Develop Reference

Application not working on Android Kitkat

I'm creating my own application. I tested it on Android Lollipop and Marshmallow - everything works great. But whenever I try Android Kitkat, an error occurs. Here's error log:
E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.newproject/com.example.newproject.Progi}: java.lang.ClassCastException: java.lang.Object[] cannot be cast to java.math.BigDecimal[][]
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
at android.app.ActivityThread.access$600(ActivityThread.java:130)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4745)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.ClassCastException: java.lang.Object[] cannot be cast to java.math.BigDecimal[][]
at com.example.newproject.Progi.onCreate(Progi.java:62)
at android.app.Activity.performCreate(Activity.java:5008)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084) 
at android.app.ActivityThread.access$600(ActivityThread.java:130) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195) 
at android.os.Handler.dispatchMessage(Handler.java:99) 
at android.os.Looper.loop(Looper.java:137) 
at android.app.ActivityThread.main(ActivityThread.java:4745) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:511) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
at dalvik.system.NativeStart.main(Native Method) 
It looks like problem is on line 62 in "progi" class, but - as for me - everything is OK especially that on newer Android versions it works great.
public class Progi extends AppCompatActivity {
Intent intent;
Bundle liczby;
Bundle doble;
BigDecimal tablica [][];
BigDecimal punkty = new BigDecimal(-1);
#Override
public boolean onPrepareOptionsMenu(Menu menu)
{
android.content.SharedPreferences shared = android.preference.PreferenceManager.getDefaultSharedPreferences(this);
boolean warunek = shared.getBoolean("serial", false);
android.view.MenuItem menuitem = menu.getItem(0);
if(warunek)
{
menuitem.setTitle("Oceny pojedynczo");
}
else menuitem.setTitle("Oceny seryjnie");
return true;
}
public boolean onCreateOptionsMenu(Menu menu) {
android.view.MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.firstmenu, menu);
return true;
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.layoutprogi);
Toolbar myToolbar = (Toolbar) findViewById(R.id.my_toolbar);
setSupportActionBar(myToolbar);
getSupportActionBar().setTitle("Progi punktowe");
intent = getIntent();
liczby = intent.getBundleExtra("liczby");
doble = intent.getBundleExtra("doble");
tablica = (BigDecimal[][]) doble.getSerializable("doble"); //here is line 62
if(intent.hasExtra("max")) {
Bundle a = intent.getBundleExtra("max");
punkty = (BigDecimal) a.getSerializable("max");
}
przejscie(true);
if(punkty.compareTo(new BigDecimal(-3))==0)
{
procenty(findViewById(android.R.id.content));
}
else if(punkty.compareTo(new BigDecimal(-1))!=0)
{
liczymy(findViewById(android.R.id.content));
}}
And in case someone asking "what 'tablica' gets from intent?":
BigDecimal[][] tablica = new BigDecimal[16][3];
//here i get data from file and put in inside "tablica"
Bundle doble = new Bundle();
doble.putSerializable("doble", tablica);
Intent intent = new Intent(Starter.this, MyActivity.class);
intent.putExtra("doble", doble);
startActivity(intent);
Any idea what's wrong?

Try switching your array implementation (BigDecimal[] []) to ArrayList.
If you want to pass an Array through an intent on Android versions
prior to Android 5.0.1 (maybe some older versions work aswell, but up
to Android 4.3 it is NOT working) You'll have to work around it. You
could do this by converting your Array to an ArrayList.
Then you would be casting it something like this:
(ArrayList<ArrayList<BigDecimal>>) doble.getSerializable("doble");
Related SO answer

Setting OnClickListener throws an exception?

I want to know why my application is throwing a runtime exception when I run it? I used to the code in the following link for my application,
dynamically add and remove view to viewpager.
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ActionBar ab=getActionBar();
pagerAdapter = new MainPagerAdapter();
pager = (ViewPager) findViewById (R.id.pager);
pager.setAdapter (pagerAdapter);
inflater = (LayoutInflater)getSystemService
(Context.LAYOUT_INFLATER_SERVICE);
v0 = (FrameLayout) inflater.inflate (R.layout.listlayout, null);
Button button=(Button)findViewById(R.id.button1);
button.setOnClickListener(this);
pagerAdapter.addView (v0, 0);
pagerAdapter.notifyDataSetChanged();
}
#Override
public void onClick(View v) {
if(v.getId()==R.id.button1)
{
pagerAdapter.addView (v0);
pagerAdapter.notifyDataSetChanged();
}
}
LogCat:
FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.todolistworkable/com.example.todolistworkable.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1970)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1995)
at android.app.ActivityThread.access$600(ActivityThread.java:128)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1161)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4514)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:790)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:557)
at dalvik.system.NativeStart.main(Native Method)Caused by: java.lang.NullPointerException
at com.example.todolistworkable.MainActivity.onCreate(MainActivity.java:43)
at android.app.Activity.performCreate(Activity.java:4465)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1053)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1934)

the object on line 43 of your code within your onCreate method is null. Most likely the target of one of your findViewById calls is not returning what you expect it to.
See this for more info.
How to interpret Logcat

android.os.NetworkOnMainThreadException [duplicate]

This question already has answers here:
How can I fix 'android.os.NetworkOnMainThreadException'?
(66 answers)
Closed 8 years ago.
I make simply rss reader in android. I have the errors (I searched and tried some solutions but nothing):
Couldn't open http://pogoda.wp.pl/rss.xml
java.io.IOException: Couldn't open http://pogoda.wp.pl/rss.xml
at org.apache.harmony.xml.ExpatParser.openUrl(ExpatParser.java:755)
at org.apache.harmony.xml.ExpatReader.parse(ExpatReader.java:292)
at javax.xml.parsers.SAXParser.parse(SAXParser.java:390)
at javax.xml.parsers.SAXParser.parse(SAXParser.java:266)
at com.newsreader.RssReader.getItems(RssReader.java:23)
at com.newsreader.MainActivity$1$1.run(MainActivity.java:48)
at android.os.Handler.handleCallback(Handler.java:605)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4340)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
at dalvik.system.NativeStart.main(Native Method)
Caused by: android.os.NetworkOnMainThreadException
at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1084)
at java.net.InetAddress.lookupHostByName(InetAddress.java:391)
at java.net.InetAddress.getAllByNameImpl(InetAddress.java:242)
at java.net.InetAddress.getAllByName(InetAddress.java:220)
at libcore.net.http.HttpConnection.<init>(HttpConnection.java:71)
at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50)
at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:351)
at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:86)
at libcore.net.http.HttpConnection.connect(HttpConnection.java:128)
at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:308)
at libcore.net.http.HttpEngine.connect(HttpEngine.java:303)
at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:282)
at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:232)
at libcore.net.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:273)
at libcore.net.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:168)
at org.apache.harmony.xml.ExpatParser.openUrl(ExpatParser.java:753)
and activity:
public class MainActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
new Thread(){
public void run(){
MainActivity.this.runOnUiThread(new Runnable(){
#Override
public void run() {
try{
RssReader reader = new RssReader("http://pogoda.wp.pl/rss.xml");
ListView items = (ListView) findViewById(R.id.listView1);
ArrayAdapter<RssItem> adapter = new ArrayAdapter<RssItem>(MainActivity.this, android.R.layout.simple_list_item_1, reader.getItems());
items.setAdapter(adapter);
Log.i("", ""+reader);
items.setOnItemClickListener(new ListListener(reader.getItems(), MainActivity.this));
}catch(Exception e){
Log.e("blad", e.getMessage(), e);
}
}
});
}
}.start();
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}
I don't know what am I doing wrong. Maybe someone has got the same problem so please help.
Thanks

It is because you are performing network operation on main thread of activity. Using Async task will be a better option.

Caused by: android.os.NetworkOnMainThreadException
This speaks for itself.
Don't do networking on the main Thread!
AsyncTask to the rescue. Try it out it will work.

Always use AsyncTask to solve this issue.
BUT, if you're within the movie Swordfish, someone points a gun at you and say "fix it in 30 seconds", then change your targetSdkVersion to 9 in the Android Manifest and the exception will stop. Don't worry, it will run on devices with version higher than 9 too. Even so, correct your code later using AsyncTask.

Android takepicture failed at Android version 4.1.1 but succeed in version 4.0.0

I got the LogCat :
java.lang.RuntimeException: takePicture failed
at android.hardware.Camera.native_takePicture(Native Method)
at android.hardware.Camera.takePicture(Camera.java:1061)
at android.hardware.Camera.takePicture(Camera.java:1006)
at com.cidtech.portraitcatch.service.MyService.takePic(MyService.java:168)
at com.cidtech.portraitcatch.service.MyService$1.onClick(MyService.java:78)
at android.view.View.performClick(View.java:4088)
at android.view.View$PerformClick.run(View.java:16984)
at android.os.Handler.handleCallback(Handler.java:615)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4745)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
the curial code is below:
public void takePic(){
home_takePic.setEnabled(false);
camera = Camera.open();
if(bitmapList == null){
bitmapList = new ArrayList<Bitmap>();
}
for(int i=0; i<5; i++){
camera.takePicture(null, null, new MyPictureCallback());
SystemClock.sleep(1000);
}
saveBitmapToSdcard();
releaseResource();
home_takePic.setEnabled(true);
}
I also do this:
public void takePic(){
home_takePic.setEnabled(false);
camera = Camera.open();
***camera.startPreview();***
if(bitmapList == null){
bitmapList = new ArrayList<Bitmap>();
}
for(int i=0; i<5; i++){
camera.takePicture(null, null, new MyPictureCallback());
SystemClock.sleep(1000);
}
// saveBitmapToSdcard();
releaseResource();
home_takePic.setEnabled(true);
}
but still get the same Exception
the method camera.takePicture have been performed in version 4.0.4 but faild in version 4.1.1, who can tell me how to solve it ,please help me ,thanks

You need to be making a call to startPreview() before you attempt the call to takePicture(). Do this after you call Camera.open().
As per Android documentation:
Important: Call startPreview() to start updating the preview surface.
Preview must be started before you can take a picture.
startPreview documentation

Simple SharedPreferences in Android

I'm having a problem, and I already tried everything I found on this site, it's not helping, so I'm asking this question myself.
my code is:
public class MyActivity extends Activity{
protected PositionSense positionSense;
protected Preferences preferences;
String IP;
String ID;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
positionSense = new PositionSense(this, null);
SharedPreferences settings = getSharedPreferences("preferences", 0);
IP = settings.getString("ip", "http://192.168.1.3:8080/servlet");
ID = settings.getString("id", "USER");
}
Later on, I use these variables in a background running thread that contacts the servlet and sends some info (including position and ID of the user which is saved in preferences)
I'm not posting all of that because I don't want to clog up the thread more than necessary (but if it is needed, I will post it all)
In any case, it doesn't work and it gives me the following error log:
09-14 16:47:20.854: WARN/dalvikvm(552): threadid=1: thread exiting with uncaught exception (group=0x409c01f8)
09-14 16:47:20.884: ERROR/AndroidRuntime(552): FATAL EXCEPTION: main
java.lang.IllegalStateException: Could not execute method of the activity
at android.view.View$1.onClick(View.java:3044)
at android.view.View.performClick(View.java:3511)
at android.view.View$PerformClick.run(View.java:14105)
at android.os.Handler.handleCallback(Handler.java:605)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4424)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at android.view.View$1.onClick(View.java:3039)
... 11 more
Caused by: java.lang.NullPointerException
at com.moodswings.MoodSwingsActivity.clickHappy(MoodSwingsActivity.java:94)
... 14 more
I don't know what to do about it.
Can someone give me the SIMPLEST possible way to save 2 strings in preferences in one activity that are used in some other activity within the same application? It's supposed to be really simple, but I simply cannot make it work, and I'm nearing my deadline.
Thanks!

To save to shared preferences you can try:
String ip = "192.168.1.1";
SharedPreferences prefs = getSharedPreferences("IP", Context.MODE_PRIVATE);
prefs.edit().putString("Sample IP", ip).commit();
To get the information from the shared preferences you can try:
String newIP = prefs.getString("Sample IP");//You can also place a default value if needed; to bypass the null character.
Now to pass them into activities you can try doing an intent call like below
**Activity One
Intent intent = new Intent(getApplicationContext(),SecondActivity.class);
intent.putExtra("IP",newIp);
startActivity(intent);
**Activity Two
Bundle extras = intent.getExtras();
String tmp = extras.getString("IP");
Also you can use this link to reference.