It is necessary to send several requests for volleyball - in sequence

Question

I need to use a volley to send a request for membership, and then pass this member ID to the second volleyball request to get statistics for this member.

I have a problem with my first request that works fine, but the second request seems to start before the variable is returned for transmission. Does anyone know how to prevent the second query from starting before returning a value?

Answer 1

you cannot just write each request sequentially and wait to execute each after each response to success ... you need to call the second request inside the first response of the service ... i.e.

public void firstServiceCall(String url) { JsonObjectRequest jsonObjReq = new JsonObjectRequest( Request.Method.GET, url, null, new Response.Listener<JSONObject>() { @Override public void onResponse(JSONObject response) { int membershipid=response.getInt("membershipid"); //suppose the membershipid comes under main json with key "membershipid" secondServiceCall(membershipid,<url2>); // on the response of first service ... call to the second service ... and continue so on... if required } }, new Response.ErrorListener() { @Override public void onErrorResponse(VolleyError error) { } }); Volley.newRequestQueue(getApplicationContext()).add(jsonObjReq); } public void secondServiceCall(int membershipid,String url) { // use this var membershipid acc to your need ... JsonObjectRequest jsonObjReq = new JsonObjectRequest( Request.Method.GET, url, null, new Response.Listener<JSONObject>() { @Override public void onResponse(JSONObject response) { } }, new Response.ErrorListener() { @Override public void onErrorResponse(VolleyError error) { } }); Volley.newRequestQueue(getApplicationContext()).add(jsonObjReq); } 

the request is also asynchronous, therefore ... another process will not wait for the service call to complete ... therefore, the second service starts before the first response of the service

Answer 2

Code for connecting asynchronous Volley requests. What's important:
a) Call nextRequest () in the mJsonResp listener.
nextRequest () binds each link in the chain together and is called by the listener.
b) Member of mLinkedRequest.
c) An abstract function that needs to be redefined by getRequest ().
d) How to create ("use") HTTP requests for registration:

 // 1) POST registrations -> 2) PATCH registrations -> 3) GET devices pkRequest ChainReg3 = new LinkedRequest(pkURL.devices, null ) { @Override public JSONObject getRequest( final JSONObject response ){ JSONObject retVal = new JSONObject(); retVal.put( "MyAwesomeString", "This is the final request string in the chain" ); return retVal; } } ; pkRequest ChainReg2 = new LinkedRequest(pkURL.registrations2, ChainReg3 ){ //pkRequest ChainReg2 = new pkRequest(pkURL.registrations2, null ){ @Override public JSONObject getRequest( final JSONObject response ){ JSONObject retVal = new JSONObject(); retVal.put( "MyAwesomeInt", 99 ); return retVal; }; JSONObject firstRequestBodyTest = new JSONObject( "test" ); pkRequest ChainReg1 = new LinkedRequest(pkURL.registrations, firstRequestBodyTest , ChainReg2 ){ @Override public JSONObject getRequest( final JSONObject response ){ return null; } }; ChainReg1.submit(); } 

/ * FYI: I created an enumeration to work with all URLs. You can deal with them in some other way. The point of this post is to show how to combine asynchronous volleyball requests.

