android通過代碼控制ListView上下滾動(dòng)
來源：程序員人生 發(fā)布時(shí)間：2015-03-16 10:52:57 閱讀次數(shù)：3011次
本文將介紹1種通過代碼控制ListView上下轉(zhuǎn)動(dòng)的方法。
先上圖：
按下按鈕會(huì)觸發(fā)ListView轉(zhuǎn)動(dòng)或停止。
實(shí)現(xiàn)該功能其實(shí)不難，下面給出主要代碼MainActivity.java
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; // 3個(gè)按鈕
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);
}
};
/**
* 向上轉(zhuǎn)動(dòng)
*/
public void listScrollUp() {
listScrollOff();
handler.postDelayed(run_scroll_up, 0);
}
/**
* 向下轉(zhuǎn)動(dòng)
*/
public void listScrollDown() {
listScrollOff();
handler.postDelayed(run_scroll_down, 0);
}
/**
* 停止轉(zhuǎn)動(dòng)
*/
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(⑴, 10);
handler.postDelayed(run_scroll_down, 10);
}
};
}
實(shí)現(xiàn)ListView位置變動(dòng)的是smoothScrollBy方法。
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.
工程源碼：
Android listview 代碼控制上下移動(dòng)
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