使用线程更改imageview中的图像

Question

我的代码出错了。为什么胡虎123123

Thread timer = new Thread()
{
    public void run()
    {
        try
        {
            sleep(1500);
            splash.setImgeResource(R.drawable.dilclogo);
            sleep(1500);
        }
        catch (InterruptedException e)
        {
            e.printStackTrace();
        }
        finally
        {
            Intent intent = new Intent(MainActivity.this, MenuScreen.class);
            startActivity(intent);
        }
    }
};
timer.start();

Answer 1

您应该在ui线程上更新ui。使用runonUithread。

  runOnUiThread(new Runnable() {

  @Override
  public void run() {
   // set image to imageview here
   // ui should be updated on the ui thread.
   // you cannot update ui from a background thread  
  }
 });

但我建议你使用一个处理器。

public class Splash extends Activity {

//stopping splash screen starting home activity.
private static final int STOPSPLASH = 0;
//time duration in millisecond for which your splash screen should visible to
  //user. here i have taken half second
private static final long SPLASHTIME = 500;

//handler for splash screen
private Handler splashHandler = new Handler() {
     @Override
     public void handleMessage(Message msg) {
          switch (msg.what) {
            case STOPSPLASH:
                //Generating and Starting new intent on splash time out 
                Intent intent = new Intent(Splash.this, 
                                         MainActivity.class);
                startActivity(intent);
                    Splash.this.finish(); 
                break;
          }
          super.handleMessage(msg);
     }
};

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.splash);

    //Generating message and sending it to splash handle 
    Message msg = new Message();
    msg.what = STOPSPLASH;
    splashHandler.sendMessageDelayed(msg, SPLASHTIME);
}
}

泼洒xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" android:background="@drawable/mydrawable">
     // have a imageview and set background to imageview   

</RelativeLayout>

使用处理程序和postdelayed

public class Splash extends Activity {
private static final int SPLASH_TIME = 2 * 1000;// 3 seconds

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.splash);
    ImageView iv= (ImageView) findViewById(R.id.imageView1);
    iv.setBackgroundResource(R.drawable.afor);
    try {
    new Handler().postDelayed(new Runnable() {

        public void run() {

            Intent intent = new Intent(Splash.this,
                MainActivity.class);
            startActivity(intent);

            Splash.this.finish();
        }


    }, SPLASH_TIME);

    } catch(Exception e)
       {
        e.printStacktrace();
       }
}


@Override
public void onBackPressed() {
    this.finish();
    super.onBackPressed();
}
}

泼洒xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" android:background="#ffffaa">

<ImageView
    android:id="@+id/imageView1"
    android:layout_width="wrap_content"
    android:layout_height="fill_parent"
    android:layout_centerInParent="true"
     />

</RelativeLayout>

Answer 2

将splash.setImgeResources（R.drawable.dilclogo）；行放入runOnUiThread。

Thread timer = new Thread()
            {
                public void run()
                {
                    try
                    {
                        sleep(2000);
                       runOnUiThread(new Runnable() {
                        public void run() {
                             splash.setImageResource(R.drawable.billboard_image);
                        }
                    });

                        sleep(2000);
                        runOnUiThread(new Runnable() {
                            public void run() {
                                 splash.setImageResource(R.drawable.square);
                            }
                        });
                    }
                    catch (InterruptedException e)
                    {
                        e.printStackTrace();
                    }
                    finally
                    {
                       System.out.println("finally");
                    }
                }
            };
            timer.start();

Answer 3

这是因为您不能直接从任何其他线程访问UI/主线程。您可以使用以下方法访问UI线程：

1. 使用AsyncTask

您也可以阅读这篇关于android线程的文章，以帮助您更好地理解这个概念。