Develop Reference

i can't get Item Detail

I am learning android development and i have a problem displaying contact detail in my app.
When I click an item of contact activity, the app hangs.
Could you help me please?
This is the activity App of Contact List.
public class ListViewActivity3 extends AppCompatActivity {
ListView listView;
List<ContactHelper> listAdapter;
public static final String Key_Postion = "keyPosition" ;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list_view3);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
listAdapter = new ArrayList<ContactHelper>();
listAdapter.clear();
listAdapter.add(new ContactHelper("achref", "Tunisien", "2222222", R.drawable.imagesand));
listAdapter.add(new ContactHelper("achref", "Tunisien", "2222222", R.drawable.imagesand));
listAdapter.add(new ContactHelper("achref", "Tunisien", "2222222", R.drawable.imagesand));
listAdapter.add(new ContactHelper("achref", "Tunisien", "2222222", R.drawable.imagesand));
listAdapter.add(new ContactHelper("achref", "Tunisien", "2222222", R.drawable.imagesand));
listView = (ListView) findViewById(R.id.listviewCustomAdapter);
listView.setAdapter(new AdapterCustom(ListViewActivity3.this, R.layout.listviewitem1, listAdapter));
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Intent i3 = new Intent(ListViewActivity3.this, ContactDetailItem.class);
i3.putExtra(Key_Postion, position);
startActivity(i3);
}
});
}
}
and this the ConatctDetailItem
public class ContactDetailItem extends AppCompatActivity {
TextView n, ph, surn;
ImageView imgC;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_contact_detail_item);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
n = (TextView) findViewById(R.id.contactName);
surn = (TextView) findViewById(R.id.contactSurname);
ph = (TextView) findViewById(R.id.contactPhone);
imgC = (ImageView) findViewById(R.id.imgContact);
Bundle bundle = getIntent().getExtras();
if (bundle != null) {
ContactHelper contactHelper = new ContactHelper();
ListViewActivity3 lv = new ListViewActivity3();
int position = bundle.getInt(ListViewActivity3.Key_Postion);
n.setText(lv.listAdapter.get(position).getName());
surn.setText(lv.listAdapter.get(position).getSurname());
ph.setText(lv.listAdapter.get(position).getPhone());
imgC.setImageResource(lv.listAdapter.get(position).getPhoto());
}
}
}
Here is the logcat.
com.example.achre.activityapp E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.achre.activityapp/com.example.achre.activityapp.ContactDetailItem}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
at android.app.ActivityThread.access$600(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5041)
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:793)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.example.achre.activityapp.ContactDetailItem.onCreate(ContactDetailItem.java:50)
at android.app.Activity.performCreate(Activity.java:5104)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
at android.app.ActivityThread.access$600(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5041)
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:793)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
at dalvik.system.NativeStart.main(Native Method)

In ContactDetailItem you are creating new ListViewActivity3. Instead it put to extra ContactHelper object.
Change your code like this:
Intent i3 = new Intent(ListViewActivity3.this, ContactDetailItem.class);
i3.putExtra(Key_Postion, listAdapter.get(position));
startActivity(i3);
and in ContactDetailItem:
ContactHelper contactHelper = (ContactHelper) bundle.getSerializableExtra(ListViewActivity3.Key_Postion);
n.setText(contactHelper.getName());
// ...
also your ContactHelper class must implement Serializable interface

My simple "counter app" crashes when trying to move to another activity...why?

When trying to move to another activity the app crashes...
logcat
java.lang.RuntimeException: Unable to start activity ComponentInfo{myact.julianhernandez.com.counterapp/myact.julianhernandez.com.counterapp.CounterDisplay}: android.content.res.Resources$NotFoundException: String resource ID #0x0
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: android.content.res.Resources$NotFoundException: String resource ID #0x0
at android.content.res.Resources.getText(Resources.java:244)
at android.widget.TextView.setText(TextView.java:3888)
at myact.julianhernandez.com.counterapp.CounterDisplay.onCreate(CounterDisplay.java:31)
at android.app.Activity.performCreate(Activity.java:5231)
MainActivity.class Code
public class MainActivity extends AppCompatActivity {
Button moveActivity;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
moveActivity = (Button) findViewById(R.id.list1_button);
moveActivity.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent toCounter = new Intent(MainActivity.this , CounterDisplay.class);
startActivity(toCounter);
}
});
CounterDisplay.class Code
public class CounterDisplay extends AppCompatActivity {
private TextView countView;
private Button addButton;
private Button subtractButton;
//int initialCount = 0;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_counter_display);
countView = (TextView) findViewById(R.id.currentCount);
addButton = (Button) findViewById(R.id.add);
subtractButton = (Button) findViewById(R.id.subtract);
countView.setText(0);
//increment counter by 1
addButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
int currentCount;// = initialCount;
for(currentCount=0;currentCount>=0;currentCount++){
countView.setText(currentCount);
}
}
});
}
}
Why does this code crash when switching activities?

Textview.setText(int) method takes a resource ID, not the text you are trying to display. Because there are no resource strings matching the ID you pass in (which is 0 on line 31), an exception gets thrown.
There are additional overloads of the setText() method that allow you to pass in a char[] if you don't want to use resource strings. View the documentation for more information. http://developer.android.com/reference/android/widget/TextView.html

NoClassDefFoundError Exception when launching app in GenyMotion emulator

I wanted to test my code on another device than my physical one, so I launched the app in GenyMotion emulator with a Samsung Galaxy S3 (API 18), but it keeps throwing a NoClassDefFoundError Exception in my class "SlidingMenuUtil" (a customized drawer menu) which is called on startup by my MainActivity.
Here is code from my onCreate in MainActivity:
#Bind(R.id.viewContentFullScreen) RelativeLayout viewContentFullScreen;
#Bind(R.id.viewContentTopBar) RelativeLayout viewContentTopBar;
#Bind(R.id.topBarWrapper) RelativeLayout topbarView;
private ViewContainer viewContainer;
private SlidingMenuUtil leftMenu;
private Bundle bundle;
private MessageHandler messageHandler;
private GoBackFunction currentGoBackFunction;
private CallbackManager callbackManager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
bundle = savedInstanceState;
setContentView(R.layout.activity_main);
leftMenu = new SlidingMenuUtil(this, SlidingMenuUtil.MenuType.LEFT, R.layout.drawer_menu, (int)(LayoutUtil.getScreenWidth(this) * 0.75), false);
populateMenu();
ButterKnife.bind(this);
messageHandler = new MessageHandler(this, findViewById(R.id.spinner));
FacebookSdk.sdkInitialize(getApplicationContext());
callbackManager = CallbackManager.Factory.create();
}
The problem occurs in the SlidingMenuUtil class on line: 67. Here is the constructor for the class:
public SlidingMenuUtil(Activity activity, MenuType menuType, int menuLayout, int shownMenuWidth, boolean fadeEffectOn) {
this.activity = activity;
this.menuType = menuType;
this.shownMenuWidth = shownMenuWidth;
this.fadeEffectOn = fadeEffectOn;
this.screenWidth = LayoutUtil.getScreenWidth(activity);
this.rootView = (ViewGroup)((ViewGroup)activity.findViewById(android.R.id.content)).getChildAt(0);
this.activityWrapper = new RelativeLayout(activity);
this.activityWrapper.setLayoutParams(this.rootView.getLayoutParams());
this.overlay = new RelativeLayout(activity);
this.overlay.setLayoutParams(new ViewGroup.LayoutParams(-1, -1));
this.overlay.setBackgroundColor(Color.parseColor("#000000"));
this.overlay.setAlpha(0.0F);
this.overlay.setVisibility(View.GONE);
this.overlay.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
if (menuOpen) {
toggle(new ToggleMenu() {
#Override
public void animationDone() {
}
});
}
}
});
this.rootView.addView(this.overlay);
this.menu = (LinearLayout)activity.getLayoutInflater().inflate(menuLayout, (ViewGroup) null, false);
this.menu.setLayoutParams(new ViewGroup.LayoutParams(shownMenuWidth, -1));
if (menuType == MenuType.LEFT) {
this.menu.setTranslationX((float)(-shownMenuWidth));
} else {
this.menu.setTranslationX((float)(screenWidth));
}
this.rootView.addView(this.menu);
this.menuOpen = false;
}
lin 67 is:
this.overlay.setOnClickListener(new View.OnClickListener() {
As mentioned before the problem only occurs in the emulator.
Here is the log:
812-812/? E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.NoClassDefFoundError: nightout.dk.nightoutandroid.utils.SlidingMenuUtil$1
at nightout.dk.nightoutandroid.utils.SlidingMenuUtil.<init>(SlidingMenuUtil.java:67)
at nightout.dk.nightoutandroid.MainActivity.onCreate(MainActivity.java:40)
at android.app.Activity.performCreate(Activity.java:5133)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
at android.app.ActivityThread.access$600(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5103)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
I hope somone can help me out.
Any help will be gratly appreciated

