多執行緒實現順序迴圈列印

[quote]原題：有三個執行緒ID分別是A、B、C，請用多執行緒程式設計在螢幕上迴圈列印10次ABCABC…… 。[/quote]

package jstyle;

public class TestTread {
  private int i,j,count,times;
  private Object o = new Object();
  public void IdPrint(int t,String...ids){
    while(Thread.activeCount()!=1){
    	try {
			Thread.sleep(100);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		if(Thread.activeCount()==1){
			System.out.println();
		}
    }
    times = t;
    count = ids.length;
    for(i=0,j=0; j<count; j++){
      new Thread(new Runnable(){
        int pos = j;
        public void run(){
          synchronized (o) { 
            while(i<times*count){
              if(i%count==pos){
                i++;
                System.out.print(Thread.currentThread().getName());
                o.notifyAll();
              }
              try {
                o.wait();
              } catch (InterruptedException e) {
                e.printStackTrace();
              }
            }
            o.notifyAll();
          }
        };
      },ids[j]).start();    
    }
  }
  public static void main(String[] args) throws InterruptedException{
    new TestTread().IdPrint(9,"a","b","c");
    new TestTread().IdPrint(1,"d","e");
  }

}

abcabcabcabcabcabcabcabcabc
de

[quote]以上程式碼對該題做了適當擴充，支援不同的ID取值及列印次數，同時有效控制了併發可能引起的列印錯亂。

遺留問題：死鎖風險。就程式碼來看，任一執行緒異常中斷後，可能會造成其它執行緒持久wait。解決方法有待研究。[/quote]