如何在Java中打印出数组的偶数索引？

Question

我应该编写一个程序，使用for循环打印出我的数组的偶数索引。例如，如果我创建了一个包含10个数字的数组，它将具有0-9的索引，因此在这种情况下，我会打印索引2,4,6和8中的数字。这是我迄今为止所写的，但它不起作用。请注意，我不打印出数组的偶数。我想要的只是偶数索引。

例子我输入下面的数组：3,7,5,5,5,7,7,9,9,3

程序输出：

5 // (the number at index 2) 
5 // (the number at index 4) 
7 // (the number at index 6) 
9 // (the number at index 8) 

我的代码：

public class Arrayevenindex 
{ 
    public static void main(String[] args) 
    { 
     int number; // variable that will represent how many elements the user wants the array to have 

     Scanner key = new Scanner(System.in); 

     System.out.println(" How many elements would you like your array to have"); 
     number = key.nextInt(); 
     int [] array = new int [number]; 

     // let the user enter the values of the array. 
     for (int index = 0; index < number; index ++) 
     { 
      System.out.print(" Value" + (index+1) + " :"); 
      array[index] = key.nextInt(); 
     } 
     // Print out the even indexes 
     System.out.println("/nI am now going to print out the even indexes"); 
     for (int index = 0; index < array.length; index ++) 
     { 
      if (array[number+1]%2==0) 
       System.out.print(array[number]); 
     } 
    } 
} 

Answer 1

你可以改变你的for循环，摆脱内部IF的...

for(int index = 0; index < array.length; index += 2) { 
    System.out.println(array[index]); 
} 

Answer 2

就绝对相同的使用Java的东西8 Stream API

Integer[] ints = {0,1,2,3,4,5,6,7,8,9}; 
IntStream.range(0, ints.length).filter(i -> i % 2 == 0).forEach(i -> System.out.println(ints[i])); 

Answer 3

我认为这将是足够

// For loop to search array 
for (int i = 0; i < array.length; i++) { 

    // If to validate that the index is divisible by 2 
    if (i % 2 == 0) { 
    System.out.print(array[i]); 
    } 
} 

Answer 4

这是我做的，它的工作原理：还我没有打印出指数[0]因为在技术上它甚至不是这样，为什么我在2开始for循环。你的帖子确实帮了我很多。我也感谢所有花时间发布答案的人。

import java.util.Scanner; 



public class Arrayevenindex 
{ 
public static void main(String[] args) 
{ 
    int number; // variable that will represent how many elements the user wants the array to have 


    Scanner key = new Scanner(System.in); 

    System.out.println(" How many elements would you like your array to have"); 
    number = key.nextInt(); 
    int [] array = new int [number]; 


// let the user enter the values of the array. 
for (int index = 0; index < number; index ++) 
{ 
System.out.print(" Value" + (index+1) + " :"); 
array[index] = key.nextInt(); 



} 
// Print out the even indexes 
System.out.println("/nI am now going to print out the even indexes"); 
for (int index = 2; index < array.length; index +=2) 
{ 

    System.out.print(array[index] + " "); 



} 

    } 

}