Detailed explanation of how Android gets the total number of processes, memory and task list

Android gets the total number of processes, memory, and task list

In Android development, sometimes we need to monitor the performance of the device, such as viewing the total number of currently running processes, available memory, and a list of running tasks. This information is very helpful for optimizing application performance and resource management. This article will introduce how to obtain this information through the Android API.

1. Get the total number of processes

In Android, you can get the total number of processes running on the current device through the ActivityManager class. Here is a simple example code:

import ;
import ;
 
public class ProcessInfo {
    public static int getProcessCount(Context context) {
        ActivityManager activityManager = (ActivityManager) (Context.ACTIVITY_SERVICE);
        List<> processList = ();
        return processList != null ? () : 0;
    }
}

How to use

Just call the (context) method where you need to get the total number of processes.

2. Obtain memory information

Android provides classes to obtain memory information, including total memory, available memory, etc. Here is a code example of how to get this information:

import ;
import ;
 
public class MemoryInfo {
    public static  getMemoryInfo(Context context) {
        ActivityManager activityManager = (ActivityManager) (Context.ACTIVITY_SERVICE);
         memoryInfo = new ();
        (memoryInfo);
        return memoryInfo;
    }
 
    public static long getTotalMemory(Context context) {
         memoryInfo = getMemoryInfo(context);
        return ; // Total memory (bytes)    }
 
    public static long getAvailableMemory(Context context) {
         memoryInfo = getMemoryInfo(context);
        return ; // Available memory (bytes)    }
 
    public static boolean isLowMemory(Context context) {
         memoryInfo = getMemoryInfo(context);
        return ; // Is it in a low memory state    }
}

How to use

Get total memory: (context)
Get available memory: (context)
Check if it is in a low memory state: (context)

3. Get the task list

To get a list of tasks running on the current device, you can use the getRunningTasks method in ActivityManager. It should be noted that starting from Android 5.0 (API level 21), in order to protect user privacy, the results returned by this method are limited to the caller's own tasks.

import ;
import ;
import ;
 
import ;
 
public class TaskInfo {
    public static List&lt;RunningTaskInfo&gt; getRunningTasks(Context context) {
        ActivityManager activityManager = (ActivityManager) (Context.ACTIVITY_SERVICE);
        return (Integer.MAX_VALUE); // Get all tasks    }
}

How to use

Call the (context) method where you need to get the task list, and then iterate over the returned List<RunningTaskInfo> object to get information for each task.

Things to note

When using the above method, make sure your application has obtained the corresponding permissions. For example, accessing a task list may require GET_TASKS permission.

Starting from Android 5.0, the behavior of the getRunningTasks method is limited, mainly to protect user privacy. Therefore, in higher version systems, this method may not return a full task list.

Through the above method, developers can easily obtain the total number of processes, memory information and task list of devices in Android applications. This information is of great significance to optimizing application performance and improving user experience.

Method supplement

1. Get the total number of processes

To get the total number of processes currently running on the device, you can use the ActivityManager class. ActivityManager provides methods to access system services, including getting a list of running services, etc.

import ;
import ;
 
public class ProcessInfo {
    public static int getRunningProcessCount(Context context) {
        ActivityManager activityManager = (ActivityManager) (Context.ACTIVITY_SERVICE);
        List<> runningAppProcesses = ();
        return ();
    }
}

2. Obtain memory information

Getting the total and available memory of the device can be achieved through the ActivityManager and MemoryInfo objects. In addition, you can also obtain the memory usage of a specific application.

import ;
import ;
 
public class MemoryInfo {
    public static long getTotalMemory(Context context) {
         memoryInfo = new ();
        ActivityManager activityManager = (ActivityManager) (Context.ACTIVITY_SERVICE);
        (memoryInfo);
        return ; // Total memory size (unit: bytes)    }
 
    public static long getAvailableMemory(Context context) {
         memoryInfo = new ();
        ActivityManager activityManager = (ActivityManager) (Context.ACTIVITY_SERVICE);
        (memoryInfo);
        return ; // Available memory size (unit: bytes)    }
 
    public static long getAppMemoryUsage(Context context) {
        ActivityManager activityManager = (ActivityManager) (Context.ACTIVITY_SERVICE);
        int pid = ();
        for ( process : ()) {
            if ( == pid) {
                int[] pids = new int[]{pid};
                [] memInfo = (pids);
                return memInfo[0].getTotalPrivateDirty() * 1024L; // The size of private dirty memory occupied by the application (unit: bytes)            }
        }
        return -1;
    }
}

3. Get the task list

To get the currently running task list, you also need to use ActivityManager. This can help developers understand which apps are running in the foreground or background.

import ;
import ;
 
public class TaskList {
    public static List&lt;&gt; getRunningTasks(Context context) {
        ActivityManager activityManager = (ActivityManager) (Context.ACTIVITY_SERVICE);
        return (Integer.MAX_VALUE); // Get all tasks    }
}

Things to note

The above code needs to be run in an application with appropriate permissions. Especially starting with Android 5.0 (API level 21), it may require the GET_TASKS permission to obtain running application process information, but this permission is deprecated in Android 8.0 (API level 26) and later.

To obtain application memory usage, make sure your application has sufficient permissions to query other applications' information, or only query your own application information.

In practical applications, frequent call to these methods may consume more system resources, so it is recommended to arrange the call frequency reasonably according to actual needs.

1. Get the total number of processes

To get the total number of processes on the current device, you can use the ActivityManager class. This class provides methods to access system services, including information about running tasks and processes.

import ;
import ;
 
public int getProcessCount(Context context) {
    ActivityManager activityManager = (ActivityManager) (Context.ACTIVITY_SERVICE);
    List<> runningAppProcesses = ();
    return runningAppProcesses != null ? () : 0;
}

2. Obtain memory information

Obtaining memory information mainly includes obtaining total memory, available memory, etc. This information can also be obtained through the ActivityManager.

Get available memory

public long getAvailableMemory(Context context) {
    ActivityManager activityManager = (ActivityManager) (Context.ACTIVITY_SERVICE);
     memoryInfo = new ();
    (memoryInfo);
    return ; // Returns the available memory size, unit in bytes}

Get total memory

Getting the total memory requires reading the system's /proc/meminfo file, which usually requires root permissions. However, starting with API 16 (Android 4.1), total memory can be obtained directly through the ActivityManager.

public long getTotalMemory(Context context) {
    ActivityManager activityManager = (ActivityManager) (Context.ACTIVITY_SERVICE);
     memoryInfo = new ();
    (memoryInfo);
    if (.SDK_INT &gt;= .VERSION_CODES.JELLY_BEAN) {
        return ; // Returns the total memory size, unit in bytes    } else {
        // For older versions, other methods may be needed to get the total memory        return -1;
    }
}

3. Get the task list

Getting the task list can also be achieved through the ActivityManager. It should be noted here that starting from Android 5.0 (API 21), non-system applications cannot obtain a complete task list for privacy reasons. However, you can still obtain task information related to your own application.

import ;
import ;
 
public List&lt;&gt; getTaskList(Context context) {
    ActivityManager activityManager = (ActivityManager) (Context.ACTIVITY_SERVICE);
    return (Integer.MAX_VALUE); // Get a list of all tasks}

Things to note

Permissions: Getting the above information usually does not require special permissions, but specific permissions may be required if more sensitive operations are involved, such as getting detailed information from other applications.

Compatibility: Different Android versions may behave differently, especially when dealing with privacy and security. Make sure your app is adapted to the target version of Android system.

Performance: Frequent calls to these methods may have an impact on performance, so it is recommended to call only if necessary and optimize the call frequency.

The above is a detailed explanation of how Android gets the total number of processes, memory and task list. For more information about Android getting the total number of processes, memory and task list, please follow my other related articles!