android通过代码控制ListView上下滚动
来源：程序员人生 发布时间：2015-03-16 10:52:57 阅读次数：2881次
本文将介绍1种通过代码控制ListView上下转动的方法。
先上图：
按下按钮会触发ListView转动或停止。
实现该功能其实不难，下面给出主要代码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);
}
};
/**
* 向上转动
*/
public void listScrollUp() {
listScrollOff();
handler.postDelayed(run_scroll_up, 0);
}
/**
* 向下转动
*/
public void listScrollDown() {
listScrollOff();
handler.postDelayed(run_scroll_down, 0);
}
/**
* 停止转动
*/
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(⑴, 10);
handler.postDelayed(run_scroll_down, 10);
}
};
}
实现ListView位置变动的是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.
工程源码：
Android listview 代码控制上下移动
生活不易，码农辛苦
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