Develop Reference

the returnValue of my Stringbuilder is not loeded into the String I want to send as an extra, why?

I have a function getConfiguration(char type). depending on a selected option, a certain character like 'A' or 'M'or sent to getConfiguration(char type). my getconfiguration builds a long string and depending on the type one part of will be executed:
getConfiguration(char type){
String allConfig = "";
allConfig += "BEGIN\n";
if (type=='A'||type=='M'){
....
}
if (type=='A'||type=='X'){
...
}
allConfig += "ENDE";
return allConfig;
}
A is the complete list and everything works well for A but for all other options although I get dataConfig: //parameters are correctly changed
for the string in which I want to save it this whole part of the function is not executed. and I get for:
String result=dataConfig.getConfig(...)
result =" BEGIN\nEND
any ideas what is happening?

let's say class A costructs the class Config that includes the getConfig() and then sends the answer to class B. for that it uses:
putExtra("tagForValue",Value);
when the string is modified in class B the answer should be also sent back using the same putExtra
my problem was I was sending it back again. but still not getting any errors, because I had used the same "tagForValue" so often it was using another Extra.
I hope this helps some other beginner like me!

Is it possible to see which functions are called in Logcat?

I know, there is a way to see which functions are called in log-cat is to write a log message on top for every function like this
#Override
protected void onDestroy() {
super.onDestroy();
Log.d("myTag","onDestroy function is called!");
// some logic
}
But it becomes irritating when you have more function.
So, I wonder if there is a way to see which functions are called in adb-logcat without writing log messages for every function.
I hope they can be fetched from somewhere in the stack but I couldn't find it.

You can try Hugo. In that case you have to annotate your methods with #DebugLog only. Then Hugo will generate logs for you (and will print out arguments and return value!). Example from GitHub:
#DebugLog
public String getName(String first, String last) {
SystemClock.sleep(15); // Don't ever really do this!
return first + " " + last;
}
And log output:
V/Example: ⇢ getName(first="Jake", last="Wharton")
V/Example: ⇠ getName [16ms] = "Jake Wharton"

Instead of printing log in every function. I (or most of the people) would suggest you to put debug.
To use debug first create breakpoints inside every function you want to check. To apply breakpoints simply left click in the area to the left of your code (refer image the pink circle represents a break-point).
Then to use Debug you have to press this button after successfully running your application.
As soon as the first method is called your application will pause at the break-point, then you can use F8 (or F6 if you are using eclipse settings) to move to next line, to move to next break-point you can press F9(or F8 if you are using eclipse settings). this way to can check all the functions being called.
This break-point method is really helpful if you just want to make sure that a particular function is being called.
Other than this if you still insist to know the details of all the functions you can store the stacktrace.
final StackTraceElement[] trace = new Throwable().getStackTrace())
StackTraceElement STrace = trace[1];
String className = STrace.getMethodName();

Android: why use intent.putExtra() method?

This is a real noob question I'm sure, but I am finding it quite perplexing.
Why an earth would you want to ever use intent.putExtra method to share information between classes in Android?
Let me explain. I am making my first Android app following the instructions from the developers guide (I am already at a moderate level with Java) and I am using some code that looks like this:
//Class field
//key holds string????? not fully understanding this...
public static final String EXTRA_MESSAGE = "self.anon.myfirstapp.MESSAGE";
//this method is activated by a button being pressed
public void sendMessage(View view) {
Intent intent = new Intent(this,DisplayMessageActivity.class);
EditText editText = (EditText) findViewById(R.id.edit_message);
String message = editText.getText().toString();
//puts string message inside the string EXTRA_MESSAGE - why????
intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
}
OK firstly I want to point out I see what is happening and for the most part how it works (am just confused by the field declaration = "myClassPath" why?)...
BUT....
Surely it would be easier just to have a static field called:
public static String message;
then my method would look like this:
public void sendMessage(View view) {
Intent intent = new Intent(this,DisplayMessageActivity.class);
EditText editText = (EditText) findViewById(R.id.edit_message);
message = editText.getText().toString();
startActivity(intent);
}
Then when my class DisplayMessageActivity needs the string message he just calls for:
String message = myClass.message;
That seems so much more straight forward. What is with the creation of the new string EXTRA_MESSAGE which just seems to hold the string message and why send it with the intent when my other class can access this info directly anyway -- and what does the field declaration with the "self.anon.myfirstapp.MESSAGE" mean? I can find no such folder or path leading to anything.

As someone else stated there are often situations (such as a screen rotate) in which the android system destroys and restarts the app - so all variable data is lost. It would only work consistently the way you suggest if your data is hard coded as a final variable. That is not the only reason for using intents though.
The great thing with using an intent to pass information is that you can use the intent not just to communicate with sub-activities within your own application but to any activity installed on that android system. For example you may want to launch an intent which starts the phone application and include as an extra the number that you want to call.
Perhaps a better question than yours though is "why would you not use intents to pass information?" The intent.putExtra() method allows you a convenient flexible and straight forward method to pass as much information as you like in a safe and secure way to any other activity.

intent.putExtra(EXTRA_MESSAGE, message);
works like a key value pair, when you want to retrieve the information from the intent you can simply do intent.get<type>Extra and get said information, in this case, intent.getStringExtra("self.redway.myfirstapp.MESSAGE'). its simply the key to retrieve the information, it does not have to be your entire classpath.
it could just as easily be intent.putExtra("message",message).
They are helpful when passing information that you don't necessarily want to reveal to another class but you do want it to be able to get that information in another manner from what i have found.

message = myClass.message It is not always certain that this will retain its value especially when it extends Android framework classes like Activity. When your activity is recreated(change of screen orientation) then message can lose its current value and be assigned a default value. myClass.message would work if message was a static field or else you would need to provide getter and setter methods for object of the Activity Class. Well creating objects of activity class is unheard of in my experience.

Measure time for rendering ListView

How can I measure time that ListView/ListActivity takes for rendering its list?
I have a ListActivity that takes a long time to show (on older devices it's ~3s) and I'd like to optimize that.
EDIT:
I already have time between Activity1 and Activity2. During this time, Activity2 is doing some stuff (initializing). Among other things, it renders its list. I want to get time this activity takes to render that list. If total time between activities is 3s, I want to know whether rendering list takes 2.9s or 0.5s....

You could simply ouput the time. For example you could use the logcat
final long t0 = System.currentTimeMillis();
// code to measure
Log.w(TAG, "TEXT" + System.currentTimeMillis()-t0);
Of course you could use any other system for the ouput like a dialog or stuff. Just use what you like.
EDIT:
If you don't want to use a debug message in your code all the time you could do it like this:
Create a class called settings:
public class Settings {
public static final boolean DEBUG = true;
// If you prefer you could do use an enum
// enum debugLevel {SHOW_EVERYMESSAGE, ERRORS, IMPORTANT_MESSAGES, ...}
// In your classes you would have to check that DEBUG is less or equal than
// the debugLevel you want
}
In classes where you want to use a debug message simply do this
import xxx.yyy.Settings
class foo {
final static boolean DEBUG = Settings.DEBUG;
if(DEBUG){
// Debug messages
}
}
Now if you want to disable DEBUG messages you could simply set DEBUG = false in your Settings class.
If you want to measure between two activities you could use intents and send t0 with an intent to the other activity to compute the time. Of course you could include this with if(DEBUG){ /* code */ } statements to spare the sending of the intent in the final release. The if statements should not increase the computation of your code too dramatically.

I cannot tell if Java offers a better implementation using System.currentTimeMillis() or System.nanoTime(). Nevertheless, you should give the TimingLogger class a try. Take a look at this article describing the usage of the TimingLogger helper class.

Android: How can I print a variable on eclipse console?

I wanted to print the value of a variable on the console for my debugging purpose, but System.out.println doesn't work.

System.out.println and Log.d both go to LogCat, not the Console.

Window->Show View->Other…->Android->LogCat

I'm new to Android development and I do this:
1) Create a class:
import android.util.Log;
public final class Debug{
private Debug (){}
public static void out (Object msg){
Log.i ("info", msg.toString ());
}
}
When you finish the project delete the class.
2) To print a message to the LogCat write:
Debug.out ("something");
3) Create a filter in the LogCat and write "info" in the input "by Log Tag". All your messages will be written here. :)
Tip: Create another filter to filter all errors to debug easily.

Writing the followin code to print anything on LogCat works perfectly fine!!
int score=0;
score++;
System.out.println(score);
prints score on LogCat.Try this

I think the toast maybe a good method to show the value of a variable!

Ok, Toast is no complex but it need a context object to work, it could be MyActivity.this, then you can write:
Toast.maketext(MyActivity.this, "Toast text to show", Toast.LENGTH_SHORT).show();
Although Toast is a UI resource, then using it in another thread different to ui thread, will send an error or simply not work
If you want to print a variable, put the variable name.toString() and concat that with text you want in the maketext String parameter ;)

toast is a bad idea, it's far too "complex" to print the value of a variable. use log or s.o.p, and as drawnonward already said, their output goes to logcat. it only makes sense if you want to expose this information to the end-user...

If the code you're testing is relatively simple then you can just create a regular Java project in the Package Explorer and copy the code across, run it and fix it there, then copy it back into your Android project.
The fact that System.out is redirected is pretty annoying for quickly testing simple methods, but that's the easiest solution I've found, rather than having to run the device emulator just to see if a regular expression works.

By the way, in case you dont know what is the exact location of your JSONObject inside your JSONArray i suggest using the following code: (I assumed that "jsonArray" is your main variable with all the data, and i'm searching the exact object inside the array with equals function)
JSONArray list = new JSONArray();
if (jsonArray != null){
int len = jsonArray.length();
for (int i=0;i<len;i++)
{
boolean flag;
try {
flag = jsonArray.get(i).toString().equals(obj.toString());
//Excluding the item at position
if (!flag)
{
list.put(jsonArray.get(i));
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
jsonArray = list;