java向数组中增加新元素_用Java中的新元素替换List的给定索引处的元素

小咪咪 2023-03-05 04:29 9阅读 0赞

java向数组中增加新元素

**Given a list of the integers and we have to replace it an element from specified index with a new element in java.**

**给定一个整数列表，我们必须用Java中的新元素将其替换为指定索引中的一个元素。**

To **replace an element in the list** \- we use List.set() method.

要**替换列表中的元素** \-我们使用List.set()方法。

## List.set()方法 **(**List.set() method**)** ##

List.set() method replaces an existing element at given index with new element and returns the old object/element.

List.set()方法将给定索引处的现有元素替换为新元素，并返回旧对象/元素。

**Syntax:**

**句法：**

Object List.set(index, new_object);

**Example:**

**例：**

Input:
        List = [10, 20, 30, 40, 50]
        Index =1 
        new_element = 1000
    
        Output:
        Updated list =[10, 1000, 30, 40, 50]

**Program:**

**程序：**

import java.util.*;
    public class ListExample {
        
    	public static void main (String[] args) 
    	{
        
    		//creating a list of integers
    		List<Integer> int_list = new ArrayList<Integer> ();
    
    		//adding some of the elements 
    		int_list.add (10) ;
    		int_list.add (20) ;
    		int_list.add (30) ;
    		int_list.add (40) ;
    		int_list.add (50) ;
    
    		//replace elements
    		int old_ele, new_ele, index;
    		index =0; new_ele=12;
    		old_ele = int_list.set (index, new_ele);
    		System.out.println (old_ele+" is replace with "+new_ele);
    
    		index =2; new_ele=24;
    		old_ele = int_list.set (index, new_ele);
    		System.out.println (old_ele+" is replace with "+new_ele);
    
    		//printing updated list 
    		System.out.println ("updated list: " + int_list);
    	}
    };

**Output**

**输出量**

10 is replace with 12
    30 is replace with 24
    updated list: [12, 20, 24, 40, 50]

### 另一个示例：将EVEN索引的所有元素替换为0，将ODD索引替换为1 **(**Another Example: Replace all elements of EVEN indexes with 0 and ODD indexes by 1 **)** ###

**Example:**

**例：**

Input:
        List = [10, 20, 30, 40, 50]
    
        Output:
        Updated list =[0, 1, 0, 1, 0]

**Program:**

**程序：**

import java.util.*;
    public class ListExample {
        
    	public static void main (String[] args) 
    	{
        
    		//creating a list of integers
    		List<Integer> int_list = new ArrayList<Integer> ();
    		
    		//adding some of the elements 
    		int_list.add (10) ;
    		int_list.add (20) ;
    		int_list.add (30) ;
    		int_list.add (40) ;
    		int_list.add (50) ;
    		
    		System.out.println ("len: " + int_list.size ());
    		//replace elements 
    		for (int i=0; i<int_list.size(); i++) {
        
    			if (i%2==0)
    				int_list.set (i, 0);
    			else
    				int_list.set (i, 1);		
    		}
    		
    		//printing updated list 
    		System.out.println ("updated list: " + int_list);
    	}
    };

**Output**

**输出量**

len: 5
    updated list: [0, 1, 0, 1, 0]

> 翻译自: [https://www.includehelp.com/java-programs/replace-an-element-at-given-index-of-a-list-with-new-element-in-java.aspx][https_www.includehelp.com_java-programs_replace-an-element-at-given-index-of-a-list-with-new-element-in-java.aspx]

java向数组中增加新元素

[https_www.includehelp.com_java-programs_replace-an-element-at-given-index-of-a-list-with-new-element-in-java.aspx]: https://www.includehelp.com/java-programs/replace-an-element-at-given-index-of-a-list-with-new-element-in-java.aspx