Android :: Java - How To Check If Object Is Null
Jan 9, 2010
I am creating an application which retrieves images from the web. In case the image cannot be retrieved another local image should be used.
While trying to execute the following lines:
CODE:................
The line if(drawable.equals(null)) throws an exception if drawable is null.
Does anyone know how should the value of drawable be checked in order not to throw an exception in case it is null and retrieve the local image (execute drawable = getRandomDrawable())?
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Oct 29, 2012
I've gone through the Notepad Tutorials and they are all working on my virtual device. I am now stuck in the midst of trying to write my own Android app.
My setup:
Windows 7 SP 1 64-bit
Eclipse Indigo Service Release 2
Android Development Tools 16.0.1.v201112150204-238534
Android Virtual Device Platform 2.3.3, API Level 10, CPU/ABI ARM (armeabi)
The app is about as simple as they come - you enter a number, it divides it by another number and displays the result.Here is the code involved:
AndroidManifest.xml:
Code:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.android.driving"
android:versionCode="1"
android:versionName="1.0" >
[code]...
By the time DrivingTimeEstimator's onCreate() method gets executed, the Bundle object (savedInstanceState) is null (which I'm guessing is what leads to mMiles being null, which throws a NullPointerException and kills everything).
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Jun 22, 2009
I have a webview with a FriendConnect button to allow a user to login to FriendConnect.
When clicking on this button, I'm taken through the expected screens for logging in.
However, it seems like the last redirect after logging in fails with a Javascript error in the browser:
CODE:...............................
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Sep 3, 2010
I have a very simple Android activity layout like this:
CODE:..
Now when I (from onOptionsItemSelected) do the following:
CODE:...............
The contents of imgView is allways null!
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Aug 16, 2010
I am following the Parcelable example in the Android developer guide with the intention of having a more complex object that I send to different activities. Right now, my class is a wrapper of a String member. If I put the object in the intent and read it back from the Intent it reads as expected, however, on the receiver side, it is always null-pointer.
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Aug 8, 2010
I have an activity that implements LocationListener in my application and my onLocationChanged method has been working perfectly up until recently. For some reason the Location object being passed into the method is null. My question is, why is it null? Does it pass in a null object if it cannot acquire a location?
My GPS is on and I have it set to pull a location from the GPS, and I know my GPS can get a fix on me as I used Maps and had it locate me.
Also, I have the permission for my app set as:
CODE:.................
I don't believe permissions is the issue though, as my activity was working beforehand and I have not altered the permissions since then.
Here is the code that determines the provider of the location object:
CODE:.............
Here is the LogCat output of the error:
CODE:..............
I have tested the same code on another device (an HTC MyTouch 3G to be precise) and it works flawlessly with the GPS, however on my Motorola Droid it crashes.
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Feb 18, 2009
I am trying to get a FileInputStream object on an image that the user selects from the picture gallery.
This is the android URI returned by android.provider.MediaStore.Images.Media.INTERNAL_CONTENT_URI content://media/external/images/media/3
When I try to construct a java URI object from this object, I get an IllegalArgumentException with the exception description Expected file scheme in URI: content://media/external/images/media/3 whereas the android URI shows the scheme as content
Never found a solution for the original question. But if you want the byte stream of an image in the pictures gallery, this piece of code will do that.
CODE:...................
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Jun 25, 2010
I'm writing some stuff in java and i ran into some problems lately. cut short, i need to compare an object i created to another instance of this very class i instantiazed before with different data.
looks like this:
CODE:........
with a class a:
CODE:..........
The problem is, that i end up finding out that the values from newA are always equal to those from oldA. so i guess sth went wrong with passing the references of the objects in the last line of the loop...i thought java always passes references of objects unless an explicit copy() is called? if this does matter: this code is running on android - don't know if the dalvik vm messes aroung with this...
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Apr 14, 2009
I have constructed a Bitmap object in Java. Can you please tell me how can I scale it (x, y with a different ratio) on android?
