code: public final void setMaxPriority(int pri) {
          int ngroupsSnapshot;
          ThreadGroup[] groupsSnapshot;
          synchronized (this) {
              checkAccess();
              // Android-changed: Clamp to MIN_PRIORITY, MAX_PRIORITY.
              // if (pri < Thread.MIN_PRIORITY || pri > Thread.MAX_PRIORITY) {
              //     return;
              // }
              if (pri < Thread.MIN_PRIORITY) {
                  pri = Thread.MIN_PRIORITY;
              }
              if (pri > Thread.MAX_PRIORITY) {
                  pri = Thread.MAX_PRIORITY;
              }
  
              maxPriority = (parent != null) ? Math.min(pri, parent.maxPriority) : pri;
              ngroupsSnapshot = ngroups;
              if (groups != null) {
                  groupsSnapshot = Arrays.copyOf(groups, ngroupsSnapshot);
              } else {
                  groupsSnapshot = null;
              }
          }
          for (int i = 0 ; i < ngroupsSnapshot ; i++) {
              groupsSnapshot[i].setMaxPriority(pri);
          }
      }
docs: before using it.