Java CopyOnWriteArrayList indexOf() 方法

2025 年 3 月 21 日 | 阅读 2 分钟

java CopyOnWriteArrayList 类的 indexOf() 方法在列表中从指定位置 index 或之后开始搜索，并返回指定元素首次出现的索引。如果未找到该元素，则此方法将返回 -1。

语法

参数

e ? 要搜索的元素

index ? 开始搜索的索引

返回值

此方法返回列表中从指定位置 index 开始的元素首次出现的索引。如果未找到该元素，则此方法将返回 -1。

示例 1

import java.util.concurrent.CopyOnWriteArrayList;

public class CopyOnWriteArrayListIndexOfExample1{
	
	public static void main(String[] args) {
		//Initializing CopyOnWriteArrayList of Integers
		CopyOnWriteArrayList<Integer>numbers = new CopyOnWriteArrayList<>(new Integer[] {1,2,1,4,5,3,3,3});
		//Prints index of the first occurrence of the element in this list at position index or later in the list and  -1 if the element is not found.
		System.out.println("Index of 3 is : " + numbers.indexOf(3, 1));
		
			}	
	}

输出

Index of 3 is : 5

示例 2

import java.util.concurrent.CopyOnWriteArrayList;

public class CopyOnWriteArrayListIndexOfExample2{
	
	public static void main(String[] args) {
		//Initializing CopyOnWriteArrayList of Integers
		CopyOnWriteArrayList<Integer>numbers = new CopyOnWriteArrayList<>(new Integer[] {1,2,1,4,5,3,3,3});
		//Prints index of the first occurrence of the element in this list at position index or later in the list and  -1 if the element is not found.
		System.out.println("Index of 9 is : " + numbers.indexOf(9, 1));
				}
		}

输出

Index of 9 is : -1

示例 3

import java.util.concurrent.CopyOnWriteArrayList;

public class CopyOnWriteArrayListIndexOfExample3{
	
	public static void main(String[] args) {
		//Initializing CopyOnWriteArrayList of Strings
		CopyOnWriteArrayList<String>listOfNames = new CopyOnWriteArrayList<>(new String[] {"Tom","Harry","John","John"});
		//Prints index of the first occurrence of the element in this list at position index or later in the list and  -1 if the element is not found.
		System.out.println("Index of John is : " + listOfNames.indexOf("John", 1));
		
			}
		}

输出

Index of John is : 2

示例 4

import java.util.concurrent.CopyOnWriteArrayList;

public class CopyOnWriteArrayListIndexOfExample4{
	
	public static void main(String[] args) {
		//Initializing CopyOnWriteArrayList of Strings
		CopyOnWriteArrayList<String>listOfNames = new CopyOnWriteArrayList<>(new String[] {"Tom","Harry","John","John"});
		//Prints index of the first occurrence of the element in this list at position index or later in the list and  -1 if the element is not found.
		System.out.println("Index of Jerry is : " + listOfNames.indexOf("Jerry", 1));
		
			}
	}

输出

Index of Jerry is : -1

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Java CopyOnWriteArrayList indexOf() 方法

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Java CopyOnWriteArrayList indexOf() 方法

语法

参数

返回值

示例 1

示例 2

示例 3

示例 4

相关帖子

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