Question

当用户点击按钮时，一个名为＆＃34; startAThread＆＃34;开始，按钮变得不可见。三秒钟后线程完成工作后，按钮再次可见。当用户第二次点击按钮时，它会在LogCat中给出错误：

代码： -

public class MainActivity extends Activity {

Handler mHandler;
Button button;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    button = (Button)findViewById(R.id.button);
    mHandler = new Handler(Looper.getMainLooper());

    button.setOnClickListener(new View.OnClickListener()
    {
        @Override
        public void onClick(View view)
        {
            startAthread.start();
            button.setVisibility(View.INVISIBLE);
        }
    });

}

Thread startAthread = new Thread(new Runnable()
{
    @Override
    public void run()
    {
        try
        {
            Thread.sleep(3000);
        }
        catch (InterruptedException e)
        {
            e.printStackTrace();
        }

        mHandler.post(new Runnable()
        {
            @Override
            public void run()
            {
                button.setVisibility(View.VISIBLE);
            }
        });

    }
});
}

logcat的： -

01-10 19:45:39.861  22473-22473/com.guptamanish712.threadtest W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x418002b8)
01-10 19:45:39.891  22473-22473/com.guptamanish712.threadtest E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.IllegalThreadStateException: Thread already started.
            at java.lang.Thread.start(Thread.java:1045)
            at com.guptamanish712.threadtest.MainActivity$1.onClick(MainActivity.java:29)
            at android.view.View.performClick(View.java:4295)
            at android.view.View$PerformClick.run(View.java:17456)
            at android.os.Handler.handleCallback(Handler.java:615)
            at android.os.Handler.dispatchMessage(Handler.java:92)
            at android.os.Looper.loop(Looper.java:174)
            at android.app.ActivityThread.main(ActivityThread.java:4952)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1027)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:794)
            at dalvik.system.NativeStart.main(Native Method)

Answer 1

      button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            new Thread(new Runnable() {
                @Override
                public void run() {
                    try {
                        Thread.sleep(3000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }

                    mHandler.post(new Runnable() {
                        @Override
                        public void run() {
                            button.setVisibility(View.VISIBLE);

                        }
                    });

                }
            }).start();
            button.setVisibility(View.INVISIBLE);
        }
    });

Android线程没有结束。它无法重新开始

1 个答案: