Java 集合 初始化ArrayList

ArrayList<Type> obj = new ArrayList<Type>(
        Arrays.asList(Object o1, Object o2, Object o3, ....so on));

import java.util.*;
public class InitializationExample1 {
   public static void main(String args[]) {
       ArrayList<String> obj = new ArrayList<String>(
        Arrays.asList("Pratap", "Peter", "Harsh"));
      System.out.println("Elements are:"+obj);
   }
}

Elements are:[Pratap, Peter, Harsh]

ArrayList<T> obj = new ArrayList<T>(){{
           add(Object o1);
           add(Object o2);
           add(Object o3);
                   ...
                   ...
           }};

import java.util.*;
public class InitializationExample2 {
   public static void main(String args[]) {
       ArrayList<String> cities = new ArrayList<String>(){{
           add("Delhi");
           add("Agra");
           add("Chennai");
           }};
      System.out.println("Content of Array list cities:"+cities);
   }
}

Content of Array list cities:[Delhi, Agra, Chennai]

ArrayList<T> obj = new ArrayList<T>();
       obj.add("Object o1");
       obj.add("Object o2");
       obj.add("Object o3");
                        ...
                        ...

import java.util.*;

public class Details {
   public static void main(String args[]) {
       ArrayList<String> books = new ArrayList<String>();
       books.add("Java Book1");
       books.add("Java Book2");
       books.add("Java Book3");
      System.out.println("Books stored in array list are: "+books);
   }
}

Books stored in array list are: [Java Book1, Java Book2, Java Book3]

ArrayList<T> obj = new ArrayList<T>(Collections.nCopies(count, element));

import java.util.*;

public class Details {
   public static void main(String args[]) {
       ArrayList<Integer> intlist = new ArrayList<Integer>(Collections.nCopies(10, 5));
      System.out.println("ArrayList items: "+intlist);
   }
}

ArrayList items: [5, 5, 5, 5, 5, 5, 5, 5, 5, 5]