Java 使用CustomListAdapter时出现NullPointerException
我在Android应用程序中创建CustomListAdapter。但是我在实现它时遇到了这个错误Java 使用CustomListAdapter时出现NullPointerException,java,android,nullpointerexception,listactivity,Java,Android,Nullpointerexception,Listactivity,我在Android应用程序中创建CustomListAdapter。但是我在实现它时遇到了这个错误NullPointerException 以下是我的CustomListAdapter.java代码: /** * */ package com.fanjavaid.searchhttprequest.adapter; import java.util.List; import com.android.volley.toolbox.ImageLoader; import com.andro
NullPointerException
以下是我的CustomListAdapter.java代码:
/**
*
*/
package com.fanjavaid.searchhttprequest.adapter;
import java.util.List;
import com.android.volley.toolbox.ImageLoader;
import com.android.volley.toolbox.NetworkImageView;
import com.fanjavaid.searchhttprequest.R;
import com.fanjavaid.searchhttprequest.app.AppController;
import com.fanjavaid.searchhttprequest.model.Menu;
import android.app.Activity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
/**
* @author fanjavaid
*
*/
public class CustomListAdapter extends BaseAdapter {
private Activity activity;
private LayoutInflater inflater;
private List<Menu> menuItems;
ImageLoader imageLoader = AppController.getInstance().getImageLoader();
public CustomListAdapter(Activity activity, List<Menu> menuItems) {
this.activity = activity;
this.menuItems = menuItems;
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return menuItems.size();
}
@Override
public Object getItem(int location) {
// TODO Auto-generated method stub
return menuItems.get(location);
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if (inflater == null)
inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if (convertView == null)
convertView = inflater.inflate(R.layout.list_row, null);
if (imageLoader == null)
imageLoader = AppController.getInstance().getImageLoader();
NetworkImageView thumbNail = (NetworkImageView) convertView.findViewById(R.id.thumbnail);
TextView menuTitle = (TextView) convertView.findViewById(R.id.menuTitle);
TextView inputDate = (TextView) convertView.findViewById(R.id.postDate);
// Getting movie data for the row
Menu m = menuItems.get(position);
// thumbnail image
thumbNail.setImageUrl(m.getThumbnailUrl(), imageLoader);
// title
menuTitle.setText(m.getMenuTitle());
// input date
inputDate.setText("Post Date : " + String.valueOf(m.getInputDate().toString()));
return convertView;
}
}
这是我的AppController.java
/**
*
*/
package com.fanjavaid.searchhttprequest.app;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.toolbox.ImageLoader;
import com.android.volley.toolbox.Volley;
import com.fanjavaid.searchhttprequest.util.LruBitmapCache;
import android.app.Application;
import android.text.TextUtils;
/**
* @author fanjavaid
*
*/
public class AppController extends Application {
public static final String TAG = AppController.class.getSimpleName();
private RequestQueue mRequestQueue;
private ImageLoader mImageLoader;
private static AppController mInstance;
@Override
public void onCreate() {
super.onCreate();
mInstance = this;
}
public static synchronized AppController getInstance() {
return mInstance;
}
public RequestQueue getRequestQueue() {
if (mRequestQueue == null) {
mRequestQueue = Volley.newRequestQueue(getApplicationContext());
}
return mRequestQueue;
}
public ImageLoader getImageLoader() {
getRequestQueue();
if (mImageLoader == null) {
mImageLoader = new ImageLoader(this.mRequestQueue,
new LruBitmapCache());
}
return this.mImageLoader;
}
public <T> void addToRequestQueue(Request<T> req, String tag) {
// set the default tag if tag is empty
req.setTag(TextUtils.isEmpty(tag) ? TAG : tag);
getRequestQueue().add(req);
}
public <T> void addToRequestQueue(Request<T> req) {
req.setTag(TAG);
getRequestQueue().add(req);
}
public void cancelPendingRequests(Object tag) {
if (mRequestQueue != null) {
mRequestQueue.cancelAll(tag);
}
}
}
/**
*
*/
包com.fanjavaid.searchhttprequest.app;
导入com.android.volley.Request;
导入com.android.volley.RequestQueue;
导入com.android.volley.toolbox.ImageLoader;
导入com.android.volley.toolbox.volley;
导入com.fanjavaid.searchhttprequest.util.LruBitmapCache;
导入android.app.Application;
导入android.text.TextUtils;
/**
*@author fanjavaid
*
*/
公共类AppController扩展应用程序{
公共静态最终字符串标记=AppController.class.getSimpleName();
私有请求队列mRequestQueue;
私有图像加载器;
专用静态应用控制器;
@凌驾
public void onCreate(){
super.onCreate();
mInstance=这个;
}
公共静态同步AppController getInstance(){
回报率;
}
公共请求队列getRequestQueue(){
if(mRequestQueue==null){
mRequestQueue=Volley.newRequestQueue(getApplicationContext());
}
返回mrequest队列;
}
公共ImageLoader getImageLoader(){
getRequestQueue();
if(mImageLoader==null){
mImageLoader=新的ImageLoader(this.mRequestQueue,
新的LruBitmapCache());
}
返回此.mImageLoader;
}
公共无效addToRequestQueue(请求请求,字符串标记){
//如果标记为空,则设置默认标记
请求setTag(TextUtils.isEmpty(tag)?tag:tag;
getRequestQueue().add(请求);
}
公共无效addToRequestQueue(请求请求){
要求设置标签(标签);
getRequestQueue().add(请求);
}
公共作废取消挂起请求(对象标记){
if(mRequestQueue!=null){
mRequestQueue.cancelAll(标记);
}
}
}
还有这个,我的MainActivity.java
package com.fanjavaid.searchhttprequest;
import java.util.LinkedList;
import java.util.List;
import org.apache.http.client.utils.URLEncodedUtils;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONArray;
import org.json.JSONObject;
import com.android.volley.Request.Method;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.VolleyLog;
import com.android.volley.toolbox.JsonArrayRequest;
import com.android.volley.toolbox.JsonObjectRequest;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends Activity {
private TextView responseText;
private EditText searchText;
private String url;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
responseText = (TextView) findViewById(R.id.textView1);
searchText = (EditText) findViewById(R.id.searchBox);
url = "http://tempercube.com/receip_finder/process_cari.php";
}
private String addLocationToUrl(String url, String parameter) {
if (!url.endsWith("?"))
url += "?";
List<BasicNameValuePair> params = new LinkedList<BasicNameValuePair>();
params.add(new BasicNameValuePair("bahan", parameter));
String paramString = URLEncodedUtils.format(params, "utf-8");
url += paramString;
return url;
}
public void doRequest(String passUrl) {
final ProgressDialog pDialog = new ProgressDialog(this);
pDialog.setMessage("Loading...");
pDialog.show();
JsonObjectRequest jsonObjRequest = new JsonObjectRequest(Method.GET, passUrl, null,
new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
// TODO Auto-generated method stub
Log.d("TAG", response.toString());
responseText.setText(response.toString());
Intent intent = new Intent("com.fanjavaid.searchhttprequest.ListMenuActivity");
Bundle extras = new Bundle();
extras.putString("json_menu", response.toString());
intent.putExtras(extras);
startActivity(intent);
pDialog.hide();
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
// TODO Auto-generated method stub
Log.d("ERROR", "Error : " + error.getMessage());
pDialog.hide();
}
});
// Make request queue
VolleySingleton.getInstance(getApplicationContext()).addToRequestQueue(jsonObjRequest);
}
public void searchMenu(View view) {
if(view.getId() == R.id.button1){
String paramSearch = searchText.getText().toString();
url = addLocationToUrl(url, paramSearch);
Log.d("URL_INFO", url);
doRequest(url);
// reset URL
url = "http://tempercube.com/receip_finder/process_cari.php";
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
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();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
package com.fanjavaid.searchhttprequest;
导入java.util.LinkedList;
导入java.util.List;
导入org.apache.http.client.utils.URLEncodedUtils;
导入org.apache.http.message.BasicNameValuePair;
导入org.json.JSONArray;
导入org.json.JSONObject;
导入com.android.volley.Request.Method;
导入com.android.volley.Response;
导入com.android.volley.VolleyError;
导入com.android.volley.VolleyLog;
导入com.android.volley.toolbox.JsonArrayRequest;
导入com.android.volley.toolbox.JsonObjectRequest;
导入android.app.Activity;
导入android.app.ProgressDialog;
导入android.content.Intent;
导入android.os.Bundle;
导入android.util.Log;
导入android.view.Menu;
导入android.view.MenuItem;
导入android.view.view;
导入android.widget.EditText;
导入android.widget.TextView;
公共类MainActivity扩展了活动{
私有文本视图响应文本;
私人编辑文本搜索文本;
私有字符串url;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
responseText=(TextView)findViewById(R.id.textView1);
searchText=(EditText)findViewById(R.id.searchBox);
url=”http://tempercube.com/receip_finder/process_cari.php";
}
私有字符串addLocationToUrl(字符串url,字符串参数){
如果(!url.endsWith(“?”)
