Develop Reference

How to get Total RAM memory of the Device?

When i run my app on LG G4 or Note 3 which has 3GB of RAM, it shows that the device has 2GB of ram. Can someone explain where is the problem?
ActivityManager.MemoryInfo mi = new ActivityManager.MemoryInfo();
ActivityManager activityManager = (ActivityManager) getSystemService(ACTIVITY_SERVICE);
activityManager.getMemoryInfo(mi);
long freeMemory = mi.availMem / 1048576L;
long totalMemory = mi.totalMem / 1048576L;
long usedMemory = totalMemory - freeMemory;
SharedPreferences sharedPreferences = getApplicationContext().getSharedPreferences(Util.MyPREFERENCES, 0);
String status = sharedPreferences.getString(Util.KEY_STATUS, null);
if (status.equals("clean")) {
tvFree.setText(freeMemory + " MB");
tvTotal.setText(totalMemory + " MB");
tvUsed.setText(usedMemory + " MB");
stateImage.setImageResource(R.drawable.greenstate);
rippleBackground.stopRippleAnimation();
}

It does not seem to be a clear API for that but I used a simple hack:
Setup a lookup table with some of the power of 2s (like first 15-20) and find the nearest value to the "OS memory" retrieved from the API.
Had a similar problem to yours:
Get android device's all RAM memory programmatically and not only what is only allocated to user processes

Lollipop: Get top activity name

How to get top activity name in Lollipop?
((ActivityManager)getSystemService(Context.ACTIVITY_SERVICE)).
getRunningTasks(1).get(0).topActivity
is not longer available for Lollipop:
* #deprecated As of {#link android.os.Build.VERSION_CODES#LOLLIPOP}, this method
* is no longer available to third party
* applications: the introduction of document-centric recents means
* it can leak person information to the caller. For backwards compatibility,
* it will still retu rn a small subset of its data: at least the caller's
* own tasks, and possibly some other tasks
* such as home that are known to not be sensitive.
Calling from onResume in MyActivity
MyApplication.getInstance().saveCurentActivity(MyActivity.this)
saveCurentActivity(Activity a) {
this.activityName = a.getClass().getSimpleName();
}
is no good idea, because MyApplication can be destroyed on error (for example, NPE).

This code is working for me.
ActivityManager activityManager = (ActivityManager) context.getSystemService(Activity.ACTIVITY_SERVICE);
List<ActivityManager.RunningTaskInfo> taskInfo = activityManager.getRunningTasks(1);
String currentTopActivity = taskInfo.get(0).topActivity.getClassName();
It will give TopActivity.

This worked for me:
long end = System.currentTimeMillis();
long INTERVAL=2000;
long begin = end - INTERVAL;
if (Build.VERSION.SDK_INT >= 21) {
UsageStatsManager us = (UsageStatsManager) MyServices.this.getSystemService(Context.USAGE_STATS_SERVICE);
UsageEvents usageEvents = us.queryEvents(begin, end);
while (usageEvents.hasNextEvent()) {
UsageEvents.Event event = new UsageEvents.Event();
usageEvents.getNextEvent(event);
if (event.getEventType() == UsageEvents.Event.MOVE_TO_FOREGROUND) {
Log.e("event", "timestamp : " + event.getTimeStamp());
Log.e("event", "package name : " + event.getPackageName());
Log.e("event", "Class name : " + event.getClassName());
//You can find activity name as Class name
}
}
}

I'm not familiar with the original API you are using, but you can track Activity life-cycle changes in your app, using an ActivityLifecycleCallbacks that could be registered via Application.registerActivityLifecycleCallbacks. It would get notified whenever an Activity is created, started, resumed, etc. You might be able to track the current Activity using the onActivityResumed and onActivityPaused hooks.

Android Running Task

How to get the list of applications which are currently running in android system and how to update it on the layout with their icon image.
And also help me to get all recent used application list and how to close one existing running application.
ActivityManager actvityManager = (ActivityManager) this.getSystemService(ACTIVITY_SERVICE);
List<RunningAppProcessInfo> procInfos = actvityManager.getRunningAppProcesses();
for (int i = 0; i < procInfos.size(); i++) {
String st = procInfos.get(i).processName + " " + String.valueOf(procInfos.get(i).processName.length());
//How to update it on layout in list format
}

Use custom listview.
create an array for app names and another for images(icons)
Then use custom listview to display it.
Here's a demo of custom listview

