Array inside arraylist access

问题

I am trying to access a variable that is stores as part of an object that is in an array. However that array is in an arraylist. How can access that variable? To make it clear, I have a car object that has speed. I placed 4 cars in an array. And that array is duplicated and put in an arraylist.

public int getSpeedOfCarA (int index) {//used to access the variable speed in an array
    return garage [index].getSpeed ();
     }

Now I was trying this but got stuck.

public int getSpeedOfCarB(int n){

carSpeeds.get(...); //not sure what to use here.
}

回答1:

To access things inside of other things, simply chain the access syntax together. For the example of getting a field inside an object inside an array inside a List, you would simply use

list.get(pos)[arrayPos].fieldName

You may be misunderstanding how ArrayList works however: When working with it, you never see the array, and in fact as far as syntax is concerned it doesn't matter whether it's implemented as an Array or as a LinkedList or whatever else. If so, you need not use any array operator, as the get method will do that for you:

list.get(pos).fieldName

回答2:

I prefer to use an Iterator to access the car object in the list.

ArrayList<Car> list = new ArrayList<Car>();
Iterator i = list.iterator();
while(i.hasNext()){
    Car car = i.next();
}

回答3:

Use,

for(Car[] carArrays : listOfCarArrays) {
    for (Car car : carArrays) {
        //do something with car like car.getSpeed();
    }
}

来源：https://stackoverflow.com/questions/29001953/array-inside-arraylist-access

标签

java

arrays

arraylist