Java中的Java .util.ArrayList.addall() 方法

下面是Java中ArrayList的addAll()方法：

1. boolean addAll(Collection c) ：此方法将指定集合中的所有元素附加到此列表的末尾，按照指定集合的迭代器返回的顺序。如果在操作过程中修改了指定的集合，则此操作的行为未定义（意味着如果指定的集合是此列表，并且此列表非空，则此调用的行为未定义）。

   Parameters:
   c : This is the collection containing elements to be added to this list.
   Exception:
   NullPointerException : If the specified collection is null

   // Java program to illustrate
   // boolean addAll(Collection c)
   import java.io.*;
   import java.util.ArrayList;
     
   public class ArrayListDemo {
       public static void main(String args[])
       {
     
           // create an empty array list1 with initial 
           // capacity as 5
           ArrayList arrlist1 = 
                              new ArrayList(5);
     
           // use add() method to add elements in the list
           arrlist1.add(12);
           arrlist1.add(20);
           arrlist1.add(45);
     
           // prints all the elements available in list1
           System.out.println("Printing list1:");
           for (Integer number : arrlist1) 
               System.out.println("Number = " + number);        
     
           // create an empty array list2 with an initial
           // capacity
           ArrayList arrlist2 = 
                                new ArrayList(5);
     
           // use add() method to add elements in list2
           arrlist2.add(25);
           arrlist2.add(30);
           arrlist2.add(31);
           arrlist2.add(35);
     
           // let us print all the elements available in 
           // list2
           System.out.println("Printing list2:");
           for (Integer number : arrlist2) 
               System.out.println("Number = " + number);        
     
           // inserting all elements, list2 will get printed
           // after list1
           arrlist1.addAll(arrlist2);
     
           System.out.println("Printing all the elements");
           // let us print all the elements available in 
           // list1
           for (Integer number : arrlist1) 
               System.out.println("Number = " + number);        
       }
   }
   

   Output:Printing list1:
   Number = 12
   Number = 20
   Number = 45
   Printing list2:
   Number = 25
   Number = 30
   Number = 31
   Number = 35
   Printing all the elements
   Number = 12
   Number = 20
   Number = 45
   Number = 25
   Number = 30
   Number = 31
   Number = 35
   

   boolean addAll(int index, Collection c)：此方法将指定集合中的所有元素插入此列表，从指定位置开始。它将当前位于该位置的元素（如果有）和任何后续元素向右移动（增加它们的索引）。新元素将按照指定集合的迭代器返回的顺序出现在列表中。

   Parameters:
   index : The index at which to insert the first element from the specified collection.
   c : This is the collection containing elements to be added to this list.
   Exception:
   IndexOutOfBoundsException : If the index is out of range
   NullPointerException : If the specified collection is null

   // Java program to illustrate
   // boolean addAll(int index, Collection c)
   import java.io.*;
   import java.util.ArrayList;
     
   public class ArrayListDemo {
       public static void main(String args[])
       {
     
           // create an empty array list1 with initial
           // capacity 5
           ArrayList arrlist = 
                           new ArrayList(5);
     
           // using add() method to add elements in the 
           // list
           arrlist.add(12);
           arrlist.add(20);
           arrlist.add(45);
     
           // prints all the elements available in list1
           System.out.println("Printing list1:");
           for (Integer number : arrlist) 
               System.out.println("Number = " + number);        
     
           // create an empty array list2 with an initial
           // capacity
           ArrayList arrlist2 = 
                               new ArrayList(5);
     
           // use add() method to add elements in list2
           arrlist2.add(25);
           arrlist2.add(30);
           arrlist2.add(31);
           arrlist2.add(35);
     
           // prints all the elements available in list2
           System.out.println("Printing list2:");
           for (Integer number : arrlist2) 
               System.out.println("Number = " + number);        
     
           // inserting all elements of list2 at third 
           // position
           arrlist.addAll(2, arrlist2);
     
           System.out.println("Printing all the elements");
     
           // prints all the elements available in list1
           for (Integer number : arrlist) 
               System.out.println("Number = " + number);        
       }
   }
   

   Output:Printing list1:
   Number = 12
   Number = 20
   Number = 45
   Printing list2:
   Number = 25
   Number = 30
   Number = 31
   Number = 35
   Printing all the elements
   Number = 12
   Number = 20
   Number = 25
   Number = 30
   Number = 31
   Number = 35
   Number = 45