从ArrayList返回值

Question

I had this code working for an Array...then re-read the instructions to find it specifically calls for an array LIST. I cannot seem to convert the methods beneath to be acceptable for the ArrayList...Please assist in how I need to change the verbiage...See below for a sample method:

public static int returnMin(ArrayList intArr) 
{  //Return the Min Value.
int minValue = intArr.get(0);
for(int i=1;i < intArr.size(); i = i+1){
    if(intArr.get(i) < minValue)
    { minValue = intArr.get(i);
    }
}   
return minValue; 
}   

Answer 1

try casting the objects retrieved as in

int minValue = (Integer) intArr.get(0);

and again with

if((Integer)intArr.get(i) > minValue)

Answer 2

In your method declaration, change:
...(ArrayList intArr) { to ...(ArrayList<Integer> intArr) { .
This will make the elements in intArr Integer s and not an Object s. To learn more about generics in java, look at The Java™ Tutorials on Generics .

Answer 3

As your ArrayList work only with int values, you should specify the type of your ArrayList in you method parameter:

public static int returnMin(ArrayList<Integer> intArr) { . . . }

Why to specify the type?

Well if you does not specify, your ArrayList will accept any value (String, Integers and any other) so when you use arrayList.get(0) you don't know what type is in that position and that is why in your example you have to cast it to Integer. Always when you are working with only one type, you should specify the type of your List to avoid this.

Generics tutorial:
https://docs.oracle.com/javase/tutorial/java/generics/why.html