Java 如何使用getValue从HashMap中获取多个“一”值

我正在用JAVA编写一个程序，我正在使用HashMap

 private HashMap<Integer,Plane> planes;

然后，我尝试打印HashMap的所有组件，如下所示：

public void getAllAircrafts ()
{
    Set set = planes.entrySet();
    Iterator iterator = set.iterator();
    while(iterator.hasNext()) {
        Map.Entry mentry = (Map.Entry)iterator.next();
        System.out.print("Aircraft ID is: "+ mentry.getKey() + " ");
        System.out.println(mentry.getValue());
    }
}

---

问题是我想打印所有描述飞机的变量的值，但我得到的是飞机。Plane@15db9742来自mentry.getValue（）。如何解决此问题？

您需要为平面类重写并添加toString方法

    @Override
    public String toString() {
        return "Plane [planeNumber=" + planeNumber + 
                       ",departureTime=" + departureTime +  
                       ",arrivalTime=" + arrivalTime + 
                       ",flightDuration=" + flightDuration + 
                       ",aerialDrops=" + aerialDrops + "]";
    }

---

现在您正在使用对象类父对象的toString方法

您需要为平面类重写并添加一个toString方法

    @Override
    public String toString() {
        return "Plane [planeNumber=" + planeNumber + 
                       ",departureTime=" + departureTime +  
                       ",arrivalTime=" + arrivalTime + 
                       ",flightDuration=" + flightDuration + 
                       ",aerialDrops=" + aerialDrops + "]";
    }

---

现在您正在使用对象类父对象的toString方法，根据需要稍作更改即可：

   public class Plane {
   private int planeNumber;
   private int planeNumber;
   private int arrivalTime;
   private int flightDuration;
   private int aerialDrops;

   public String toString()
{
  return planeNumber +" "+planeNumber+" "+arrivalTime+" "+flightDuration+" "+aerialDrops
}
}

---

根据您的需要，稍作改动即可：

   public class Plane {
   private int planeNumber;
   private int planeNumber;
   private int arrivalTime;
   private int flightDuration;
   private int aerialDrops;

   public String toString()
{
  return planeNumber +" "+planeNumber+" "+arrivalTime+" "+flightDuration+" "+aerialDrops
}
}