解决了！需要说明的是，我的应用程序由3个类组成：实用程序、主活动和事件。
首先，在Utils.java中解析JSON图标：

/**URL for the icons location at OpenWeatherMap*/
    public static final String IMG_URL = "https://openweathermap.org/img/w/";

 //Retrieve icon code from website
                String iconName = JSONWeather.getString("icon");

其次，在Event.java中添加：

在顶端

public final String iconName;

和阶级

public Event(.....String eventIconName)
{ .......
     iconName=eventIconName;
      }

第三，在MainActivity.java中添加图像视图和毕加索参考：

//Convert icon code from the OpenWeatherMap website into the image and insert into the ImageView. Path consists of URL declared in Utils.java, and @param iconName, declared in Event.java.
// JSON parser method used in Utils.java class retrieves icon code from OpenWeatherMap (iconName), .png extension is added.

    ImageView iconView =  findViewById(R.id.condIcon);
    Picasso.with(this).load(IMG_URL + weather.iconName +".png").into(iconView);

坦率地说，我花了2天的时间才弄明白这一点。希望这对其他人有帮助。

下面是另一种方法，但格式仍然类似：

.then(function (data) {
      console.log(data);
      var currentIconDay0 = data.weather[0].icon;
      var weatherIconDay0 = document.getElementById('weatherIconDay0');
      var img0 = document.createElement("img");
      img0.src = 'https://openweathermap.org/img/w/' + currentIconDay0 + '.png'
                weatherIconDay0.appendChild(img0);