Develop Reference

Android Studio shows old logs

I am using Android Studio v1.3.1 and when I am running a project on real device, I have to wait couple minutes till actual logs comes up in log console using Verbose & Show only selected application. If I choose No filtres it shows me older logs coming up, like 2-5 mins again. After all old logs are showed in console, it comes the news ones... I tried to restart logs, but it begins again to show old and then actual.
Any suggestions?

This issue(port issue) sometime happens if logcat does not clear the recent output caches on plugged devices.
AndroidStudio Solution (Clear all outputs and device ports)
Plug-Out your devices or close any emulators
File > Invalidate Caches / Restart > Press "Just Restart"
Also it's recommended to run any project with fully cleared logcat.
Run > Edit Configurations > Tab(Logcat) > CheckBox(Clear log before launch)
I personally would always log through terminal.
Terminal Solution
Just check if your device is plugged
path/to/android_sdk/platform-tools/./adb devices
Log your devices
path/to/android_sdk/platform-tools/./adb logcat
To get all logcat terminal options, see link below:
http://developer.android.com/tools/help/logcat.html

The entire log file is stored into the device storage, it can be extracted to the system so you can see the previous logs from the file.
Connect your device and run the command in terminal.
adb logcat -d > logcat.txt

Android app dumps stack trace, unable to open trace file

My Android app, which I'm running on a Samsung Galaxy S4 and starting via Eclipse, occasionally crashes. Instead of dumping a stacktrace to LogCat it says that it dumps it to /data/anr/traces.txt. The problem is I don't have permission to read the anr directory so 'adb pull /data/anr/traces.txt' just gives a permission denied error.
I just want to read my stacktrace. Is there anyway to force it to dump to LogCat? Or at least dump it to a file I have permission to read?
Much thanks...

You should be able to dump the logs locally like this:
adb logcat -d > log.txt

Unable to find android NDK stack-trace

I am developing an app that crashes in NDK code with SIG_SEGV. This causes the app to hang for about 15 seconds, then Android will prompt me to force close it. This prints the java stack-trace to logcat, but I don't see any stack-trace for the NDK. I have redirected stdio with ADB but I still don't see a stack-trace. How can I print C++ stack trace to logcat or where is being printed too?
Using Android 2.3.4
NDK r8b

The "force close" dialog is posted by the crashing application. This sounds like a Dalvik crash rather than a native crash. If the process is receiving a SIGSEGV it should be notifying debuggerd and exiting, leaving a trace in the log. It might be helpful to include logcat output from the crash in your question.
At any rate, recent versions of Android include the native traces mixed in with the Dalvik stack dump when threads are in native code. If you have a rooted device running a recent version of Android, you can ask debuggerd to dump a trace of all threads with adb shell debuggerd -b <pid>.
You're on Android 2.3.x, though, so none of that helps you. Your best option is to send the process a fatal signal to get the debuggerd crash dump. The signal must be sent twice, e.g.:
adb shell kill -6 <pid> ; sleep 1 ; adb shell kill -6 <pid>
This requires a rooted device, as the "shell" user can't send signals to arbitrary processes. Depending on what exactly is going on, you should be able to do this while the "force close" dialog is still on screen... but if the thread managed to crash without taking the process down then there may not be a stack to get a trace from.

You can use the following code to get Log
__android_log_print(ANDROID_LOG_ERROR, "TRACKERS", "%s", Str);
and add the following library
#include <android/log.h>

There is a tool called CheckJNI and the tutorial to set it up is there.

Where to find android crash history

I've been experiencing a great deal of instability on my Verizon Galaxy S III, and I believe it's related to the WiFi driver, or at least something in the networking stack. I get daily full system crashes that cause soft reboots of the OS.
In order to trace to the root of the issue, I'd like to see historical crash data for the Android OS. Please note that I am NOT developing an app, and I do not want instruction on how to use LogCat to trace issues within an in-development app. I want to see the Android system crash logs, but I'm not sure where to look for them.

After ANR happens, you would find call stack of related process at /data/anr/traces.txt
After application crashes, you might find call stack of crashed application under /data/tombstones directory.

See Android: How to get kernel logs after kernel panic?
It looks like /data/dontpanic/ should contain some "apanic" files, but only if the kernel's apanic support is enabled, and it worked. (I haven't seen anything there in my case, but maybe you'll be luckier than I ...)

crash report can be found at default path: /data/anr/
some manufacture place in custom path like: /data/system/ckerror
use cmd: adb pull /data/anr "dest path"
example:
in windows cmd prompt:
adb pull /data/anr c:\trace

The document states that
Android stores trace information when it experiences an ANR. On older OS releases, there's >a single /data/anr/traces.txt file on the device.
On newer OS releases, there are multiple >/data/anr/anr_* files. You can access ANR traces from a device or emulator by using >Android Debug Bridge (adb) as root:
adb root
adb shell ls /data/anr
adb pull /data/anr/<filename>

Usually the every crash is stored in traces.txt file under /data/anr/ folder of internal storage. Try checking this file.

I found a file call crash.txt inside the directory /data/Logging which seems to contain brief stack-traces from the last several crashes that occurred on the device.

Android: Logging on an android device

I am no good with hardware concepts. So I have this probably very silly doubt.
I want to add Log to my application. When running on an emulator, I know where to see the Log output - it's visible in the Logcat window of Eclipse.
I want to know where I can see these logs when I run it on a hardware device. I am using following command to load my app on to the device : ./adb install helloWorld.apk
So where will the log be created and under what name?
Apologies if the question is vague or silly. I really do not know more details.
-Kiki

Try to use:
./adb logcat

When you run on device, the log is also available in LogCat. You will need to turn on USB debugging (Settings > Applications > Development > USB Debugging) in your device, then you can use LogCat just like in the emulator, both using ./adb logcat and in Eclipse.