ArrayList 的字符串作为参数并返回列表中的最后一项

Question

I need help on writing this function in Java.. I'm completely stuck A function: ArrayList of Strings as a parameter and return the last item in the list.

And I need an function: Arraylist of Strings as a parameter and return the size of the list.

Answer 1

Giving you an idea and example

import java.util.ArrayList; // import the ArrayList class

ArrayList<String> cars = new ArrayList<String>();

cars.add("Volvo");
cars.add("BMW");
cars.add("Ford");

For getting the last item

String lastItem(){
    return cars.get(cars.size()-1); //will give you Ford
}

For getting the size

int numberOfCars(){
   return cars.size();//will give you 3
}

Answer 2

public String getLastItemFromList(ArrayList<String> al) {
    if(al.isEmpty()) {
        return "";
    }
    return al.get(al.size()-1);
}

public int getSizeOfList(ArrayList<String> al) {
    return al.size();
}

Answer 3

Y u need separate methods ? You can access them by predefined methods of the ArrayList class.

As of what I understood, here is my help !

//return Last element
ArrayList<String> stringsList; //assign values

String getLastItem(ArrayList<String> list){
 return list.get(list.size()-1);
}

//return size of the list

int getSize(ArrayList<String> list){
 return list.size();
}