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[英]Cannot refer to a non-final variable i inside an inner class defined in a different method
[英]Cannot refer to non-final variable inside an inner class
我试图在ListView
每一行中有一个CountDownTimer
。 我可以为每行中的按钮设置onClick
方法的唯一地方是CustomListAdapter
。 但是我不能参考应该显示剩余时间的TextView
。 我收到此错误:
不能在不同方法中定义的内部类中引用非最终变量持有者
我曾尝试将持有人设置为最终,但后来我收到此错误:
不能分配最终的局部变量持有者。 必须为空且不使用复合赋值
这是我的代码:
public class CustomTimerRowAdapter extends ArrayAdapter < TimerRow > {
Context context;
int height;
public CustomTimerRowAdapter(Context context, int resourceId,
List < TimerRow > items) {
super(context, resourceId, items);
this.context = context;
// Height of screen from not Activity subclass
height = context.getResources().getDisplayMetrics().heightPixels;
}
/* private view holder class */
private class ViewHolder {
TextView txtTimer;
TextView txtName;
Button bStartStop;
}
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder = null;
final TimerRow rowItem = getItem(position);
LayoutInflater mInflater = (LayoutInflater) context
.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
if (convertView == null) {
convertView = mInflater.inflate(R.layout.timer_row, null);
holder = new ViewHolder();
// make layout params
holder.txtTimer = (TextView) convertView.findViewById(R.id.tvTimes);
holder.txtTimer.getLayoutParams().height = height / 10;
holder.txtName = (TextView) convertView.findViewById(R.id.tvName);
holder.txtName.getLayoutParams().height = height / 10;
holder.bStartStop = (Button) convertView
.findViewById(R.id.bStartStopTimer);
holder.bStartStop.getLayoutParams().height = height / 10;
convertView.setTag(holder);
} else
holder = (ViewHolder) convertView.getTag();
holder.txtName.setText(rowItem.getName());
holder.bStartStop.setOnClickListener(new OnClickListener() {
final ViewHolder temp = new ViewHolder();@
Override
public void onClick(View v) {
new CountDownTimer(30000, 1000) {
public void onTick(long millisUntilFinished) {
// THIS IS WHERE I CANNOT REFER TO THE NON-FINAL VARIABLE
holder.txtTimer.setText("seconds remaining: " + millisUntilFinished / 1000);
}
public void onFinish() {
holder.txtTimer.setText("done!");
}
}.start();
}
});
return convertView;
}
}
对于如何解决这个问题,有任何的建议吗?
这应该有效:
final ViewHolder holder;
即最初不要将其分配给 null。
而不是让holder
最终使用v.getParent()
来访问按钮上的 TextView,如下所示:
holder.bStartStop.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
View parent = (View)v.getParent();
final TextView txtTimer = parent.findViewById(R.id.tvTimes);
//... your code here...
}
});
在onTick
和onFinish
使用txtTimer
来更新 TextView 文本。
将ViewHolder holder
声明为类变量。 知道了? 不! 往下看。
您的 getView 将如下所示
private ViewHolder holder;
public View getView(int position, View convertView, ViewGroup parent) {
holder = null;
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