检查元素是否在List中

import java.util.ArrayList;

public class ExistanceForList {

public static void main(String[] args) {
    // TODO Auto-generated method stub
    // create a new ArrayList of Strings with an initial capacity of 10
      ArrayList items = new ArrayList(); 

      items.add("red"); // append an item to the list          
      items.add(0, "yellow"); // insert "yellow" at index 0

      // check if a value is in the List
      System.out.printf("\"red\" is %sin the list%n",
         items.contains("red") ? "": "not ");

      // display number of elements in the List
      System.out.printf("Size: %s%n", items.size());

      items.remove(1); // remove item at index 1
      display(items, "Remove second list element (green):"); 

      // check if a value is in the List
      System.out.printf("\"red\" is %sin the list%n",
         items.contains("red") ? "": "not ");

      // display number of elements in the List
      System.out.printf("Size: %s%n", items.size());
   } 

   // display the ArrayList's elements on the console
   public static void display(ArrayList items, String header)
   {
      System.out.print(header); // display header

      // display each element in items
      for (String item : items)
         System.out.printf(" %s", item);

      System.out.println();
}

}
Console：
"red" is in the list
Size: 2
Remove second list element (green): yellow
"red" is not in the list
Size: 1