How to check if thread is alive after restarting an Activity?

Question

I am running a heavy operation on a thread, which is invoked on button click. To prevent user from clicking that button again, I am simply checking if thread.isAlive(), which runs fine as long as I am in the current activity. When I press backpress and come again to this activity, thread.isAlive() returns false and start executing that intensive function again because I am creating new thread in onCreate. How can I solve this? My code as under

 Thread thread;
     @Override
           protected void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
           setContentView(R.layout.activity_backup_restore);
           Backup backupobj= new Backup();
            thread= new Thread (new BackupThread(backupobj));

                  button.setOnClickListener(v -> { 
                  if(posts.size()>0) {

                 if (!thread.isAlive()) {
                   thread.start();

                 }
                 else {
                     Toast toast = Toast.makeText(getApplicationContext(), "Backup in Progress" , 
                     Toast.LENGTH_LONG);
                     toast.show();

                 }

         }
     });}

BackupThread class

class BackupThread extends Thread {
BackupRestore.Backup backup;

BackupThread(BackupRestore.Backup obj)
{
    this.backup=obj;
}


@Override
public void run() {

    backup.overallbackup();
    backup.dbbackup();
    backup.deletetempfolder();

}

Answer 1

To be precise,

Thread.isAlive() returns true if the thread has been started (may not yet be running) but has not yet completed its run method.

Thread.getState() returns the exact state of the thread.