Java Java.util.ArrayList.addall()用法及代码示例

以下是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按指定集合的​​Iterator返回的顺序附加到此列表的末尾。如果在操作进行过程中修改了指定的集合，则此操作的行为是不确定的(如果指定的集合是此列表，并且此列表是非空的，则表示此调用的行为是不确定的)。

   参数:
   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<Integer> arrlist1 =  
                              new ArrayList<Integer>(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<Integer> arrlist2 =  
                                new ArrayList<Integer>(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)：此方法从指定位置开始将指定集合中的所有元素插入此列表。它将当前位于该位置的元素(如果有)和任何后续元素右移(增加其索引)。新元素将按照指定集合的​​迭代器返回的顺序显示在列表中。

   参数:
   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<Integer> arrlist =  
                           new ArrayList<Integer>(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<Integer> arrlist2 =  
                               new ArrayList<Integer>(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