从数组中删除最后一个元素

Question

I am trying to delete an element from an array depending on the method's argument. If the argument is the last element's position, I can't use the for loop and end up specifying an if statement just to satisfy that. Also trying to return the current name in that position after the deletion. I have tested and the following code works.

I am trying to see if there is a better way of producing the same result without the extra if statement. I tried looking up the Arrays Class and no static method there that seems to help either. Please advice if there is a better way of doing this method. Thanks.

public class ArrayTester {
    public static String[] array1 = new String[100];

    public static void main(String[] args) {
        remove(50);
        System.out.println(remove(50));
    }

    public static String remove(int name) {

        if(name == 99){
            array1[name] = null; 
            return array1[name]; 
        }

        else if (name >= 0 && name < 99){         
            for (int i=name; i < array1.length-1; i++){
                    array1[i] = array1[i+1];
            }
            return array1[name]; 
        }
        return null;  
    }
}

Answer 1

And with ArrayList??

import java.util.ArrayList;

public class RemoveArrayListElement {

    public static void main(String[] args) {

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

        //<E> it is return type of ArrayList

        arlist.add("First Element"); // adding element in ArrayList
        arlist.add("Second Element");
        arlist.add("Third Element");
        arlist.add("forth Element");
        arlist.add("fifth Element");

        // remove array list element by index number
        arlist.remove(3);

        // remove ArrayList element by Object value
        arlist.remove("fifth Element");


        // get elements of ArrayList 
        for(int i=0;i<arlist.size();i++)
        {
            System.out.println("ArrayList Element "+i+" :"+arlist.get(i));
        }
    }
}

Output:

Remove ArrayList Element 0 :First Element
Remove ArrayList Element 1 :Second Element
Remove ArrayList Element 2 :Third Element 

With ArrayList is easier, isn't it?

Answer 2

Looking at your code, you seem to want something like this -

if (name == 99) {
  try {
    return array1[name]; 
  } finally {
    array1[name] = null; 
  }
}

Answer 3

array1 = Arrays.copyOf(array1, 99);

Answer 4

You can simplify your code a little by excluding the if . Unfortunately, the loop has to stay - arrays provide contiguous storage, so you need to move the data if you are to delete an item in the middle of the array.

public static String remove(int index) {
    // Note the use of "index" instead of "name"
    if (index < 0 || index >= array1.length) {
        // A more common approach is to throw an exception,
        // but your code returns null for out-of-range index
        return null;
    }
    for (int i = index; i < array1.length-1 ; i++) {
        array1[i] = array1[i+1];
    }
    // Unconditionally set null in the last element of the array
    array1[array1.length-1] = null;
    return array1[index]; 
}

Answer 5

Sounds to me like you would be better off using an ArrayList. Arrays aren't really made for what you're doing. But you could also just null the value at the desired location and run the java.util.Arrays.sort method on the array. Something like this (I'm winging it, but this would be close):

public static String remove(int name) {

    String returnValue = array1[name];
    array1[name] = null;
    java.util.Arrays.sort(array1);
    return returnValue;

}

This is going to leave you with a sorted array, but you're already shifting them out of their original indices anyway so that may or may not matter to you.

Another option would be to simply add a if (array1[index] != null) conditional to all of your code handling that array. That way you wouldn't have to shift your values around in the array and your code would just skip over any null values it runs into.