Android CursorAdapter giving java.lang.NullPointerException error

I am having a few issues running my custom CursorAdapter in my application. According to my logcat, the error I get:
11-08 06:41:03.228 6109-6109/? W/System.err? java.lang.RuntimeException: Unable to start activity ComponentInfo{com.app.name/com.app.name.MyActivity}: java.lang.NullPointerException
11-08 06:41:03.229 6109-6109/? W/System.err? at com.app.name.MyActivity.onCreate(MyActivity.java:71)
11-08 06:41:03.231 6109-6109/? E/AndroidRuntime? FATAL EXCEPTION: main
occurs at line 71 which sets the adapter (obj.setAdapter(myAdapter)). Initially I thought my database data retrieve function (Cursor chatCursor = mydb.selectConversation(msgId);) did not return any data but after testing it with the chatCursor.getCount() function, I realized that was not the case. Kindly assist me in solving this issue. Below are the codes for my activity, adapter and logcat. Thanks in advance.
MyAdapter.java
public class MyAdapter extends CursorAdapter {
#TargetApi(Build.VERSION_CODES.HONEYCOMB)
public MyAdapter(Context context, Cursor cursor) {
super(context, cursor, 0);
}
#Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
return LayoutInflater.from(context).inflate(R.layout.chat_left, parent, false);
}
#Override
public void bindView(View view, Context context, Cursor cursor) {
TextView user = (TextView) view.findViewById(R.id.reply_user);
TextView msg = (TextView) view.findViewById(R.id.reply_msg);
String theTime = cursor.getString(cursor.getColumnIndexOrThrow("message_id"));
String theMessage = cursor.getString(cursor.getColumnIndexOrThrow("message"));
user.setText(theTime);
msg.setText(String.valueOf(theMessage));
}
}
MyActivity.java
public class MyActivity extends ListActivity {
//Utils Class
Utils util;
final Context context = this;
private ProgressBar dialog;
ListView obj;
DBHelper mydb;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_view);
util = new Utils(this);
mydb = new DBHelper(this);
Bundle extras = getIntent().getExtras();
final Integer msgId = extras.getInt("id");
obj = (ListView) findViewById(R.id.list);
Cursor chatCursor = mydb.selectConversation(msgId);
MyAdapter myAdapter = new MyAdapter(this, chatCursor);
obj.setAdapter(myAdapter);
}
}
logcat
11-08 06:41:03.228 6109-6109/? W/System.err? java.lang.RuntimeException: Unable to start activity ComponentInfo{com.app.name/com.app.name.MyActivity}: java.lang.NullPointerException
11-08 06:41:03.229 6109-6109/? W/System.err? at com.app.name.MyActivity.onCreate(MyActivity.java:71)
11-08 06:41:03.231 6109-6109/? E/AndroidRuntime? FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.app.name/com.app.name.MyActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2351)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2403)
at android.app.ActivityThread.access$600(ActivityThread.java:165)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1373)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:194)
at android.app.ActivityThread.main(ActivityThread.java:5370)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.app.name.MyActivity.onCreate(MyActivity.java:71)
at android.app.Activity.performCreate(Activity.java:5122)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1150)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2315)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2403)
at android.app.ActivityThread.access$600(ActivityThread.java:165)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1373)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:194)
at android.app.ActivityThread.main(ActivityThread.java:5370)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
at dalvik.system.NativeStart.main(Native Method)
11-08 06:41:03.238 559-832/? W/ActivityManager? Force finishing activity com.app.name/.MyActivity
11-08 06:41:03.742 559-574/? W/ActivityManager? Activity pause timeout for ActivityRecord{42e71938 u0 com.app.name/.MyActivity}

Take a look to your activity_view.xml. Probably the listview ID isn't "list" as you state when you try to find it with findViewById(R.layout.list).

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