Java CopyOnWriteArrayList lastIndexOf()用法及代碼示例

• CopyOnWriteArrayList的lastIndexOf(Object o)方法返回列表中傳遞的元素的最後一次出現。如果列表中不存在該元素，則返回-1。

  用法:

  public int lastIndexOf(Object o)

  參數：該函數接受一個參數o，其最後一次出現將被返回。

  返回值：該函數返回該元素的最後一次出現。如果列表中不存在該元素，則返回-1。

  
  

  以下示例程序旨在說明上述函數：

  示例1:

  // Java Program to illustrate the CopyOnWriteArrayList 
  // lastIndexOf() method in Java 
  import java.util.concurrent.CopyOnWriteArrayList; 
  import java.util.*; 
    
  public class GFG { 
      public static void main(String[] args) 
      { 
    
          // create object of CopyOnWriteArrayList 
          CopyOnWriteArrayList<Integer> ArrLis 
              = new CopyOnWriteArrayList<Integer>(); 
    
          // Add elements 
          ArrLis.add(32); 
          ArrLis.add(67); 
          ArrLis.add(67); 
          ArrLis.add(100); 
    
          // print CopyOnWriteArrayList 
          System.out.println("CopyOnWriteArrayList: "
                                             + ArrLis); 
    
          // last occurrence of 67 
          System.out.println("lastIndexOf value: " 
                           + ArrLis.lastIndexOf(67)); 
      } 
  }

  輸出：

  CopyOnWriteArrayList: [32, 67, 67, 100]
  lastIndexOf value: 2
  

  示例2:

  // Java Program to illustrate the CopyOnWriteArrayList 
  // lastIndexOf() method in Java 
  import java.util.concurrent.CopyOnWriteArrayList; 
  import java.util.*; 
    
  public class GFG { 
      public static void main(String[] args) 
      { 
    
          // create object of CopyOnWriteArrayList 
          CopyOnWriteArrayList<Integer> ArrLis 
              = new CopyOnWriteArrayList<Integer>(); 
    
          // Add elements 
          ArrLis.add(32); 
          ArrLis.add(67); 
          ArrLis.add(67); 
          ArrLis.add(100); 
    
          // print CopyOnWriteArrayList 
          System.out.println("CopyOnWriteArrayList: " 
                                            + ArrLis); 
    
          // 200 is not present 
          System.out.println("lastIndexOf value: " 
                            + ArrLis.lastIndexOf(200)); 
      } 
  }

  輸出：

  CopyOnWriteArrayList: [32, 67, 67, 100]
  lastIndexOf value: -1
  

• CopyOnWriteArrayList的lastIndexOf(E e，int index)方法返回位置索引之後在列表中傳遞的元素的最後一次出現。如果列表中不存在該元素，則返回-1。

  用法:

  public int lastIndexOf(E e, int index)

  參數：該函數接受以下兩個參數：

  • index:指定要從中搜索事件的索引。
  • e：指定要返回位置索引中最後一次出現的元素。

  返回值：該函數返回位置索引之後元素的最後一次出現。如果列表中不存在該元素，則返回-1。

  異常：如果指定的索引為負，該函數將引發IndexOutOfBoundsException。

  以下示例程序旨在說明上述函數：

  
  

  示例1:

  // Java Program to illustrate the CopyOnWriteArrayList 
  // lastIndexOf() method in Java 
  import java.util.concurrent.CopyOnWriteArrayList; 
  import java.util.*; 
    
  public class GFG { 
      public static void main(String[] args) 
      { 
    
          // create object of CopyOnWriteArrayList 
          CopyOnWriteArrayList<Integer> ArrLis 
              = new CopyOnWriteArrayList<Integer>(); 
    
          // Add elements 
          ArrLis.add(32); 
          ArrLis.add(67); 
          ArrLis.add(67); 
          ArrLis.add(67); 
    
          // print CopyOnWriteArrayList 
          System.out.println("CopyOnWriteArrayList: " 
                                               + ArrLis); 
    
          // last occurrence of 67 from 2nd index 
          System.out.println("lastIndexOf value: " 
                            + ArrLis.lastIndexOf(67, 2)); 
      } 
  }

  輸出：

  CopyOnWriteArrayList: [32, 67, 67, 67]
  lastIndexOf value: 2
  

  示例2:

  // Java Program to illustrate the CopyOnWriteArrayList 
  // lastIndexOf() method in Java 
  import java.util.concurrent.CopyOnWriteArrayList; 
  import java.util.*; 
    
  public class GFG { 
      public static void main(String[] args) 
      { 
    
          // create object of CopyOnWriteArrayList 
          CopyOnWriteArrayList<Integer> ArrLis 
              = new CopyOnWriteArrayList<Integer>(); 
    
          // Add elements 
          ArrLis.add(32); 
          ArrLis.add(67); 
          ArrLis.add(67); 
          ArrLis.add(100); 
    
          // print CopyOnWriteArrayList 
          System.out.println("CopyOnWriteArrayList: " 
                                            + ArrLis); 
    
          // -1 is out of range, hence exception 
          System.out.println("lastIndexOf value: " 
                         + ArrLis.lastIndexOf(-1, 200)); 
      } 
  }

  輸出：

  Exception in thread “main” java.lang.ArrayIndexOutOfBoundsException: -1
  at java.util.concurrent.CopyOnWriteArrayList.lastIndexOf(CopyOnWriteArrayList.java:198)
  at java.util.concurrent.CopyOnWriteArrayList.lastIndexOf(CopyOnWriteArrayList.java:263)
  at GFG.main(GFG.java:24)

參考： https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CopyOnWriteArrayList.html#lastIndexOf-E-int-