JAVAutil。ArrayList。Java中的addall（）方法

以下是 addAll（） 方法 ArrayList 在Java中：

1. 布尔addAll（集合c）： 此方法将指定集合中的所有元素按照指定集合的迭代器返回的顺序追加到此列表的末尾。如果在操作进行过程中修改了指定集合，则此操作的行为未定义（如果指定集合是此列表，且此列表非空，则表示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<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
   

   布尔addAll（整数索引，集合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）和任何后续元素向右移动（增加其索引）。新元素将按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<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
   

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