 package org.Somepackage; import android.support.annotation.NonNull; import android.widget.Toast; import com.android.volley.*; import com.android.volley.Request.*; import com.android.volley.Response.ErrorListener; import com.android.volley.toolbox.JsonObjectRequest; import org.json.*; import org.peacekeeper.util.pkUtility; import java.net.*; import java.util.*; public abstract class LinkedRequest{ protected static org.slf4j.Logger mLog; protected final static pkUtility mUtility = pkUtility.getInstance(); protected final static RequestQueue mRequestQueue = mUtility.getRequestQueue(); protected final static Toast mToast = Toast.makeText( mUtility.getBaseContext(), "", Toast.LENGTH_LONG ); static private HashMap< String, String > newHeader(){ HashMap< String, String > newHeader = new HashMap<>(); final String applicationjson = "application/json"; newHeader.put( "Accept", applicationjson ); newHeader.put( "Content-Type", applicationjson ); return newHeader; } static private HashMap<String, String> mHeaders = newHeader() , registrations2Hdr = newHeader(); static{ // http://stackoverflow.com/questions/19797842/patch-request-android-volley registrations2Hdr.put( "X-HTTP-Method-Override", "PATCH" ); } //end static private UUID msg_id = UUID.randomUUID(); //each enum needs priority and method, url, request, response, errlsnr protected final Response.Listener< JSONObject > mJsonResp = new Response.Listener< JSONObject >(){ @Override public void onResponse( JSONObject response ){ String respStr = "response:\t" + ((response == null)? "NULL" : response.toString() ); mToast.setText( respStr ); mToast.show(); mLog.debug( "onResponse\t url:\t" + mPkURL.toString() + "\t:Response:\t" + respStr ); nextRequest( response ); } }; protected final ErrorListener mErrLsnr = new ErrorListener(){ @Override public void onErrorResponse( VolleyError error ){ mToast.setText( "Error:\t" + error.getMessage() ); mToast.show(); mLog.error( "Error!:\t" + error.getMessage() ); if( error.networkResponse != null){ NetworkResponse response = error.networkResponse; int statusCode = error.networkResponse.statusCode; mLog.error( "statuscode:\t" + statusCode + ":\t" + new String(response.data) ); } } }; private HashMap< String, String > getAuthorizationHeader(){ HashMap< String, String > newHeader = newHeader(); //newHeader.put( "Authorization", SecurityGuard.getAuthToken() ); newHeader.put( "Authorization", "test getAuthToken()" ); mLog.debug( newHeader.toString() ); return newHeader; } //PLACE ALL URL NAMES HERE public enum pkURL{ //each link in the chain should be of ever increasing priority to reflect its progression. devices(Method.GET, Priority.IMMEDIATE) // http://stackoverflow.com/questions/28314160/error-in-volley-patch // java.net.ProtocolException: Unknown method 'PATCH'; must be one of [OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE] // http://stackoverflow.com/questions/19797842/patch-request-android-volley , registrations2( Method.POST, Priority.HIGH, LinkedRequest.registrations2Hdr) , registrations(Method.POST, Priority.NORMAL ) , status ; //each enum needs priority and method, url, request, response, errlsnr protected Priority mPriority; protected int mMethod; public HashMap< String, String > mHeader; protected String URLstr; pkURL(){ mMethod = Method.GET; mPriority = Priority.LOW; mHeader = LinkedRequest.mHeaders; } pkURL(int aMethod, Priority aPriority ){ mMethod = aMethod; mPriority = aPriority; mHeader = LinkedRequest.mHeaders; } pkURL(int aMethod, Priority aPriority, HashMap< String, String > aHeader){ this(aMethod, aPriority); mHeader = aHeader; } }//enum pkURL public pkURL mPkURL; private JsonObjectRequest mJsonRequest = null;//The current request of this link. For future Request override getRequest(). private LinkedRequest mLinkedRequest = null; //This constructor is only used for intermediate and last links in the chain. public LinkedRequest( @NonNull pkURL aPkURL, LinkedRequest aLinkedRequest ){ mLog = org.slf4j.LoggerFactory.getLogger( getClass() ); mPkURL = aPkURL; if ( aLinkedRequest != null ){ mLinkedRequest = aLinkedRequest; mLinkedRequest.msg_id = this.msg_id; } }//cstr //This constructor is only used for the first link in the chain or singleton requests. public LinkedRequest( @NonNull final pkURL aPkURL, @NonNull JSONObject aRequestBody, LinkedRequest aLinkedRequest ){ this( aPkURL, aLinkedRequest ); try{ aRequestBody.put( "_id", msg_id.toString() ); } catch ( Exception ignore ){} mJsonRequest = //this is the current request of this link. For future Requests override getRequest(). new JsonObjectRequest( aPkURL.mMethod, toURL(), aRequestBody, mJsonResp, mErrLsnr ){ @Override public Priority getPriority() { return mPkURL.mPriority; } @Override public Map<String, String> getHeaders() throws AuthFailureError{ return aPkURL.mHeader; } }; mJsonRequest.setShouldCache( false ); }//cstr private static final String URLhead = "http://192.168.1.156/"; private String toURL(){ //} throws JSONException{ //private < E extends Enum< E > > URL toURL( E URLPostOrGet ){ URL url; switch ( mPkURL){ case registrations2: this.mPkURL.URLstr = "registrations/" + this.msg_id; this.mPkURL.mHeader = registrations2Hdr; break; case devices: final String deviceID = "testdeviceId" //SecurityGuard.getEntry( entryType.deviceId ) , keeperID = "testkeeperId" //SecurityGuard.getEntry( entryType.keeperId ) ; //GET http://192.168.1.156:80/devices/bbdef07b-9360-4d7b-8448-21c4daca4711?where=keeperId=="b0c486e5-13b1-4555-ba5f-d54bb1f0a6f7" this.mPkURL.URLstr = new StringBuilder( "devices/" ) .append( deviceID ) .append( "?where=keeperId==\"" ) .append( keeperID + "\"" ) .toString(); this.mHeaders = getAuthorizationHeader(); break; default: this.mPkURL.URLstr = mPkURL.name(); }//switch try{ url = new URL(URLhead + this.mPkURL.URLstr + "/" ); } catch ( MalformedURLException e ){ mLog.error( "Error!:\t" + e.getMessage() ); url = null; } return url.toString(); }//toURL @Override public String toString(){ String toURL = toURL(); if (mJsonRequest == null) return "toString() NULL mJsonRequest:\t" + toURL; String hdrs; try{ hdrs = this.mJsonRequest.getHeaders().toString(); } catch ( AuthFailureError aAuthFailureError ){ hdrs = "ERROR: getHeaders()"; } return new StringBuilder( "\nmethod:\t:" + mJsonRequest.getMethod() ) .append( "\nheaders:\t" + hdrs ) .append( "\nbody:\t" + new String( mJsonRequest.getBody()) ) .append( "\nBodyContentType:\t" + mJsonRequest.getBodyContentType() ) .append( "\nPriority:\t" + mJsonRequest.getPriority() ) .append( "\ngetUrl():\t" + mJsonRequest.getUrl() ) .append( "\ntoURL():\t" + toURL ) .append( "\n" ) .toString(); }//toString() //getRequest is used for the FUTURE request of mLinkedRequest. //for CURRENT request of this() use the constructor abstract public JSONObject getRequest( final JSONObject response ); private Request nextRequest(final JSONObject aResponse ){//nextRequest() ties each link in the chain together and is called by the listener. mLog.debug( "nextRequest:\t" + aResponse.toString() ); Request retVal = null; // * * * * * * This is how and where the the "future" request must be called/constructed. * * * * * * if ( mLinkedRequest != null ){ final int mMethod = mLinkedRequest.mPkURL.mMethod; final String aURL = mLinkedRequest.toURL(); final JSONObject requestBody = mLinkedRequest.getRequest( aResponse ); final Priority priority = mLinkedRequest.mPkURL.mPriority; final Map<String, String> header = mLinkedRequest.mPkURL.mHeader; this.mJsonRequest = new JsonObjectRequest( mMethod, aURL, requestBody, mJsonResp, mErrLsnr ){ @Override public Priority getPriority() { return priority; } @Override public Map<String, String> getHeaders() throws AuthFailureError{ return header; } }; mJsonRequest.setShouldCache( false ); this.mLinkedRequest = mLinkedRequest.mLinkedRequest; retVal = submit(); }//if // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * return retVal; }//nextRequest() public Request submit(){ mLog.debug( "submit:\n" ); mLog.debug( this.toString() ); if ( mLinkedRequest != null ) mLog.debug( "mLinkedRequest:\t" + mLinkedRequest.toString() ); if ( mJsonRequest!= null ) return mRequestQueue.add( mJsonRequest ); return null; }//submit() }//class LinkedRequest