まずこれが、カウントダウンクラス
class countDown implements Runnable {

private int n;
private int pause; // in seconds

countDown(int p, int t){
n = p; pause = t;
}

public void run() {
for (int j = n;j > 0;j = j - 1) {
System.out.println(j,4);
try {
Thread.sleep(pause);
} catch(InterruptedException e) {return;}
}