Android task killer

Im trying to write a simple task killer. I know I shouldnt kill tasks in Android, but Im eager to try something like this. I have the following code:
List<RunningAppProcessInfo> procInfo = activityManager.getRunningAppProcesses();
for (int i = 0; i < procInfo.size(); i++) {
Log.v("proces " + i,procInfo.get(i).processName + " pid:" + procInfo.get(i).pid + " importance: " + procInfo.get(i).importance + " reason: " + procInfo.get(i).importanceReasonCode);
//First I display all processes into the log
}
for (int i = 0; i < procInfo.size(); i++) {
RunningAppProcessInfo process = procInfo.get(i);
int importance = process.importance;
int pid = process.pid;
String name = process.processName;
if (name.equals("manager.main")) {
//I dont want to kill this application
continue;
}
if (importance == RunningAppProcessInfo.IMPORTANCE_SERVICE) {
//From what I have read about importances at android developers, I asume that I can safely kill everithing except for services, am I right?
Log.v("manager","task " + name + " pid: " + pid + " has importance: " + importance + " WILL NOT KILL");
continue;
}
Log.v("manager","task " + name + " pid: " + pid + " has importance: " + importance + " WILL KILL");
android.os.Process.killProcess(procInfo.get(i).pid);
}
procInfo = activityManager.getRunningAppProcesses();
//I get a new list with running tasks
for (int i = 0; i < procInfo.size(); i++) {
Log.v("proces after killings" + i,procInfo.get(i).processName + " pid:" + procInfo.get(i).pid + " importance: " + procInfo.get(i).importance + " reason: " + procInfo.get(i).importanceReasonCode);
}
My problem here is that when I perform this code, I first get the list of all tasks, thats ok. Than I see in the log several lines of:
Sending signal. pid: (processId) SIG: 9
I asume thats a signal to die. But at the end of my code, when I display all running processes, the list is the same as before, no task has been killed. Any ide why? Thank you!

You can't kill other tasks that way because the Kernel will enforce permissions. Try this instead:
ActivityManager activityManager = (ActivityManager) context.getSystemService("activity");
activityManager.restartPackage(packageName);
you will need the following permissions in the manifest:
<uses-permission android:name="android.permission.RESTART_PACKAGES" />
<uses-permission android:name="android.permission.KILL_BACKGROUND_PROCESSES" />
EDIT:
Actually restartPackage is deprecated. use killBackgroundProcesses() instead!

To achieve best result form killProcess , try calling killProcess many times.as
for (int i = 0; i < 10; i++)
{
android.os.Process.killProcess(procInfo.get(i).pid);
}
NOTE:
version ２.２
- killBackgroundProcesses : " This is the same as the kernel killing those processes to reclaim memory; the system will take care of restarting these processes in the future as needed."
ActivityManager am = (ActivityManager)getSystemService(ACTIVITY_SERVICE);
am.killBackgroundProcesses("com.est.testetst");
Required Permissions:
android.Manifest.permission.KILL_BACKGROUND_PROCESSES
version ２.１
- restartPackage -" This method is deprecated. (works for version less than 2.2.
This is now just a wrapper for killBackgroundProcesses(String); the previous behavior here is no longer available to applications because it allows them to break other applications by removing their alarms, stopping their services, etc."
ActivityManager am = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
am.restartPackage(getPackageName());
Required Permissions:
<uses-permission android:name="android.permission.RESTART_PACKAGES" />

Fortunately, killProcess() will only work for you to kill your own processes. You can tell this by reading the documentation.

What i am doing wrong to get the UID

I saw similar types of posts here.But i am not getting this right.To get the UID of running process i wrote
ActivityManager mgr = (ActivityManager) context.getSystemService(ACTIVITY_SERVICE);
List<RunningAppProcessInfo> processes = mgr.getRunningAppProcesses();
String text = "All Process:\n";
for (int i = 1; i <= processes.size(); i++)
{
String s;
s = processes.get(i - 1).processName.toString();
text += "Process:" + i + s + ":UID:" + android.os.Process.getUidForName(s) + "\n";
}
But after completion of loop what i am getting in the string text is all UID value as -1.I put GET_TASKS permission in manifest file.Why i am not getting the UID.Please help.I need this UID to kill the process.

To kill the process i used killBackgroundProcess Method of ActivityManager.It needs package name not the UID

Please see this answer by #seanhodges for reference.
Reading the whole thread might be helpful too.