最近項目中遇到倒計時的需求.在ListView中的每一個Item中,都有倒計時.使用了線程,每個1秒就刷新,發現效率太低下,同時,也造成了倒計時的錯亂.
這之前,先了解ListView 中的複用.
ViewHolder 是減少findViewById的次數;convertView.setTag(ViewHolder);是用來複用item資源的.當整個Item滑出整個屏幕後,就開始了資源複用.
之前的倒計時錯亂的原因和這個也有關係,倒計時創建了太多的線程,有的倒計時已經結束,但並未銷燬,複用的時候,就造成了錯亂.
遇到的第二個問題是:當上一個item滑出屏幕再滑回來後,倒計時又從最開始的時間開始了計時.解決的辦法很簡單:在設置倒計時之前,先保存獲取的倒計時時間,但是,保存的是倒計時時間+當前系統時間. 設置倒計時的時候,再取出來時間 - 當前系統時間,這樣就保證了無論怎麼滑動,顯示的時候,倒計時都是在減少.
不多說,看代碼:
1.倒計時代碼:
public class TimeCount extends LinearLayout {
/**聲明UI*/
private TextView tv_hour_decade;
private TextView tv_hour_unit;
private TextView tv_min_decade;
private TextView tv_min_unit;
private TextView tv_sec_decade;
private TextView tv_sec_unit;
private Context context;
/**定義long 類型變量*/
private long hour_decade;
private long hour_unit;
private long min_decade;
private long min_unit;
private long sec_decade;
private long sec_unit;
/**聲明 Timer*/
private Timer timer;
private ClockListener_My mClockListener;
private Handler handler = new Handler() {
public void handleMessage(Message msg) {
countDown();
};
};
/**
* 構造方法,加載倒計時樣式
* */
public TimeCount(Context context, AttributeSet attrs) {
super(context, attrs);
this.context = context;
LayoutInflater inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View view = inflater.inflate(R.layout.view_countdowntimer, this);
tv_hour_decade = (TextView) view.findViewById(R.id.tv_hour_decade);
tv_hour_unit = (TextView) view.findViewById(R.id.tv_hour_unit);
tv_min_decade = (TextView) view.findViewById(R.id.tv_min_decade);
tv_min_unit = (TextView) view.findViewById(R.id.tv_min_unit);
tv_sec_decade = (TextView) view.findViewById(R.id.tv_sec_decade);
tv_sec_unit = (TextView) view.findViewById(R.id.tv_sec_unit);
}
/**
* 倒計時開始
* */
public void start() {
if (timer == null) {
timer = new Timer();
timer.schedule(new TimerTask() {
@Override
public void run() {
handler.sendEmptyMessage(0);
}
}, 0, 1000);
}
}
/**
* 倒計時停止
*/
public void stop() {
if (timer != null) {
timer.cancel();
timer = null;
}
}
/**
*設置倒計時 時間
*
*/
public void setTimeEnd(long time2){
long day = time2 / (24 * 60 * 60);
long hour = (time2 % (24 * 60 * 60)) / (60 * 60);
long min = ((time2 % (24 * 60 * 60)) % (60 * 60)) / 60;
long sec = ((time2 % (24 * 60 * 60)) % (60 * 60)) % 60;
if (hour == 0 && min == 0 && sec == 0) {
tv_hour_decade.setText(0 + "");
tv_hour_unit.setText(0 + "");
tv_min_decade.setText(0 + "");
tv_min_unit.setText(0 + "");
tv_sec_decade.setText(0 + "");
tv_sec_unit.setText(0 + "");
mClockListener.timeEnd();
} else {
hour_decade = hour / 10;
hour_unit = hour - hour_decade * 10;
min_decade = min / 10;
min_unit = min - min_decade * 10;
sec_decade = sec / 10;
sec_unit = sec - sec_decade * 10;
tv_hour_decade.setText(hour_decade + "");
tv_hour_unit.setText(hour_unit + "");
tv_min_decade.setText(min_decade + "");
tv_min_unit.setText(min_unit + "");
tv_sec_decade.setText(sec_decade + "");
tv_sec_unit.setText(sec_unit + "");
}
}
/**
* 設置倒計時的顯示
*/
private void countDown() {
if (isCarry4Unit(tv_sec_unit)) {
if (isCarry4Decade(tv_sec_decade)) {
if (isCarry4Unit(tv_min_unit)) {
if (isCarry4Decade(tv_min_decade)) {
if (isCarry4Unit(tv_hour_unit)) {
if (isCarry4Decade(tv_hour_decade)) {
stop();
