2 sequential runnable

Good time of day, guys. I need help. I'm writing a plugin. Its essence lies in the periodic establishment and destruction of the block. I am creating 2 Bukkit Runnables. This works, but only if you specify the delay and execution time as 2 to 1. I require them to be executed sequentially.
The block is installed, then 3 minutes pass and the block breaks. After the next 7 minutes, the block again installed and again after 3 minutes block breaks. And so on indefinitely.

Thank you in advance. I appreciate your time.

 

I'd make an object to hold data on the block (location, material, last operation, last operation time) then make a collection of said objects and then a single runnable that runs every 20 ticks (but remember, the 20 ticks = 1 second is only under ideal conditions, it isn't 100%). Then in my runnable, I'd loop the collection and check if the object is ready to change state then act on it.

EDIT: I'm in a really boring meeting right now so I fired up Minecraft and figured I'd write up and test an example, lol. Here is the idea.

Code:

Main class {
  Create List of DynamicBlocks

  onEnable {
    Run timer method
  }

  timer method {
    runnable {
      Create iterator
      Loop iterator {
        Is obj not ready for change?  continue

        If obj is visible (unbroken) {
          Set the location's block to air
          Set visible to false since we broke it
          continue
        }

        Set the location's block to the right material
        Set visible to true
      }
    } Run task timer for 20 ticks
  }
}

BlockBreakEvent {
  Create a new DynamicBlock
  Is the DynamicBlock already in the collection?  return

  Set the visible to false, since this is BlockBreakEvent
  Add to the collection
}

DynamicBlock {
  private MyPlugin plugin = null;
  private Location loc = null;
  private long lastchanged = 0;
  private boolean isVisible = true;
  private Material mat = null;

  public DynamicBlock(MyPlugin plugin, Location loc, Material mat) {
    Set the passed vars and set lastchanged to now
  }

  Override equals to return true if the locations are the same

  public void setVisible(boolean isVisible) {
    Set isVisible and update lastchanged
  }

  public boolean isReadyToChange() {
    get int adjustment from config, using isVisible to determine the appropriate path
    Multiply adjustment by 1000
    Return current time greater than or equal to last changed plus adjustment
  }
}

Only problem I can see with this, now that I think about it, is by only using material stuff like stairs and whatnot would lose their orientation data. So I guess one should add blockdata to the dynamicblock object so that can be restored too.

 

Why not just put a scheduled task inside of a scheduled task, that way you can reuse the same variables.