如何遍历数组以查找参数是否与数组中的元素匹配？

Question

String[] arr = new String[3];
public static void main(String args[]){
        classname n = new classname();
        arr[0] = "bob";
        arr[1] = "Lisa";
        arr[2] = "Rob";
        n.applesEaten(bob,5)
        n.applesEaten(bob,9)
        n.applesEaten(bob,5)
        n.applesEaten(Lisa,3)
        n.applesEaten(Lisa,5)
        n.applesEaten(Rob,7)
}
public int applesEaten(String name, int apples){
        //because this method was called 3 times for bob and bob ate 5+9+5 apples,
//this method should return 19. and 8 for Lisa, 7 for Rob.
}

I tried using a single for-loop that traverses through arr array, however, the loop adds everyone's apple, how do I make it so that this method can return the different amount of apples for different names?

Answer 1

You need a Map instead of an Array, like this:

private static Map<String,Integer> arr = new HashMap<>(  );

public static void main(String args[]){

    applesEaten("bob",5);
    applesEaten("bob",9);
    applesEaten("bob",5);
    applesEaten("Lisa",3);
    applesEaten("Lisa",5);
    applesEaten("Rob",7);
}
public static int applesEaten(String name, int apples)
{
    return arr.compute(name, (k,v) -> (v == null) ? apples : v+apples );
}

As requested, an Array only solution [But don't do this :)]:

private static String[] arr = new String[3];

public static void main(String args[])
{
    arr[0] = "bob";
    arr[1] = "Lisa";
    arr[2] = "Rob";
    applesEaten("bob",5);
    applesEaten("bob",9);
    applesEaten("bob",5);
    applesEaten("Lisa",3);
    applesEaten("Lisa",5);
    applesEaten("Rob",7);
}
public static int applesEaten(String name, int apples)
{

    for ( int i = 0; i < arr.length; i++ )
    {
        String[] split = arr[i].split( "-" );
        if(split[0].equals( name ))
        {
            if(split.length==1)
            {
                arr[i]=name+"-"+apples;
                return apples;
            }
            else
            {
                int newApples = (Integer.parseInt( split[1] )+apples);
                arr[i]=name+"-"+newApples;
                return newApples;
            }

        }
    }
    return 0;
}