tv_hour_decade.setText(0 + "");
tv_hour_unit.setText(0 + "");
tv_min_decade.setText(0 + "");
tv_min_unit.setText(0 + "");
tv_sec_decade.setText(0 + "");
tv_sec_unit.setText(0 + "");
mClockListener.timeEnd();
}
}
}
}
}
}
}
/**
* 設置倒計時的十位 顯示
*/
private boolean isCarry4Decade(TextView tv) {
int time = Integer.valueOf(tv.getText().toString());
time = time - 1;
if (time < 0) {
time = 5;
tv.setText(time + "");
return true;
} else {
tv.setText(time + "");
return false;
}
}
/**
* 設置倒計時的個位顯示
*/
private boolean isCarry4Unit(TextView tv) {
int time = Integer.valueOf(tv.getText().toString());
time = time - 1;
if (time < 0) {
time = 9;
tv.setText(time + "");
return true;
} else {
tv.setText(time + "");
return false;
}
}
/**
* 設置監聽方法
* */
public void setClockListener_My(ClockListener_My clockListener) {
this.mClockListener = clockListener;
}
/**
* 定義接口
* */
public interface ClockListener_My {
void timeEnd();
void remainFiveMinutes();
}
}2.倒計時的佈局文件
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:padding="10dp" >
<TextView
android:id="@+id/tv_hour_decade"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="0"
android:textColor="@color/gray"
android:textSize="11sp" />
<TextView
android:id="@+id/tv_hour_unit"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="0"
android:textColor="@color/gray"
android:textSize="11sp" />
<TextView
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:gravity="center"
android:text="時"
android:textColor="@color/gray"
android:textSize="11sp" />
<TextView
android:id="@+id/tv_min_decade"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="0"
android:textColor="@color/gray"
android:textSize="11sp" />
<TextView
android:id="@+id/tv_min_unit"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="0"
android:textColor="@color/gray"
android:textSize="11sp" />
<TextView
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:gravity="center"
android:text="分"
android:textColor="@color/gray"
android:textSize="11sp" />
<TextView
android:id="@+id/tv_sec_decade"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="0"
android:textColor="@color/gray"
android:textSize="11sp" />
<TextView
android:id="@+id/tv_sec_unit"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="0"
android:textColor="@color/gray"
android:textSize="11sp" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="秒"
android:textColor="@color/gray"
android:textSize="11sp" />
</LinearLayout>3.佈局item
<*******.TimeCount
android:id="@+id/clock"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_centerVertical="true"
android:layout_marginRight="22dp"
android:text="00:00:00"
android:textColor="@color/gray"
android:textSize="11sp"
android:visibility="visible" />4.保存倒計時時間
for(int i = 0;i<list.size();i++){
long currentTime = System.currentTimeMillis();
String time1 = list.get(i).getTime();
if(TextUtils.isEmpty(time1) && TextUtils.equals(time1, "0")){
list.get(i).setTime(String.valueOf(currentTime));
}else{
long time2 = currentTime + Long.parseLong(time1) * 1000;
list.get(i).setTime(String.valueOf(time2));
}
}5.在listView的適配器中,設置倒計時
long time2 =list.get(position).getTime();
holder.time.setEndTime(time2);
holder.time.start();
其中,還有一些小細節,只能調試的時候,一一去做限制,增前代碼的健壯性.....