Java singleton类的requestQueue返回空值
截击库不会从博客中获取帖子。我是这方面的初学者,我被卡住了,我真的需要完成这项工作。我不知道错误是从哪里来的 这是MainActivity.java:Java singleton类的requestQueue返回空值,java,android,json,android-volley,Java,Android,Json,Android Volley,截击库不会从博客中获取帖子。我是这方面的初学者,我被卡住了,我真的需要完成这项工作。我不知道错误是从哪里来的 这是MainActivity.java: public void onResponse(JSONObject response) { try { JSONObject feedResponse = response.getJSONObject("feed"); JSONArray entryArrayPosts = fee
public void onResponse(JSONObject response) {
try {
JSONObject feedResponse = response.getJSONObject("feed");
JSONArray entryArrayPosts = feedResponse.getJSONArray("entry");
BlogPost bp;
for (int i = 0; i < entryArrayPosts.length(); i++){
bp = new BlogPost();
//Get the entry as an array and loop through
JSONObject entryBlogPost = entryArrayPosts.getJSONObject(i);
//Get the title from the array
JSONObject postObject = entryBlogPost.getJSONObject("title");
//JSONObject postHtmlContent = entryBlogPost.getJSONObject(KEYS.POST_JSON_OBJECT_HTML_CONTENT);
//GET LINK ARRAY FROM JSON
JSONArray linkAddress = entryBlogPost.getJSONArray(KEYS.POST_JSON_ARRAY_OBJECT);
if(entryBlogPost.has(KEYS.MEDIA_THUMBNAIL)) {
JSONObject imageObjectUrl = entryBlogPost.getJSONObject(KEYS.MEDIA_THUMBNAIL);
String thumbnailUrl = imageObjectUrl.getString(KEYS.MEDIA_THUMBNAIL_URL);
bp.setmUrlThumbnail(thumbnailUrl);
}
//for loop for link array object
for (int j = 0;j < linkAddress.length(); j++){
JSONObject eachLink = linkAddress.getJSONObject(4);
String htmlUrl = eachLink.getString(KEYS.POST_HTML_LINK);
bp.setmLinkContent(htmlUrl);
}
//Get title string contained in Title Object
String title = postObject.getString(KEYS.POST_TITLE);
Log.v(TAG, "OBJECTS HAVE THIS PROPERTIES: " + i + " " + title);
//Set Properties Gotten
bp.setmTitle(title);
Log.v(TAG, "OBJECTS HAVE THIS PROPERTIES: " + i + " " + bp.toString());
//Add a blog post Object to the Arraylist
postArrayList.add(bp);
}
// Log.v(TAG, "Arraylist SIZE " + postArrayList.size());
for(BlogPost posts : postArrayList){
Log.v(TAG, posts + " ");
}
// Toast.makeText(this.,response.toString(),Toast.LENGTH_LONG).show();
}catch(JSONException e){
Log.v(TAG, e.toString());
}
}
},new Response.ErrorListener(){
@Override
public void onErrorResponse(VolleyError error) {
Log.v(TAG, error.toString());
}
});
RequestSingleton.getInstance(this).addToRequestQueue(jsonRequest);
}
实际错误:java.lang.RuntimeException:无法启动活动组件信息{wait.com.linasblog/wait.com.linasblog.MainActivity}:java.lang.NullPointerException:尝试调用虚拟方法'android.content.Context android.Context.getApplicationContext()'在空对象引用上Post All call stack.java.lang.RuntimeException:无法启动活动组件信息{wait.com.linasblog/wait.com.linasblog.MainActivity}:java.lang.NullPointerException:尝试调用虚拟方法'android.content.Context android.content.Context.getApplicationContext()'在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)的android.app.ActivityThread.handleLaunchActivity的空对象引用上(ActivityThread.javaI尝试添加堆栈跟踪您的问题,但它看起来是错误的。您可以添加您的问题并添加完整的跟踪吗?wait.com.linasblog.MainActivity上应该有几行提到
。实际错误:java.lang.RuntimeException:无法启动activity ComponentInfo{wait.com.linasblog/wait.com.linasblog.MainActivity}:java.lang.NullPointerException:尝试对空对象引用调用虚拟方法“android.content.Context android.Context.getApplicationContext()”,Post整个调用堆栈。java.lang.RuntimeException:无法启动活动组件信息{wait.com.linasblog/wait.com.linasblog.MainActivity}:java.lang.NullPointerException:尝试在android.app.ActivityThread.performLaunchActivity上的空对象引用上调用虚拟方法“android.content.Context.getApplicationContext()”(ActivityThread.java:2416)位于android.app.ActivityThread.handleLaunchActivity(ActivityThread.javaI尝试添加stacktrace跟踪您的问题,但它看起来是错误的。您可以添加您的问题并添加完整的跟踪吗?wait.com.linasblog.MainActivity上应该有几行提到。
public class RequestSingleton {
private static RequestSingleton mInstance ;
private RequestQueue mRequestQueue;
private ImageLoader mImageLoader;
private static Context mCtx;
private RequestSingleton(Context context){
mCtx = context;
mRequestQueue = getRequestQueue();
mImageLoader = new ImageLoader(mRequestQueue, new ImageLoader.ImageCache(){
private final LruCache<String, Bitmap> cache = new LruCache<String, Bitmap>(20);
@Override
public Bitmap getBitmap(String url) {
return cache.get(url);
}
@Override
public void putBitmap(String url, Bitmap bitmap) {
cache.put(url, bitmap);
}
});
}
public static synchronized RequestSingleton getInstance(Context context){
if (mInstance == null){
mInstance = new RequestSingleton(context);
}
return mInstance;
}
private RequestQueue getRequestQueue(){
if(mRequestQueue == null){
mRequestQueue = Volley.newRequestQueue(mCtx.getApplicationContext());
}
return mRequestQueue;
}
public <T> void addToRequestQueue(Request<T> req){
getRequestQueue().add(req);
}
public ImageLoader getImageLoader(){
return mImageLoader;
}
}
java.lang.RuntimeException: Unable to start activity ComponentInfo{wait.com.linasblog/wait.com.linasblog.MainActivity}:
java.lang.NullPointerException: Attempt to invoke virtual method
'android.content.Context android.content.Context.getApplicationContext()'
on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java...