Android, how to get app on foreground

Question

I'm trying to develop a service that whenever an user opens an app my service will identify it. I'm using the files: /proc/[pid]/cgroup,/proc/[pid]/cmdline,/proc/[pid]/oom_score,/proc/[pid]/oom_score_adj to check if it's an user app running on foreground. Actually it's working but when I try to open any game the service won't recognize it all the time. (The service only identify the files (oom_score) that has the lowest value).

Example: oom_score for "com.google.android.googlequicksearchbox:interactor" is 75, but for "com.king.candycrushsaga" will be >150, so it will never be detected by the code (as it follows).

Service code:

scheduler.scheduleAtFixedRate(new Runnable() {
    @Override
    public void run() {
        s=appManager.getAppRunningForeground();
        System.out.println(s);
    }
},1,2,SECONDS);

Function that gets the app running:

private ReadWriteFile readWriteFile = new ReadWriteFile();
public String getAppRunningForeground(){
    int pid;
    File[] files = new File("/proc").listFiles();
    int lowestOomScore = Integer.MAX_VALUE;
    String foregroundProcess = null;
    for (File file : files) {
        if (!file.isDirectory() || (!file.getName().matches(("\\d+"))))
            continue;
        pid = Integer.parseInt(file.getName());
        try {
            String cgroup = readWriteFile.read(String.format("/proc/%d/cgroup", pid));
            String[] lines = cgroup.split("\n");
            if (lines.length != 2)
                continue;
            String cpuSubsystem = lines[0];
            String cpuaccctSubsystem = lines[1];
            if (!cpuaccctSubsystem.endsWith(Integer.toString(pid)) || cpuSubsystem.endsWith("bg_non_interactive"))
                continue;
            String cmdline = readWriteFile.read(String.format("/proc/%d/cmdline", pid));
            if (cmdline.contains("com.android.systemui")||cmdline.contains("com.google.android.googlequicksearchbox:interactor")) {
                continue;
            }
            int uid = Integer.parseInt(cpuaccctSubsystem.split(":")[2].split("/")[1].replace("uid_", ""));
            if (uid > 1000 && uid <= 1038)//System process
                continue;
            File oomScoreAdj = new File(String.format("/proc/%d/oom_score_adj", pid));
            if (oomScoreAdj.canRead()) {
                int oomAdj = Integer.parseInt(readWriteFile.read(oomScoreAdj.getAbsolutePath()));
                if (oomAdj != 0) {
                    continue;
                }
            }
            int oomscore = Integer.parseInt(readWriteFile.read(String.format("/proc/%d/oom_score", pid)));
            if (oomscore < lowestOomScore) {
                lowestOomScore = oomscore;
                foregroundProcess = cmdline.replaceAll("\\p{Cntrl}", "");
            }

        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    return foregroundProcess;
}

Class that reads a file.

public class ReadWriteFile{
    File file;
    StringBuilder teste3 = new StringBuilder();
    FileOutputStream outputStream;
    public static String read(String path) throws IOException {
        StringBuilder output = new StringBuilder();
        BufferedReader reader = new BufferedReader(new FileReader(path));
        output.append(reader.readLine());
        for (String line = reader.readLine(); line != null; line = reader.readLine())
            output.append('\n').append(line);
        reader.close();
        return output.toString();
    }
}

P.S: getRunningTasks is deprecated, so please, don't suggest it.

Answer 1

You can use UsageStatsManager class added in android api 21. See this question raised and answered by me.

The above answer will provide you an sorted applications ArrayList, required foreground application will the first one in the ArrayList on the index number 0.

Hope this will help.