package cn.guet.levide; import andROId.app.Activity; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.ListView; public class MainActivity extends Activity implements OnClickListener {  PRivate Button BTn_up, btn_down, btn_stop; // 三个按钮  private ListView listview;  private Adapter adapter;  @override  public void onCreate(Bundle savedInstancestate) {  suPEr.onCreate(savedInstanceState);  setContentView(R.layout.main);  findBy();  init();  }  private void init() {  btn_up.setOnClickListener(this);  btn_down.setOnClickListener(this);  btn_stop.setOnClickListener(this);  adapter = new Adapter(this);  listview.setAdapter(adapter);  }  private void findBy() {  btn_up = (Button) findViewById(R.id.btn_scroll_up);  btn_down = (Button) findViewById(R.id.btn_scroll_down);  btn_stop = (Button) findViewById(R.id.btn_scroll_stop);  listview = (ListView) findViewById(R.id.listview);  }  @Override  public void onClick(View v) {  switch (v.getId()) {  case R.id.btn_scroll_down:   listScrollDown();   break;  case R.id.btn_scroll_up:   listScrollUp();   break;  case R.id.btn_scroll_stop:   listScrollOff();   break;  }  }  Handler handler = new Handler() {  @Override  public void handleMessage(Message msg) {   handler.removeCallbacks(run_scroll_down);   handler.removeCallbacks(run_scroll_up);  }  };  /**  * 向上滚动  */  public void listScrollUp() {  listScrollOff();  handler.postDelayed(run_scroll_up, 0);  }  /**  * 向下滚动  */  public void listScrollDown() {  listScrollOff();  handler.postDelayed(run_scroll_down, 0);  }  /**  * 停止滚动  */  public void listScrollOff() {  handler.removeCallbacks(run_scroll_down);  handler.removeCallbacks(run_scroll_up);  }  Runnable run_scroll_up = new Runnable() {  @Override  public void run() {   /**   * public void smoothScrollBy (int distance, int duration)    *    * Added in API level 8 Smoothly scroll by distance pixels over duration milliseconds.   *    * Parameters    *   distance Distance to scroll in pixels.   *   duration Duration of the scroll animation in milliseconds.   */   listview.smoothScrollBy(1, 10);   handler.postDelayed(run_scroll_up, 10);  }  };  Runnable run_scroll_down = new Runnable() {  @Override  public void run() {   listview.smoothScrollBy(-1, 10);   handler.postDelayed(run_scroll_down, 10);  }  }; }

 public void smoothScrollBy (int distance, int duration)   Smoothly scroll by distance pixels over duration milliseconds.  Parameters   distance Distance to scroll in pixels.   duration Duration of the scroll animation in milliseconds.