Java 中的 copy onwriterarraylist last indexof()方法
原文:https://www . geesforgeks . org/copy onwriterarraylist-last indexof-method-in-Java/
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The lastIndexOf(Object o) method of CopyOnWriteArrayList returns the last occurrence of the element passed in the list. It returns -1 if the element is not present in the list.
语法:
java public int lastIndexOf(Object o)
参数:该函数接受一个参数 o ,该参数的最后一次出现将被返回。
返回值:函数返回元素的最后一次出现。如果该元素不在列表中,则返回-1。
以下程序说明了上述功能:
程序 1:
```java // 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 ArrLis = new CopyOnWriteArrayList();
// 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)); } } ```
Output:
```java CopyOnWriteArrayList: [32, 67, 67, 100] lastIndexOf value: 2
```
程序 2:
```java // 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 ArrLis = new CopyOnWriteArrayList();
// 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)); } } ```
Output:
```java CopyOnWriteArrayList: [32, 67, 67, 100] lastIndexOf value: -1
```
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The lastIndexOf(E e, int index) method of CopyOnWriteArrayList returns the last occurrence of the element passed in the list after position index. It returns -1 if the element is not present in the list.
语法:
java public int lastIndexOf(E e, int index)
参数:该函数接受两个参数,如下所述:
- 索引:指定从中搜索事件的索引。
- e :指定最后一次从位置索引出现的元素将被返回。
返回值:函数返回位置索引后元素的最后一次出现。如果该元素不在列表中,则返回-1。
异常:如果指定的指数为负,该函数将抛出指数。
以下程序说明了上述功能:
程序 1:
```java // 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 ArrLis = new CopyOnWriteArrayList();
// 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)); } } ```
Output:
```java CopyOnWriteArrayList: [32, 67, 67, 67] lastIndexOf value: 2
```
程序 2:
```java // 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 ArrLis = new CopyOnWriteArrayList();
// 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)); } } ```
输出:
线程“main”Java . lang . arrayindexoutofboundsexception:-1 在 Java . util . concurrent . copy onwriterarraylist . last indexof(copy onwriterarraylist . Java:198) 在 Java . util . concurrent . copy onwriterarraylist . last indexof(copy onwriterarraylist . Java:263) 在 GFG.main(GFG.java:24)
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