在Android Java中使用Sleep()

Question

我正在按照本教程在程序中加载一个屏幕.教程说我的活动应该使用Sleep()命令Sleep(),但是它不能将Sleep()识别为函数并向我提供错误,询问我是否要创建一个名为Sleep()的方法.

这是代码示例:

public class LoadingScreenActivity extends Activity {

    //Introduce an delay
    private final int WAIT_TIME = 2500;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        System.out.println("LoadingScreenActivity screen started");

        setContentView(R.layout.loading_screen);
        findViewById(R.id.mainSpinner1).setVisibility(View.VISIBLE);

        new Handler().postDelayed(new Runnable(){ 

            @Override 
            public void run() {

                //Simulating a long running task
                this.Sleep(1000);
                System.out.println("Going to Profile Data");

                /* Create an Intent that will start the ProfileData-Activity. */
                Intent mainIntent = new Intent(LoadingScreenActivity.this,ProfileData.class); 
                LoadingScreenActivity.this.startActivity(mainIntent);
                LoadingScreenActivity.this.finish(); 
            } 
        }, WAIT_TIME);
    }
}

Answer 1

您可以使用以下方法之一:

Thread.sleep(timeInMills);

要么

SystemClock.sleep(timeInMills);

SystemClock.sleep(milliseconds)是一个非常类似的实用函数Thread.sleep(milliseconds),但它忽略了InterruptedException.如果不使用Thread.interrupt(),请使用此函数进行延迟,因为它将保留线程的中断状态.

Answer 2

功能是Thread.sleep(long).

但请注意,您不应在UI线程上执行睡眠.

Answer 3

你发布的代码太可怕了.请不要在实际设备上使用它.如果您运行与此类似的操作,您将收到"应用程序无响应"错误.

如果您正在使用处理程序,请记住在运行它的线程上创建了一个处理程序.因此,调用new Handler().post(...UI线程将在UI线程上执行runnable,包括这个"长时间运行的操作".优点是您可以为UI线程创建一个Handler,稍后您可以使用它,如下所示.

要将长时间运行的操作放入后台线程,您需要在runnable周围创建一个Thread,如下所示.现在,如果要在长时间运行的操作完成后更新UI,则需要使用处理程序将其发布到UI线程.

请注意,此功能非常适合使用此功能AsyncTask,使其看起来比下面的模式更清晰.但是,我将其包括在内以显示Handler,Threads和Runnables如何相关.

public class LoadingScreenActivity extends Activity {

//Introduce a delay
    private final int WAIT_TIME = 2500;
    private Handler uiHandler;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        uiHandler = new Handler(); // anything posted to this handler will run on the UI Thread
        System.out.println("LoadingScreenActivity  screen started");
        setContentView(R.layout.loading_screen);
        findViewById(R.id.mainSpinner1).setVisibility(View.VISIBLE);

        Runnable onUi = new Runnable() {
            @Override 
            public void run() {
                // this will run on the main UI thread 
                Intent mainIntent = new Intent(LoadingScreenActivity.this,ProfileData.class); 
                LoadingScreenActivity.this.startActivity(mainIntent); 
                LoadingScreenActivity.this.finish(); 
            }
        }; 

        Runnable background = new Runnable() { 
            @Override 
            public void run() { 
                // This is the delay
                Thread.Sleep( WAIT_TIME );
                // This will run on a background thread
                //Simulating a long running task
                Thread.Sleep(1000);
                System.out.println("Going to Profile Data");
                uiHandler.post( onUi );
            }
        };

        new Thread( background ).start(); 
}