Java中List集合的三種遍歷方式(全網最詳)


  List集合在Java日常開發中是必不可少的,只要懂得運用各種各樣的方法就可以大大提高我們開發的效率,適當活用各種方法才會使我們開發事半功倍。

  我總結了三種List集合的遍歷方式,下面一一來介紹。

 

  首先來創建一個實體類,以供下面使用。

public class News{
    private int id;
    private String title;
    private String author;
    
    public News(int id, String title, String author) {
        super();
        this.id = id;
        this.title = title;
        this.author = author;
    }
    
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

}

 

第一種、最基礎的遍歷方式:for循環,指定下標長度,使用List集合的size()方法,進行for循環遍歷

  

 
         

import java.util.ArrayList;

 
         

public class Demo01 {

 
         

  public static void main(String[] args) {

   ArrayList<News> list = new ArrayList<News>();
    
   list.add(new News(1,"list1","a"));
   list.add(new News(2,"list2","b"));
   list.add(new News(3,"list3","c"));
   list.add(new News(4,"list4","d"));
   for (int i = 0; i < list.size(); i++) {
            News s = (News)list.get(i);
            System.out.println(s.getId()+"  "+s.getTitle()+"  "+s.getAuthor());
    }
  }
}

 

第二種、較為簡潔的遍歷方式:使用foreach遍歷List,但不能對某一個元素進行操作(這種方法在遍歷數組和Map集合的時候同樣適用)

import java.util.ArrayList;

public class Demo02 {

  public static void main(String[] args) {

    ArrayList<News> list = new ArrayList<News>();

     list.add(new News(1,"list1","a"));
     list.add(new News(2,"list2","b"));
     list.add(new News(3,"list3","c"));
     list.add(new News(4,"list4","d"));

    for (News s : list) {
            System.out.println(s.getId()+"  "+s.getTitle()+"  "+s.getAuthor());
   }
  }
}

 

第三種適用迭代器Iterator遍歷:直接根據List集合的自動遍歷

 

import java.util.ArrayList;

public class Demo03 {

  public static void main(String[] args) {

   ArrayList<News> list = new ArrayList<News>();
    
   list.add(new News(1,"list1","a"));
   list.add(new News(2,"list2","b"));
   list.add(new News(3,"list3","c"));
   list.add(new News(4,"list4","d"));
   
     Iterator<News> iter = list.iterator();
     while (iter.hasNext()) {
            News s = (News) iter.next();
            System.out.println(s.getId()+"  "+s.getTitle()+"  "+s.getAuthor());
    }
  }
}    

 

上面三種遍歷方式差別不是特別大,在沒有特定的要求時,均可以使用。不過根據不同的特殊情況,要合理選擇方式,來提高開發的效率。


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