java - Getting a "money converter" Android app to convert one currency to another based on user input -
so here instructions:
retrieve current currency conversion rates :
http://api.fixer.iofor example, convert dollars british pounds call:
http://api.fixer.io/latest?base=usd&symbols=gbp2- provide 2 spinners 5 currencies of choosing.
3 - use async calls conversion lookups, shouldn't block ui thread.
now i've gotten far pulling values json api , getting display conversion rate of 1 usd 1 gbp (this done hard coding in usd , gbp pull json api. i'm struggling trying hard coded currencies instead pulled pair of spinners containing 5 different currencies. additionally i'm struggling rate multiply user specified amount (for example if rate 0.69 , user wants convert 10usd gbp app should report converted amount 6.90gbp) @ present getting "operator * cannot applied double" @ present app crashes @ launch , first priority getting run , convert 1 monetary unit equivalent amount of monetary unit.
this fetchconversionratetask.java file
and android studio throwing error
package edu.ggc.tkeating.currencyconverter; import android.content.context; import android.media.mediaplayer; import android.os.asynctask; import android.util.log; import android.widget.edittext; import android.widget.textview; import org.json.jsonexception; import org.json.jsonobject; import java.io.bufferedinputstream; import java.io.ioexception; import java.net.httpurlconnection; import java.net.url; import java.text.decimalformat; import java.util.scanner; /** * created t3p0 on 6/9/2016. */ //http://api.fixer.io/latest?base=usd&symbols=gbp public class fetchconversionratetask extends asynctask<string, string, double> { private httpurlconnection conn; private textview tv; private context context; private edittext amount; private textview conversiontv; public fetchconversionratetask(context _context, textview _tv, edittext _amount){ this.tv = _tv; this.context = _context; this.amount = _amount; } private final static string tag = "currencyconverter"; @override protected void onpreexecute() { super.onpreexecute(); mediaplayer tingmp = mediaplayer.create(context, r.raw.ting); tingmp.start(); } @override protected double doinbackground(string... currencies){ string = currencies[0]; string = currencies[1]; double rate = 0.0d; double conversion = 0.0d; try{ url url = new url("http://api.fixer.io/latest?base="+ + "&symbols="+ to); conn = (httpurlconnection) url.openconnection(); scanner scanner = null; scanner = new scanner(new bufferedinputstream(conn.getinputstream())); string rslt =""; while (scanner.hasnext()) rslt += scanner.nextline(); log.i(tag, rslt); // {"base":"usd","date":"2016-06-09","rates":{"gbp":0.69151}} rate = new jsonobject(rslt).getjsonobject("rates").getdouble(to); conversion = new jsonobject(rslt).getjsonobject("conversion").getdouble(string.valueof(amount)); scanner.close(); return conversion; } catch (ioexception | jsonexception e){ e.printstacktrace(); } return rate; } @override protected void onpostexecute(double rate){ super.onpostexecute(rate); mediaplayer tingmp = mediaplayer.create(context, r.raw.ting); tingmp.start(); decimalformat format = new decimalformat("###.##"); string msg = "rate=" + format.format(rate); log.i(tag, msg); tv.settext(msg); } } this mainactivity.java
package edu.ggc.tkeating.currencyconverter; import android.os.bundle; import android.support.v7.app.appcompatactivity; import android.view.view; import android.widget.arrayadapter; import android.widget.button; import android.widget.edittext; import android.widget.spinner; import android.widget.textview; public class mainactivity extends appcompatactivity { private textview result; private edittext amount; private string fromcurr; private string tocurr; @override protected void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.activity_main); button button = (button) findviewbyid(r.id.btnconvert); result = (textview) findviewbyid(r.id.tvresult); amount = (edittext) findviewbyid(r.id.amount); spinner spinner2 = (spinner) findviewbyid(r.id.spinnerfrom); fromcurr = spinner2.getselecteditem().tostring(); spinner spinner = (spinner) findviewbyid(r.id.spinnerto); tocurr = spinner.getselecteditem().tostring(); // create arrayadapter using string array , default spinner layout arrayadapter<charsequence> adapter = arrayadapter.createfromresource(this, r.array.currency_array, android.r.layout.simple_spinner_item); // specify layout use when list of choices appears adapter.setdropdownviewresource(android.r.layout.simple_spinner_dropdown_item); // apply adapter spinner spinner.setadapter(adapter); button.setonclicklistener(new view.onclicklistener() { @override public void onclick(view v) { new fetchconversionratetask(getapplicationcontext(), result, amount).execute(fromcurr, tocurr); } }); } } activity_main.xml
<?xml version="1.0" encoding="utf-8"?> <android.support.design.widget.coordinatorlayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:fitssystemwindows="true" tools:context="edu.ggc.tkeating.currencyconverter.mainactivity"> <android.support.design.widget.appbarlayout android:layout_width="match_parent" android:layout_height="wrap_content" android:theme="@style/apptheme.appbaroverlay"> <android.support.v7.widget.toolbar android:id="@+id/toolbar" android:layout_width="match_parent" android:layout_height="?attr/actionbarsize" android:background="?attr/colorprimary" app:popuptheme="@style/apptheme.popupoverlay"/> </android.support.design.widget.appbarlayout> <include layout="@layout/content_main"/> </android.support.design.widget.coordinatorlayout> androidmanifest.xml
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="edu.ggc.tkeating.currencyconverter"> <uses-permission android:name="android.permission.internet"/> <application android:allowbackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:supportsrtl="true" android:theme="@style/apptheme"> <activity android:name=".mainactivity" android:label="@string/app_name" android:theme="@style/apptheme.noactionbar"> <intent-filter> <action android:name="android.intent.action.main"/> <category android:name="android.intent.category.launcher"/> </intent-filter> </activity> </application> </manifest> content_main.xml
<?xml version="1.0" encoding="utf-8"?> <relativelayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" app:layout_behavior="@string/appbar_scrolling_view_behavior" tools:context="edu.ggc.tkeating.currencyconverter.mainactivity" tools:showin="@layout/activity_main"> <button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="convert" android:id="@+id/btnconvert" android:layout_centervertical="true" android:layout_centerhorizontal="true"/> <textview android:layout_width="wrap_content" android:layout_height="wrap_content" android:textappearance="?android:attr/textappearancelarge" android:text="result" android:id="@+id/tvresult" android:layout_margintop="44dp" android:layout_below="@+id/btnconvert" android:layout_centerhorizontal="true" /> <edittext android:layout_width="wrap_content" android:layout_height="wrap_content" android:inputtype="numberdecimal" android:ems="10" android:id="@+id/amount" android:layout_above="@+id/btnconvert" android:layout_centerhorizontal="true" android:layout_marginbottom="79dp" android:hint="how want convert?"/> <spinner android:layout_width="match_parent" android:layout_height="wrap_content" android:id="@+id/spinnerto" android:spinnermode="dropdown" android:layout_above="@+id/btnconvert" android:layout_alignparentright="true" android:layout_alignparentend="true" android:layout_torightof="@+id/tvresult" android:layout_toendof="@+id/tvresult"/> <spinner android:layout_width="match_parent" android:layout_height="wrap_content" android:id="@+id/spinnerfrom" android:spinnermode="dropdown" android:layout_above="@+id/btnconvert" android:layout_toleftof="@+id/btnconvert" android:layout_tostartof="@+id/btnconvert"/> <textview android:layout_width="wrap_content" android:layout_height="wrap_content" android:textappearance="?android:attr/textappearancelarge" android:text="result" android:id="@+id/conversiontv" android:layout_margintop="22dp" android:layout_below="@+id/tvresult" android:layout_centerhorizontal="true"/> </relativelayout> i feel i'm missing incredibly simple , obvious , i'm hoping fresh eyes (and more experienced programmers) able figure code out. thank in advanced
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