IllegalThreadStateException同一个线程

同一个Thread，只能start一次

//如下代码放入到点击事件里，第一次点击创建two这个Thread，之后的点击没有创建线程，出现错误
if (two == null) {
        two = new Thread(new Test2Runnable(lockObject));
  }
 two.start();

错误如下：

2020-10-26 14:43:39.059 10224-10224/com.example.uxin.myapplication E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.uxin.myapplication, PID: 10224
    java.lang.IllegalThreadStateException
        at java.lang.Thread.start(Thread.java:724)
        at threadtest.ThreadTestActivity.onClick(ThreadTestActivity.java:83)
        at android.view.View.performClick(View.java:6303)
        at android.view.View$PerformClick.run(View.java:24828)
        at android.os.Handler.handleCallback(Handler.java:789)
        at android.os.Handler.dispatchMessage(Handler.java:98)
        at android.os.Looper.loop(Looper.java:164)
        at android.app.ActivityThread.main(ActivityThread.java:6798)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)