Question

所以我必须创建一个Java程序，用户在其中说明要输入多少个值，在数组中输入多个值，打印数组。然后我必须反转数组中的元素（不反转打印或创建一个新数组），然后再次打印这些值。这是我的以下代码：

package reversearray;

import java.util.*;

public class Swap_main {

    /**
     * Taylor Marino
     */
    public static void main(String[] args) {
        int arraysize = 0, junk, junk2;
        Scanner reader = new Scanner(System.in);
        System.out.println("How many values are you going to enter?");
        arraysize = reader.nextInt();
        int[] array = new int[arraysize];
        System.out.println("You will now be asked to enter your values, one at a time");
        for(int counter = 0; counter < arraysize; counter++){
            System.out.println("Enter next value");
            array[counter] = reader.nextInt();
        }
        System.out.println("The values you entered are: ");
        for(int counter2 = 0; counter2 < arraysize; counter2++)
            System.out.print(array[counter2] + ", ");
        for(int counter3 = 0, counter4 = arraysize; counter3 != counter4; counter3++, counter4--){
            junk = array[counter3];
            junk2 = array[counter4];
            array[counter4] = junk;
            array[counter3] = junk2;
        }
        System.out.println("The values you entered are (in reverse order): ");
        for(int counter5 = 0; counter5 < arraysize; counter5++)
            System.out.print(array[counter5] + ", ");
    }

}

但是我在这个循环中收到错误：

        for(int counter3 = 0, counter4 = arraysize; counter3 != counter4; counter3++, counter4--){
            junk = array[counter3];
            junk2 = array[counter4];
            array[counter4] = junk;
            array[counter3] = junk2;
        }

我不知道这里有什么问题，但它说array[counter4] = junk;出错了我做错了什么？

Answer 1

由于数组从0索引到长度为1，因此会给出一个ArrayOutOfBoundsException。从counter4 = arraysize-1开始。

编辑：另外，你应该改变

counter3 != counter4

到

counter3 < counter4

因为在奇数长度的数组上，第一个条件永远不会给你真实。

Answer 2

更改

for(int counter3 = 0, counter4 = arraysize

到

for(int counter3 = 0, counter4 = arraysize-1

Answer 3

尝试

for(int counter3 = 0, counter4 = arraysize -1 ; counter3 < counter4 ; counter3++, counter4--){

有效。例外消失了。

Answer 4

可能稍微简洁一些，只使用一个循环变量

int maxIndex = array.length-1; // Zero based
int midIndex = (maxIndex/2);   // only swap half, otherwise will swap back to original
for(int counter3 = 0; counter3 <= midIndex; counter3++){
    junk = array[counter3];
    array[counter3] = array[maxIndex-counter3];
    array[maxIndex-counter3] = junk;
}

在int数组java中重新排列int值

4 个答案: