Cum se repetă prin Lista Java? Șapte (7) moduri de a repeta prin buclă în Java

Publicat: 2020-01-01

Cum se repetă prin Lista Java? Șapte (7) moduri diferite de a repeta prin buclă în Java

Cum se repetă prin Lista Java? Acest tutorial demonstrează utilizarea ArrayList, Iterator și Listă.

Există 7 moduri în care poți să iterați prin Listă.

  1. Simplu pentru buclă
  2. Bucla For îmbunătățită
  3. Iterator
  4. ListIterator
  5. buclă în timp ce
  6. Iterable.forEach() util
  7. Stream.forEach() util

Exemplu Java:

Aveți nevoie de JDK 13 pentru a rula sub program, deoarece point-5 mai sus folosește stream() util.

void java.util.stream.Stream.forEach (acțiunea Consumer<? super String>) efectuează o acțiune pentru fiecare element al acestui flux.

CrunchifyIterateThroughList.java
Java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
package crunchify . com . tutorials ;
 
import java . util . * ;
 
/**
* @author Crunchify.com
* How to iterate through Java List? Seven (7) ways to Iterate Through Loop in Java.
* 1. Simple For loop
* 2. Enhanced For loop
* 3. Iterator
* 4. ListIterator
* 5. While loop
* 6. Iterable.forEach() util
* 7. Stream.forEach() util
*/
 
public class CrunchifyIterateThroughList {
 
     public static void main ( String [ ] argv ) {
 
         // create list
         List <String> crunchifyList = new ArrayList <String> ( ) ;
 
         // add 4 different values to list
         crunchifyList . add ( "Facebook" ) ;
         crunchifyList . add ( "Paypal" ) ;
         crunchifyList . add ( "Google" ) ;
         crunchifyList . add ( "Yahoo" ) ;
 
         // Other way to define list is - we will not use this list :)
         List <String> crunchifyListNew = Arrays . asList ( "Facebook" , "Paypal" , "Google" , "Yahoo" ) ;
 
         // Simple For loop
         System . out . println ( "==============> 1. Simple For loop Example." ) ;
         for ( int i = 0 ; i < crunchifyList . size ( ) ; i ++ ) {
             System . out . println ( crunchifyList . get ( i ) ) ;
         }
 
         // New Enhanced For loop
         System . out . println ( "\n==============> 2. New Enhanced For loop Example.." ) ;
         for ( String temp : crunchifyList ) {
             System . out . println ( temp ) ;
         }
 
         // Iterator - Returns an iterator over the elements in this list in proper sequence.
         System . out . println ( "\n==============> 3. Iterator Example..." ) ;
         Iterator <String> crunchifyIterator = crunchifyList . iterator ( ) ;
         while ( crunchifyIterator . hasNext ( ) ) {
             System . out . println ( crunchifyIterator . next ( ) ) ;
         }
 
         // ListIterator - traverse a list of elements in either forward or backward order
         // An iterator for lists that allows the programmer to traverse the list in either direction, modify the list during iteration,
         // and obtain the iterator's current position in the list.
         System . out . println ( "\n==============> 4. ListIterator Example..." ) ;
         ListIterator <String> crunchifyListIterator = crunchifyList . listIterator ( ) ;
         while ( crunchifyListIterator . hasNext ( ) ) {
             System . out . println ( crunchifyListIterator . next ( ) ) ;
         }
 
         // while loop
         System . out . println ( "\n==============> 5. While Loop Example...." ) ;
         int i = 0 ;
         while ( i < crunchifyList . size ( ) ) {
             System . out . println ( crunchifyList . get ( i ) ) ;
             i ++ ;
         }
 
         // Iterable.forEach() util: Returns a sequential Stream with this collection as its source
         System . out . println ( "\n==============> 6. Iterable.forEach() Example...." ) ;
         crunchifyList . forEach ( ( temp ) - > {
             System . out . println ( temp ) ;
         } ) ;
 
         // collection Stream.forEach() util: Returns a sequential Stream with this collection as its source
         System . out . println ( "\n==============> 7. Stream.forEach() Example...." ) ;
         crunchifyList . stream ( ) . forEach ( ( crunchifyTemp ) - > System . out . println ( crunchifyTemp ) ) ;
     }
}

Ieșire:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
============== > 1. Simple For loop Example .
Facebook
Paypal
Google
Yahoo
 
============== > 2. New Enhanced For loop Example . .
Facebook
Paypal
Google
Yahoo
 
============== > 3. Iterator Example . . .
Facebook
Paypal
Google
Yahoo
 
============== > 4. ListIterator Example . . .
Facebook
Paypal
Google
Yahoo
 
============== > 5. While Loop Example . . . .
Facebook
Paypal
Google
Yahoo
 
============== > 6. Iterable . forEach ( ) Example . . . .
Facebook
Paypal
Google
Yahoo
 
============== > 7. Stream . forEach ( ) Example . . . .
Facebook
Paypal
Google
Yahoo
 
Process finished with exit code 0