This question already has answers here:
How can I fix 'android.os.NetworkOnMainThreadException'? (64 answers)
Closed 7 years ago.
Im getting null pointer exception. This error seems a pretty usual one, but all the answers I found on the site were specific to a problem in others code which unfortunately I cant relate to in my code.
I'm a novice to android programming. Please help figure out the problem in this program. Here's the code.
Little bit of background on what Im trying to do. I'm just getting the http response from the google finance web service & set the http response to the textView component in the UI
package com.android.myexchange;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
public class MyExchangeActivity extends Activity {
private Spinner spinner1, spinner2;
private Button btnSubmit;
private EditText textbox;
private TextView result;
private TextView test;
private static final String TAG = "MyApp";
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
spinner1 = (Spinner) findViewById(R.id.SpinnerA);
spinner2 = (Spinner) findViewById(R.id.SpinnerB);
btnSubmit = (Button) findViewById(R.id.btnSubmit);
textbox = (EditText) findViewById(R.id.textbox);
result = (TextView) findViewById(R.id.resulttext);
textbox.setText("Enter amount");
String testStr=HTTPRequestPoster.sendGetRequest("
http://www.google.com/finance/converter", "a=1&from=USD&to=INR");
Log.i(TAG, "TEST");
result.setText(testStr);
addListenerOnButton();
}
private void addListenerOnButton() {
btnSubmit.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Toast.makeText(MyExchangeActivity.this,
"OnClickListener : " +
"\nSpinner 1 : "+ String.valueOf(spinner1.getSelectedItem()) +
"\nSpinner 2 : "+ String.valueOf(spinner2.getSelectedItem()),
Toast.LENGTH_SHORT).show();
}
});
}
}
Here's the manifest xml:
<uses-sdk android:minSdkVersion="14" />
<uses-permission android:name="android.permission.INTERNET"/>
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
<activity
android:label="@string/app_name"
android:name=".MyExchangeActivity" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
Here's the log:
12-19 21:47:42.403: W/System.err(647): android.os.NetworkOnMainThreadException
12-19 21:47:42.403: W/System.err(647): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1084)
12-19 21:47:42.413: W/System.err(647): at java.net.InetAddress.lookupHostByName(InetAddress.java:391)
12-19 21:47:42.413: W/System.err(647): at java.net.InetAddress.getAllByNameImpl(InetAddress.java:242)
12-19 21:47:42.413: W/System.err(647): at java.net.InetAddress.getAllByName(InetAddress.java:220)
12-19 21:47:42.413: W/System.err(647): at libcore.net.http.HttpConnection.<init>(HttpConnection.java:71)
12-19 21:47:42.413: W/System.err(647): at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50)
12-19 21:47:42.423: W/System.err(647): at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:351)
12-19 21:47:42.423: W/System.err(647): at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:86)
12-19 21:47:42.423: W/System.err(647): at libcore.net.http.HttpConnection.connect(HttpConnection.java:128)
12-19 21:47:42.423: W/System.err(647): at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:308)
12-19 21:47:42.433: W/System.err(647): at libcore.net.http.HttpEngine.connect(HttpEngine.java:303)
12-19 21:47:42.433: W/System.err(647): at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:282)
12-19 21:47:42.433: W/System.err(647): at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:232)
12-19 21:47:42.433: W/System.err(647): at libcore.net.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:273)
12-19 21:47:42.433: W/System.err(647): at libcore.net.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:168)
12-19 21:47:42.433: W/System.err(647): at com.android.myexchange.HTTPRequestPoster.sendGetRequest(HTTPRequestPoster.java:43)
12-19 21:47:42.443: W/System.err(647): at com.android.myexchange.MyExchangeActivity.onCreate(MyExchangeActivity.java:37)
12-19 21:47:42.443: W/System.err(647): at android.app.Activity.performCreate(Activity.java:4465)
12-19 21:47:42.443: W/System.err(647): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
12-19 21:47:42.453: W/System.err(647): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919)
12-19 21:47:42.463: W/System.err(647): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980)
12-19 21:47:42.473: W/System.err(647): at android.app.ActivityThread.access$600(ActivityThread.java:122)
12-19 21:47:42.473: W/System.err(647): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146)
12-19 21:47:42.473: W/System.err(647): at android.os.Handler.dispatchMessage(Handler.java:99)
12-19 21:47:42.504: W/System.err(647): at android.os.Looper.loop(Looper.java:137)
12-19 21:47:42.504: W/System.err(647): at android.app.ActivityThread.main(ActivityThread.java:4340)
12-19 21:47:42.504: W/System.err(647): at java.lang.reflect.Method.invokeNative(Native Method)
12-19 21:47:42.513: W/System.err(647): at java.lang.reflect.Method.invoke(Method.java:511)
12-19 21:47:42.513: W/System.err(647): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
12-19 21:47:42.513: W/System.err(647): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
12-19 21:47:42.513: W/System.err(647): at dalvik.system.NativeStart.main(Native Method)
12-19 21:47:42.513: I/MyApp(647): TEST
12-19 21:47:42.523: D/AndroidRuntime(647): Shutting down VM
12-19 21:47:42.523: W/dalvikvm(647): threadid=1: thread exiting with uncaught exception (group=0x409951f8)
12-19 21:47:42.543: E/AndroidRuntime(647): FATAL EXCEPTION: main
12-19 21:47:42.543: E/AndroidRuntime(647): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.android.myexchange/com.android.myexchange.MyExchangeActivity}: java.lang.NullPointerException
12-19 21:47:42.543: E/AndroidRuntime(647): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955)
12-19 21:47:42.543: E/AndroidRuntime(647): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980)
12-19 21:47:42.543: E/AndroidRuntime(647): at android.app.ActivityThread.access$600(ActivityThread.java:122)
12-19 21:47:42.543: E/AndroidRuntime(647): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146)
12-19 21:47:42.543: E/AndroidRuntime(647): at android.os.Handler.dispatchMessage(Handler.java:99)
12-19 21:47:42.543: E/AndroidRuntime(647): at android.os.Looper.loop(Looper.java:137)
12-19 21:47:42.543: E/AndroidRuntime(647): at android.app.ActivityThread.main(ActivityThread.java:4340)
12-19 21:47:42.543: E/AndroidRuntime(647): at java.lang.reflect.Method.invokeNative(Native Method)
12-19 21:47:42.543: E/AndroidRuntime(647): at java.lang.reflect.Method.invoke(Method.java:511)
12-19 21:47:42.543: E/AndroidRuntime(647): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
12-19 21:47:42.543: E/AndroidRuntime(647): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
12-19 21:47:42.543: E/AndroidRuntime(647): at dalvik.system.NativeStart.main(Native Method)
12-19 21:47:42.543: E/AndroidRuntime(647): Caused by: java.lang.NullPointerException
12-19 21:47:42.543: E/AndroidRuntime(647): at com.android.myexchange.MyExchangeActivity.onCreate(MyExchangeActivity.java:39)
12-19 21:47:42.543: E/AndroidRuntime(647): at android.app.Activity.performCreate(Activity.java:4465)
12-19 21:47:42.543: E/AndroidRuntime(647): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
12-19 21:47:42.543: E/AndroidRuntime(647): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919)
12-19 21:47:42.543: E/AndroidRuntime(647): ... 11 more
Here's the layout xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="
http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="@drawable/plain_white_paper"
android:orientation="vertical" >
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal" >
<Spinner
android:id="@+id/SpinnerA"
android:layout_width="150dp"
android:layout_height="43dp"
android:layout_margin="10dp"
android:background="#8e99a4"
android:dropDownWidth="150dp"
android:entries="@array/currency"
android:textColor="@android:color/black" />
<EditText
android:id="@+id/textbox"
android:layout_width="135dp"
android:layout_height="38dp"
android:background="#8e99a4"
android:cursorVisible="true"
android:gravity="center_horizontal"
android:inputType="number"
android:text="@string/hello" >
<requestFocus />
</EditText>
</LinearLayout>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal" >
<Spinner
android:id="@+id/SpinnerB"
android:layout_width="150dp"
android:layout_height="50dp"
android:layout_margin="10dp"
android:background="#8e99a4"
android:dropDownWidth="150dp"
android:entries="@array/currency" />
<TextView
android:id="@+id/resulttext"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:layout_weight="0.68"
android:background="#8e99a4"
android:padding="25px"
android:text="@string/hello" />
</LinearLayout>
<Button
android:id="@+id/btnSubmit"
android:layout_width="128dp"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_margin="10dp"
android:text="Submit"
android:textColor="#181f25" />
<TextView
android:id="@+id/textView1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="0.93"
android:text="TextView" />
</LinearLayout>
The exception occurs right after the log entry where I try to setText the http response text to TextView UI component. As far as I know the exception is occurring because result.setText(testStr) is having a porblem which I dont understand. The class HTTPRequestPost.java works perfectly fine. Ive tested it & it returns the httpresponse in string format. I can post code of HTTPRequestPost.java if you need it.
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