
private String name;
private String image;
//getters and setters
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getImage() {
return image;
}
public void setImage(String image) {
this.image = image;
}
//default constructor
public Actors(){
}
}
activity_main.xml中
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="5dp"
tools:context="com.example.paradise.pagalshayar.MainActivity">
<ListView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/list"
tools:listitem="@layout/list_category">
</ListView>
</RelativeLayout>
list_category.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:text="id"
android:id="@+id/tvId"/>
<ImageView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/ivImage"/>
<TextView
android:text="name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/tvName"/>
</LinearLayout>
在我的應用程序3級和2級的XML文件。但問題是，JSON是不解析應用程序已經墜毀，戈夫錯誤消息Fatel異常：主要
錯誤消息
02-27 13:57:16.197 19624-19624/com.example.paradise.pagalshayar E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.paradise.pagalshayar, PID: 19624
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.paradise.pagalshayar/com.example.paradise.pagalshayar.MainActivity}: java.lang.NullPointerException: Attempt to invoke interface method 'int java.util.List.size()' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'int java.util.List.size()' on a null object reference
at android.widget.ArrayAdapter.getCount(ArrayAdapter.java:337)
at android.widget.ListView.setAdapter(ListView.java:491)
at com.example.paradise.pagalshayar.MainActivity.onCreate(MainActivity.java:40)
at android.app.Activity.performCreate(Activity.java:6251)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
'顯示java.lang.NullPointerException ：''參考這個答案http://stackoverflow.com/questions/218384/what-is-a-null-pointer-exception-and-how-do-i-fix-it – ELITE