url+=“?”;
List params=new LinkedList();
添加(新的BasicNameValuePair(“bahan”,参数));
String paramString=URLEncodedUtils.format(params,“utf-8”);
url+=paramString;
返回url;
}
公共void doRequest(字符串passUrl){
final ProgressDialog pDialog=新建ProgressDialog(本);
设置消息(“加载…”);
pDialog.show();
JsonObjectRequest JsonObjectRequest=新的JsonObjectRequest(Method.GET,passUrl,null,
新的Response.Listener(){
@凌驾
公共void onResponse(JSONObject响应){
//TODO自动生成的方法存根
Log.d(“TAG”,response.toString());
responseText.setText(response.toString());
Intent Intent=newintent(“com.fanjavaid.searchhttprequest.ListMenuActivity”);
Bundle extras=新Bundle();
putString(“json_菜单”,response.toString());
意图.临时演员(临时演员);
星触觉(意向);
pDialog.hide();
}
},
新的Response.ErrorListener(){
@凌驾
公共无效onErrorResponse(截击错误){
//TODO自动生成的方法存根
Log.d(“ERROR”,“ERROR:+ERROR.getMessage());
pDialog.hide();
}
});
//发出请求队列
getInstance(getApplicationContext()).addToRequestQueue(jsonObjRequest);
}
公共无效搜索菜单(视图){
if(view.getId()==R.id.button1){
String paramSearch=searchText.getText().toString();
url=addLocationToUrl(url,参数搜索);
Log.d(“URL_INFO”,URL);
doRequest(url);
//重置URL
url=”http://tempercube.com/receip_finder/process_cari.php";
}
}
@凌驾
公共布尔onCreateOptions菜单(菜单){
//为菜单充气;这会将项目添加到操作栏(如果存在)。
getMenuInflater().充气(R.menu.main,menu);
返回true;
}
@凌驾
公共布尔值onOptionsItemSelected(菜单项项){
//处理操作栏项目单击此处。操作栏将
//自动装置
/**
*
*/
package com.fanjavaid.searchhttprequest.app;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.toolbox.ImageLoader;
import com.android.volley.toolbox.Volley;
import com.fanjavaid.searchhttprequest.util.LruBitmapCache;
import android.app.Application;
import android.text.TextUtils;
/**
* @author fanjavaid
*
*/
public class AppController extends Application {
public static final String TAG = AppController.class.getSimpleName();
private RequestQueue mRequestQueue;
private ImageLoader mImageLoader;
private static AppController mInstance;
@Override
public void onCreate() {
super.onCreate();
mInstance = this;
}
public static synchronized AppController getInstance() {
return mInstance;
}
public RequestQueue getRequestQueue() {
if (mRequestQueue == null) {
mRequestQueue = Volley.newRequestQueue(getApplicationContext());
}
return mRequestQueue;
}
public ImageLoader getImageLoader() {
getRequestQueue();
if (mImageLoader == null) {
mImageLoader = new ImageLoader(this.mRequestQueue,
new LruBitmapCache());
}
return this.mImageLoader;
}
public <T> void addToRequestQueue(Request<T> req, String tag) {
// set the default tag if tag is empty
req.setTag(TextUtils.isEmpty(tag) ? TAG : tag);
getRequestQueue().add(req);
}
public <T> void addToRequestQueue(Request<T> req) {
req.setTag(TAG);
getRequestQueue().add(req);
}
public void cancelPendingRequests(Object tag) {
if (mRequestQueue != null) {
mRequestQueue.cancelAll(tag);
}
}
}
package com.fanjavaid.searchhttprequest;
import java.util.LinkedList;
import java.util.List;
import org.apache.http.client.utils.URLEncodedUtils;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONArray;
import org.json.JSONObject;
import com.android.volley.Request.Method;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.VolleyLog;
import com.android.volley.toolbox.JsonArrayRequest;
import com.android.volley.toolbox.JsonObjectRequest;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends Activity {
private TextView responseText;
private EditText searchText;
private String url;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
responseText = (TextView) findViewById(R.id.textView1);
searchText = (EditText) findViewById(R.id.searchBox);
url = "http://tempercube.com/receip_finder/process_cari.php";
}
private String addLocationToUrl(String url, String parameter) {
if (!url.endsWith("?"))
url += "?";
List<BasicNameValuePair> params = new LinkedList<BasicNameValuePair>();
params.add(new BasicNameValuePair("bahan", parameter));
String paramString = URLEncodedUtils.format(params, "utf-8");
url += paramString;
return url;
}
public void doRequest(String passUrl) {
final ProgressDialog pDialog = new ProgressDialog(this);
pDialog.setMessage("Loading...");
pDialog.show();
JsonObjectRequest jsonObjRequest = new JsonObjectRequest(Method.GET, passUrl, null,
new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
// TODO Auto-generated method stub
Log.d("TAG", response.toString());
responseText.setText(response.toString());
Intent intent = new Intent("com.fanjavaid.searchhttprequest.ListMenuActivity");
Bundle extras = new Bundle();
extras.putString("json_menu", response.toString());
intent.putExtras(extras);
startActivity(intent);
pDialog.hide();
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
// TODO Auto-generated method stub
Log.d("ERROR", "Error : " + error.getMessage());
pDialog.hide();
}
});
// Make request queue
VolleySingleton.getInstance(getApplicationContext()).addToRequestQueue(jsonObjRequest);
}
public void searchMenu(View view) {
if(view.getId() == R.id.button1){
String paramSearch = searchText.getText().toString();
url = addLocationToUrl(url, paramSearch);
Log.d("URL_INFO", url);
doRequest(url);
// reset URL
url = "http://tempercube.com/receip_finder/process_cari.php";
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
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();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
<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">
<ListView
android:id="@+id/list"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:divider="@color/list_divider"
android:dividerHeight="1dp"
android:listSelector="@drawable/list_row_selector">
</ListView>
</RelativeLayout>
listView = (ListView) findViewById(R.id.list);
adapter = new CustomListAdapter(this, menuList);
listView.setAdapter(adapter);
<application
android:name=".AppController" //this one
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme">
<application
android:name=".AppController" //this one
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme">