获取正在运行的进程的PID

Question

IAM试图获取具有包名的正在运行的进程的pid，IAM在android studio中使用C代码。当我在模拟器上返回pid时，代码为我提供了没有问题的真实pid  但是，当我在9.0设备上尝试时，结果iam getiing -1，我不知道问题出在哪里？

    articleListener = object : ValueEventListener {
        override fun onDataChange(dataSnapshot: DataSnapshot) {
            data = mutableListOf()

            for (article in dataSnapshot.children) {
                val articleData = article.getValue(Article::class.java)
                articleData?.id = article.key

                data.indexOfFirst { art -> art.id == article.key }.let {
                    //if ID exists then overrides else add
                    if (it != -1) {
                        articleData?.let { it1 -> data[it] = it1 }
                    } else
                        articleData?.let { it1 -> data.add(it1) }
                }
            }
        }

        override fun onCancelled(databaseError: DatabaseError) {
            // Getting Post failed, log a message
            Log.w("TAG", "loadPost:onCancelled", databaseError.toException())
        }
    }

    firebaseDatabase = try {
        FirebaseDatabase.getInstance().apply { setPersistenceEnabled(true) }
    } catch (e: Exception) {
        Log.w("Warn", e.toString())
        FirebaseDatabase.getInstance()
    }

                // I changed the container from articles to release_articles
    databaseReference = firebaseDatabase.reference.child("release_articles")
    databaseReference.orderByChild("date/time").startAt(getTodayInMillis().toDouble())
        .addValueEventListener(articleListener)

我还在启动应用程序时按Java授予了root权限