Question

如何动态更改listview的单个项目的文本颜色？我想在Android中实现以下功能。

定期调用API并获取每个价格数据
在列表视图中打印
计算每个价格保证金
如果某个项目的边距为负，则将颜色更改为红色。加上是绿色的。

此功能通常出现在Cryptocurrency Apps中。像那样 https://www.youtube.com/watch?v=UuCkg_P6_Ws

我实施了1,2和3。如何实施4？如果你对此有所了解，请告诉我。

public class CoinAdapter extends ArrayAdapter<CoinItem> {
Context context;
LayoutInflater layoutInflater;
ArrayList<CoinItem> coinItem;
float x;
import android.content.Context;
import android.content.res.ColorStateList;
import android.graphics.Color;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import java.util.ArrayList;


public class CoinAdapter extends ArrayAdapter<CoinItem> {
Context context;
LayoutInflater layoutInflater;
ArrayList<CoinItem> coinItem;
float x;


public CoinAdapter(Context context, int resource, ArrayList<CoinItem> coinItem) {
    super(context, resource, coinItem);
    this.context = context;
    this.layoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    this.coinItem = coinItem;
}

public float diff(String btc_last, String btc_prelast) {
    x = Float.parseFloat(btc_last) - Float.parseFloat(btc_prelast);
    return x;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    if (null == convertView) {
        convertView = layoutInflater.inflate(R.layout.item_ticker, null);
    }

    ImageView icon_coin = (ImageView) convertView.findViewById(R.id.icon_coin);
    icon_coin.setImageBitmap(coinItem.get(position).getIcon_coin());

    TextView text_last = (TextView) convertView.findViewById(R.id.text_last);
    text_last.setText(coinItem.get(position).getText_last() + "円");
    if (x > 0) text_last.setTextColor(Color.GREEN);
    else if (x < 0) text_last.setTextColor(Color.RED);
    else text_last.setTextColor(Color.BLACK);

    TextView text_coin = (TextView) convertView.findViewById(R.id.text_coin);
    text_coin.setText(coinItem.get(position).getText_coin());

    TextView text_bid = (TextView) convertView.findViewById(R.id.text_bid);
    text_bid.setText("売値");

    TextView text_bid_price = (TextView) convertView.findViewById(R.id.text_bid_price);
    text_bid_price.setText(coinItem.get(position).getText_bid_price() + "円");

    TextView text_ask = (TextView) convertView.findViewById(R.id.text_ask);
    text_ask.setText("買値");

    TextView text_ask_price = (TextView) convertView.findViewById(R.id.text_ask_price);
    text_ask_price.setText(coinItem.get(position).getText_ask_price() + "円");

    return convertView;
}
}

调用API代码就是那样

    final Handler handler = new Handler();
    final int delay = 1000;
    btc_prelast="0";
    handler.postDelayed(new Runnable() {
        @Override
        public void run() {
            coin_btc.clone().enqueue(new Callback<Ticker>() {
                @Override
                public void onResponse(Call<Ticker> call, Response<Ticker> response) {
                    btc_last = Float.toString(response.body().getLast());
                    btc_bid = Float.toString(response.body().getBid());
                    btc_ask = Float.toString(response.body().getAsk());
                    coinItem.set(0, new CoinItem(BitmapFactory.decodeResource(getResources(), icon_coin[0]), btc_last, name_coin[0], btc_bid, btc_ask));
                    coinAdapter.diff(btc_last,btc_prelast);
                    btc_prelast = btc_last;
                    coinAdapter.notifyDataSetChanged();

                }
                @Override
                public void onFailure(Call<Ticker> call, Throwable t) {

                }
            });

Answer 1

我假设您在列表视图中已经在布局中有TextView。您所要做的就是调用TextView＃setTextColor。一个例子是：

TextView t = (TextView)v.findViewById(R.id.textviewname);
t.setTextColor(Color.RED);

Answer 2

简单地放置else条件就行了。

假设TextView的默认颜色为黑色。

if(x < 0 ){
  textview.setTextColor(Color.RED);
}else if(x > 0){
  textview.setTextColor(Color.GREEN);
}else{
  //your textview default colour
  textview.setTextColor(Color.BLACK);
}

Answer 3

在你的Getview方法中，检查你的保证金。

    if(margin > 0){textview.setTextColor(Color.GREEN);}
    else if(margin < 0){textview.setTextColor(Color.RED);}
    else {textview.setTextColor(Color.BLACK);}

检查此条款。

如何动态更改单个项目的文本颜色？

3 个答案: