Using the ArrayList class

Common methods class ArrayList

(1) add an element

public boolean add (E element) add an element to the end of the collection

public void add (int index, E element) add an element to the specified index

(2) to obtain elements

public E get (int index) Returns the element at the specified index

(3) remove elements

public boolean remove (Object o) Removes the specified element, delete successful return

public E remove (int index) delete the element at the specified index and returns the removed element

(4) modify the element

public E set (int index, E element) to modify the element at the specified index, returns the modified element

(5) Get set length

public int size () returns the number of elements in the set

Example:

 1 import java.util.ArrayList;
 2 
 3 public class Demo01 {
 4     public static void main(String[] args) {
 5         // 创建集合对象
 6         ArrayList<String> arrayList=new ArrayList<String>();
 7 
 8         //添加String类型数据, public boolean add(E element)
 9         boolean b1 = arrayList.add("hello");
10         arrayList.add("world");
11         arrayList.add("inspur");
12 
13         System.out.println(arrayList);
14         System.out.println(b1);
15 
16         //添加String类型数据, public void add(int index, E element)
17         arrayList.add(1,"you");
18         arrayList.add(1,"we");
19 
20         System.out.println(arrayList);
21 
22         //获取数据 public E get(int index)
23         System.out.println(arrayList.get(2));
24 
25         //删除数据 public boolean remove(Object obj)
26 
27         boolean b2=arrayList.remove("Hello");
28         boolean b3=arrayList.remove("hello");
29         System.out.println("b2:"+b2+"   b3:"+b3);
30         System.out.println(arrayList);
31 
32         //删除数据 public E remove (int index)
33         String str1=arrayList.remove(0);
34         System.out.println("str1:"+str1);
35         System.out.println(arrayList);
36 
37         //修改数据 public E set(int index, E element)
38 
39         String str2 = arrayList.set(0,"first");
40         System.out.println("str2:"+str2);
41 is          System.out.println (the arrayList);
 42 is  
43 is          // Get set length 
44 is          int arraylength = arrayList.size ();
 45          System.out.println (arraylength);
 46 is  
47      }
 48 }

The output is:

[hello, world, inspur]
true
[hello, we, you, world, inspur]
you
b2:false   b3:true
[we, you, world, inspur]
str1:we
[you, world, inspur]
str2:you
[first, world, inspur]
3

ArrayList collections traversal

(1) for loop iterates (2) foreach traversal

Example:

. 1  public  class Demo02 {
 2      public  static  void main (String [] args) {
 . 3          // Create a set of objects 
. 4          the ArrayList <String> = the arrayList new new the ArrayList <String> ();
 . 5  
. 6          // add data of type String 
. 7          arrayList.add ( "Hello" );
 . 8          arrayList.add ( "World" );
 . 9          arrayList.add ( "Inspur" );
 10  
. 11          System.out.println (the arrayList);
 12 is  
13 is          // for loop iterates 
14         System.out.println ( "for loop traversal" );
 15          for ( int I = 0; I <arrayList.size (); I ++ ) {
 16              of System.out.print (arrayList.get (I) + "\ T " );
 . 17          }
 18 is          System.out.println ();
 . 19  
20 is          // foreach traverse 
21 is          System.out.println (" traversed using foreach " );
 22 is          for (String STR: the arrayList) {
 23 is              the System.out .print (STR + "\ T" );
 24          }
 25      }
 26 is }

The output is:

[hello, world, inspur] 
for loop traversal 
hello world inspur     
using foreach traverse 
hello world inspur