接口的实现

在同一个activity中，有时listView中的item的数据的改变会影响listView外的数据，之前总是傻傻的使用广播通知界面更改。最近看了下接口的使用。直接贴代码。

activity中代码

privateTextViewtv_result;

privateListViewlv_goods;

privateListlist=newArrayList<>();

privateContextcontext;

privateGoodsAdapteradapter;

@Override

protected voidonCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

lv_goods= (ListView) findViewById(R.id.lv_goods);

tv_result= (TextView) findViewById(R.id.tv_result);

context=this;

list.add(newGoodsBean("10","0"));

list.add(newGoodsBean("8","0"));

list.add(newGoodsBean("7","0"));

list.add(newGoodsBean("3","0"));

adapter=newGoodsAdapter(context,list);

adapter.setIOnPriceListener(newGoodsAdapter.IOnPriceListener() {

@Override

public voidupdatePrice(Integer price) {

tv_result.setText(price+"");

}

});

lv_goods.setAdapter(adapter);

}

---

adapter中代码

privateContextmContext;

privateListmlist;

private intmoney=0;

publicIOnPriceListenerlistener;

public voidsetIOnPriceListener(IOnPriceListener listener) {

this.listener= listener;

}

public interfaceIOnPriceListener {

voidupdatePrice(Integer price);

}

publicGoodsAdapter(Context context,List list) {

mContext= context;

mlist= list;

for(inti =0;i

money+= Integer.parseInt(mlist.get(i).getPrice()) * Integer.parseInt(mlist.get(i).getNum());

}

}

@Override

public intgetCount() {

returnmlist!=null?mlist.size() :0;

}

@Override

publicObjectgetItem(inti) {

return null;

}

@Override

public longgetItemId(inti) {

return0;

}

ViewHolderholder=null;

@Override

publicViewgetView(final inti,View view,ViewGroup viewGroup) {

if(view ==null) {

holder=newViewHolder();

view = LayoutInflater.from(mContext).inflate(R.layout.item_goods,viewGroup, false);

holder.tv_add= (TextView) view.findViewById(R.id.tv_add);

holder.tv_minus= (TextView) view.findViewById(R.id.tv_minus);

holder.tv_price= (TextView) view.findViewById(R.id.tv_price);

holder.tv_num= (TextView) view.findViewById(R.id.tv_num);

view.setTag(holder);

}else{

holder= (ViewHolder) view.getTag();

}

holder.tv_price.setText(mlist.get(i).getPrice());

holder.tv_num.setText(mlist.get(i).getNum());

holder.tv_add.setOnClickListener(newView.OnClickListener() {

@Override

public voidonClick(View view) {

intnum = Integer.parseInt(mlist.get(i).getNum());

num++;

mlist.get(i).setNum(num +"");

holder.tv_num.setText(num +"");

money+= Integer.parseInt(mlist.get(i).getPrice());

notifyDataSetChanged();

if(listener!=null) {

listener.updatePrice(money);

}

}

});

holder.tv_minus.setOnClickListener(newView.OnClickListener() {

@Override

public voidonClick(View view) {

intnum = Integer.parseInt(mlist.get(i).getNum());

num--;

mlist.get(i).setNum(num +"");

holder.tv_num.setText(num +"");

notifyDataSetChanged();

money-= Integer.parseInt(mlist.get(i).getPrice());

if(listener!=null) {

listener.updatePrice(money);

}

}

});

returnview;

}

public classViewHolder {

publicTextViewtv_minus;

publicTextViewtv_add;

publicTextViewtv_price;

publicTextViewtv_num;

}