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Jun 16, 2009
How can I get Pixel color of a coordinate? There is no method like canvas.getColor(x,y).
Actually, I am new to game developement. I am developing a Game which will restrict object if it comes to that boundary like in pac-man. How can I check that object has reached upto the boundary?
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Aug 31, 2009
I am using HttpURLConnection to send a GET request to a server. Upon reading the response code, the Android implementation of HttpURLConnection.doRequestInternal() throws an exception:
"java.io.IOException: Received authentication challenge is null"
I don't even get what the error is trying to tell me. I write an OAuth param string to the Authorization header, but this works fine on other occasions. There is nothing peculiar about my request apart from that.
Any idea what this means, what is causing this and how to get around it? This works fine with Sun's Java implementation, so I guess it's a problem with Apache Harmony?
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Nov 6, 2010
In my main activity, I have the following code that calls my FileBrowser activity: What's wrong? Can I not use putExtra with startActivityForResult? Can putExtra only be used with startActivity? Code...
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Dec 2, 2009
(Code is for Android Actually, I need code to be portable between Android and Java SE.)
I want to have a "settings" class with various game settings, like
public int map_size;
public String server_name;
etc.
The data needs to be accessed fairly frequently (so members, not a key-value map), and from time to time de/serialized in some standard way (mainly to send it through network).
I want to be able to
Serialize and deserialize the object into XML or JSON, without having to explicitly write the code for every member (but still having some degree of control over the format).
Define some (constant) meta-data about every member (default value, GUI name, XML identifier, ...), in a way that allows for easy modification in the source code (I want to be able to add a new meta-property, define a default value for it, and not have to specify it everywhere else).
1 is achievable by using reflection. I thought Java annotations for class members would be perfect for 2:
CODE:.............
But it looks like (user-defined) annotations don't work in Android yet - code using them crashes the compiler...
What would be the easiest way to store the meta-data about the settings (or another way to approach all this)?
Store information about settings in some external XML file? Store it in a Java data structure, with content defined in the code? Defining the data in this way somehow seems very unwieldy, especially compared to keyword arguments of annotations?
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Oct 29, 2010
From my android client i am sending a json to string object.but the .net client is getting it as empty string. here is my code...
is this header format correct?
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Jun 21, 2010
I have created a class with 3 sub classes in Java. The 3 sub classes contain variables to store information from my XML document. I am able to store in the first two for there are only single instances of the data in the XML. The third class contains variables that repeat multiple times. I want to store an object of "third class" objects. I also have a SAX parser class. I am doing this within an Android environment (1.6).
Does this make enough sense without displaying any code?
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Jul 28, 2010
I have 2 String Operations I would need relevant in Object C // Get the newstring from mystring start at counter Java: newstring = mystring.substring(counter) OBJ-C: ? // Get the position from searchstring in mystring Java: startpos = mystring.indexOf(searchstring) ObJ-C: ?
I had two other questions and found now the solution (here als for others)
CODE:.................................
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May 23, 2010
I was wondering what the simplest program for sending an object from my Android phone to my computer wirelessly (via LAN) would be. I have created Java RMI programs with a server and multiple clients, so I have a grasp of the concept. However with android I'm just not sure where to start.
What I am aiming to do is send some sort of information (could simply be text) to my computer and my computer will do an action. I have the GUI interface's and the actions to be carried out all worked out, just the sending of some sort of information is getting me.
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Sep 29, 2010
I thought when you passed objects to methods in Java, they were supposed to be by value.
public class MyClass{
int mRows;
int mCols;
Tile mTiles[][]; //Custom class
//Constructor
public MyClass(Tile[][] tiles, int rows, int cols) {..........
At this point, any changes to the mTiles object are reflected back to the tiles object.
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Apr 19, 2010
I'm building an android application, which has a list view, and in the list view, a click listener, containing an onItemClick method. So I have something like this:
public class myList extends ListActivity {
@Override
public void onCreate(Bundle savedInstanceState) {
getListView().setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
/* Do something*/
}
}
}
Normally, this works fine. However, many times I find myself needing too preform an application using the outer class as a context. thusfar, I've used: parent.getContext(); to do this, but I would like to know, is that a bad idea? I can't really call: because it's not really a subclass, just an embedded one. So is there any better way, or is that considered cosure? Also, if it is the right way, what should I do if the embedded method doesn't have a parameter to get the outside class?
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Mar 2, 2010
I'm writing an Android application. One problem is your app cannot contain a file whose uncompressed size is bigger than about 1Mb. I have a serialized object that I want to load that totals about 2Mb. My plan was to split this file into two smaller files, then load the object by combining both files at runtime.
However, I cannot work out how to use e.g. InputStream and ObjectInputStream to specify that I want to read the data from two input streams. How can I do this?
For example, say my object was split between file O1 and O2. How can I say "Load the object by reading the data from O1 then from O2"?
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Jun 22, 2010
So I ran into a problem today while working on my Android program. I have a class that turns that an XML string into a Java object (third party) and it works fine in as a regular java project but on Android I get this weird error:
CODE:.......
I hide my application name and my package for obvious reasons but I was wondering if anyone has ever encountered problems like this. Class is in the correct package, which is a library I have added. Other classes that I reference before are there and those can be made. Are there any other reasons a ClassNotFound Exception is thrown?
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Aug 25, 2010
In my Android client I want to receive JSON objects from a server. By googling I found a lot of different possibilities how to best parse the InputStream from the Server, but most of them wrote their own parser. Isn't there a library which does this parsing for me? Or how should I best implement it by myself?
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Aug 4, 2010
This should be simple, but I have tried if statements checking for null values and also ones checking the .length of it:
CODE:........
But it doesn't detect nothing was entered.
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Nov 19, 2010
I am facing a problem about encoding.
For example,
I have a message in xml format encoding is "UTF-8".
CODE:.........
Now, this message are supporting multiple language.
Traditional Chinese (big5), Simple Chinese (gb), English (utf-8)
And it will only change the encoding in specific fields.
For example (Traditional Chinese),
CODE:..........
Only "蘋果" and "橙" are using big5, "<product_name>" and "</product_name>" stills in use utf-8.
<price>1.3</price> and <price>1.2</price> are using utf-8.
How do I know which word is using different encoding?
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Jul 8, 2010
I'm doing Major Project on my final year and I'm very new to Android plus I;m not good at codings. I need help with my login page.
I've created something like a database connection java file which is this:
CODE:.......
I've already created a database for users using SQLite. The database name is Users and the table is called User. The records inside the table are Username, Password, LastName, FirstName. I've inserted one user's info into the database. The problem is I do not know whether my UserDB.java is correct.
And I've also created login.java. Hardcoded Login page:
CODE:.........
So I want to know how I should apply the database connection on the login.java. Should I insert database connection something like db.Open();? I studied ASP.Net a few months back and I kind of forget most of what I've learnt. So how should I open the database connection on login.java and how to check with database whether the user enters the right username and password?
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Sep 9, 2009
I want to do some automated testcase with Instrumentation . Suggest that my AUT has 2 Activity. After clicking the button in ther first Activity, the second one will be shown with new content base on what we enter in the first Activity.) Instrumentation provides us the function called startActivitySync() and return the Activity object for processing. My question is how we can get the pointer of the second Activity after the it is shown by clicking the button on the first activity.?
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Jun 8, 2009
I would like to convert a Picture object to Bitmap object in memory, without writing data to disk.
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Sep 21, 2009
I have an Activity that running on system. I can get the Intent that is used to start the activity. But i don't know how to get the Activity object from the Intent object or something else. Can anyone tell me how to do this??? Note that, I don't use Instrumentation object.
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May 21, 2009
I've got the following row xml file which consists of CheckboxView and TextView;
CODE:............
When the app run, i'm unable to "tick" any of the check boxes...
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Sep 2, 2010
Check for system updates doesn't check.
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