Java map getOrDefault返回对象时如何返回整数_Java

Java map getOrDefault返回对象时如何返回整数

java

Java map getOrDefault返回对象时如何返回整数,java,Java,假设我有一个轮胎的构造函数，它取两个整数，pressure和maxpresse public class Tire { private int pressure; private int maxPressure; public Tire(int pressure, int maxPressure){ this.pressure = pressure; this.maxPressure = maxPressure; } public int getPressur

假设我有一个轮胎的构造函数，它取两个整数，

pressure

和

maxpresse

public class Tire {
  private int pressure;
  private int maxPressure;
  public Tire(int pressure, int maxPressure){
    this.pressure = pressure;
    this.maxPressure = maxPressure;
  }
  public int getPressure(){return pressure;}
  public int getMaxPressure(){return maxPressure;}
}

//should be 25
tires.getOrDefault("Goodyear", defaultTirePressure).getPressure();

//should be 28 because there is no Michelin tire defined in tires
tires.getOrDefault("Michelin", defaultTirePressure).getPressure();

在我的主要课程中，我可以将一个新的

Tire

添加到名为

tires

的

HashMap

中，其中

pressure

为25，而

maxpression

为32

public Map<String, Tire> tires = new HashMap<>;
public int defaultTirePressure = 28;
tires.put("Goodyear", new Tire(25, 30));

显然，这不起作用，因为

defaultTirePressure

是一个整数，

tires

包含

Tire

对象

这是可行的，但有点长：

//will set someTirePressure to 25
if(tires.containsKey("Goodyear")){
  someTirePressure = tires.getValue("Goodyear").getPressure();
}else{
  someTirePressure = defaultTirePressure;
}

//will set anotherTirePressure to 28 because there is no Michelin tire defined in tires
if(tires.containsKey("Michelin")){
  anotherTirePressure = tires.getValue("Goodyear").getPressure();
}else{
  anotherTirePressure = defaultTirePressure;
}

在本例中是否没有使用getOrDefault的方法？我觉得我可能已经回答了我自己的问题。

为什么不在

getOrDefault

方法中为

Tire

对象提供默认压力作为默认值

tires.getOrDefault("Michelin", new Tire(25, defaultTirePressure)).getPressure();

您还可以使用默认的

Tire

对象

public final Tire defaultTire = new Tire(25,28);
tires.getOrDefault("Michelin", defaultTire).getPressure();

public Tire(int maxPressure) {
   this.maxPressure = maxPressure;
}

public final Tire defaultTire = new Tire(28);
tires.getOrDefault("Michelin", defaultTire).getPressure();

或者您也可以使用具有最大压力的单参数构造函数来创建deault

Tire

对象

public final Tire defaultTire = new Tire(25,28);
tires.getOrDefault("Michelin", defaultTire).getPressure();

public Tire(int maxPressure) {
   this.maxPressure = maxPressure;
}

public final Tire defaultTire = new Tire(28);
tires.getOrDefault("Michelin", defaultTire).getPressure();