线程池SingleThreadPool

只有一个核心线程，当被占用时，其他的任务需要进入队列等待

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final ExecutorService singleThreadExecutor = Executors.newSingleThreadExecutor();
        for(int i = 0;i<30;i++){
            final int finali = i;
            Runnable runnable = new Runnable() {
                @Override
                public void run() {
                    try {
                        Thread.sleep(2000);
                        Log.d("Thread", "run: "+finali);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            };
            singleThreadExecutor.execute(runnable);

        }
    }
}