Trying to receive data from the Facebook Graph API, but I seem to be getting a NullPointerException. Can someone please help? Here is my activity file with the xml and logCat output.
package com.example.fbtest;
// Omitted all import statements.
public class TestActivity extends Activity implements OnClickListener {
String APP_ID;
Facebook fb;
private SharedPreferences sp;
TextView tv;
ImageView login;
Button b;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_test);
APP_ID = getString(R.string.APP_ID);
fb = new Facebook(APP_ID);
sp = getPreferences(MODE_PRIVATE);
String access_token = sp.getString("access_token", null);
long expires = sp.getLong("access_expires", 0);
if (access_token != null) {
fb.setAccessToken(access_token);
}
if (expires != 0) {
fb.setAccessExpires(expires);
}
login = (ImageView) findViewById(R.id.login);
login.setOnClickListener(this);
b=(Button)findViewById(R.id.button1);
b.setOnClickListener(this);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_test, menu);
return true;
}
private void post() {
if (fb.isSessionValid()) {
login.setImageResource(R.drawable.logout_button);
JSONObject obj;
try {
obj = Util.parseJson(fb.request("ronakshah"));
String id = obj.optString("id");
String name = obj.optString("name");
tv.setText("Welcome, " + name + id);
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
} catch (FacebookError fe) {
} catch (IOException e) {
e.printStackTrace();
}
}
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
switch (v.getId()) {
case R.id.login:
if (fb.isSessionValid()) {
// button close our session - log out of facebook
try {
fb.logout(getApplicationContext());
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} else {
// login to facebook
fb.authorize(TestActivity.this, new String[] { "email",
"read_stream" }, new DialogListener() {
public void onFacebookError(FacebookError e) {
// TODO Auto-generated method stub
Toast.makeText(TestActivity.this, "fbError",
Toast.LENGTH_SHORT).show();
}
public void onError(DialogError e) {
// TODO Auto-generated method stub
Toast.makeText(TestActivity.this, "onError",
Toast.LENGTH_SHORT).show();
}
public void onComplete(Bundle values) {
// TODO Auto-generated method stub
Editor editor = sp.edit();
editor.putString("access_token", fb.getAccessToken());
editor.putLong("access_expires", fb.getAccessExpires());
editor.commit();
}
public void onCancel() {
// TODO Auto-generated method stub
Toast.makeText(TestActivity.this, "onCancel",
Toast.LENGTH_SHORT).show();
}
});
}
case R.id.button1:
post();
}
}
}
<LinearLayout 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"
android:orientation="vertical"
>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="@dimen/padding_medium"
android:text="@string/hello_world"
tools:context=".TestActivity" />
<ImageView
android:id="@+id/login"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/login_button"
android:text="Button" />
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button" />
LogCat :
07-18 14:10:42.636: I/dalvikvm(385): Jit: resizing JitTable from 512 to 1024
07-18 14:10:47.216: D/dalvikvm(385): GC_CONCURRENT freed 555K, 52% free 2998K/6151K, external 908K/1038K, paused 9ms+8ms
07-18 14:13:39.126: D/dalvikvm(385): GC_CONCURRENT freed 492K, 52% free 2988K/6151K, external 918K/1038K, paused 9ms+9ms
07-18 14:13:39.235: D/webviewglue(385): nativeDestroy view: 0x270d38
07-18 14:13:40.525: D/dalvikvm(385): GC_CONCURRENT freed 554K, 54% free 2867K/6151K, external 726K/1038K, paused 14ms+10ms
07-18 14:13:41.395: D/AndroidRuntime(385): Shutting down VM
07-18 14:13:41.395: W/dalvikvm(385): threadid=1: thread exiting with uncaught exception (group=0x40015560)
07-18 14:13:41.416: E/AndroidRuntime(385): FATAL EXCEPTION: main
07-18 14:13:41.416: E/AndroidRuntime(385): java.lang.NullPointerException
07-18 14:13:41.416: E/AndroidRuntime(385): at com.example.fbtest.TestActivity.post(TestActivity.java:73)
07-18 14:13:41.416: E/AndroidRuntime(385): at com.example.fbtest.TestActivity.onClick(TestActivity.java:136)
07-18 14:13:41.416: E/AndroidRuntime(385): at android.view.View.performClick(View.java:2485)
07-18 14:13:41.416: E/AndroidRuntime(385): at android.view.View$PerformClick.run(View.java:9080)
07-18 14:13:41.416: E/AndroidRuntime(385): at android.os.Handler.handleCallback(Handler.java:587)
07-18 14:13:41.416: E/AndroidRuntime(385): at android.os.Handler.dispatchMessage(Handler.java:92)
07-18 14:13:41.416: E/AndroidRuntime(385): at android.os.Looper.loop(Looper.java:123)
07-18 14:13:41.416: E/AndroidRuntime(385): at android.app.ActivityThread.main(ActivityThread.java:3683)
07-18 14:13:41.416: E/AndroidRuntime(385): at java.lang.reflect.Method.invokeNative(Native Method)
07-18 14:13:41.416: E/AndroidRuntime(385): at java.lang.reflect.Method.invoke(Method.java:507)
07-18 14:13:41.416: E/AndroidRuntime(385): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
07-18 14:13:41.416: E/AndroidRuntime(385): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
07-18 14:13:41.416: E/AndroidRuntime(385): at dalvik.system.NativeStart.main(Native Method)
Thanks in advance!
You are never assigning anything to your tv variable.
Assuming you want to reference the TextView in your XML file, you have to give it an id:
android:id="@+id/welcomeText"
and then assign it to your tv variable:
tv = (TextView) findViewById(R.id.welcomeText);