Question

import java.util.Scanner;

public class userInputTest {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        for(int i = 0; i>-1; i=i+1){

            String[] giveMeAString = new String[i+1];
            String x = sc.next();

            giveMeAString[i]=x;

            if(i>=0){
                if (giveMeAString[i].length() < giveMeAString[i-1].length()){
                    System.out.println("The string is shorter than previous string!");
                    break;}
            }

        }

    }   
}

我想循环，直到当前用户输入长度小于之前的用户输入长度。

经过多次尝试后，我暂时没有解决它。

我做错了什么？我想使用Array，因为我还想稍后打印用户输入。

我现在唯一的问题是使编写的代码有效。

Answer 1

需要注意的事项：

您每次都要重置数组，因为声明（内存分配）在＆＃39;之内。环
数组大小（i + 1）将在您尝试更多次数时分配大量内存
giveMeAString [i-1]：i = 1 - 这应该是for（）的起点。否则，您将获得arrayIndexOutOfBound异常，因为当i = 0时您将访问giveMeAString [-1]。这是不存在的数组位置/元素索引。
如果你想比较2个连续的字符串长度，你需要确保在循环的第一次迭代中，你至少填充了2个字符串（或者检查你是否在第一次迭代，然后继续循环以添加第二次字符串没有进一步。）

更正后的代码是：

Scanner sc = new Scanner(System.in);

        //arrays are alaways static memory allocation constructs. First input should always be the array size. If this is not known
        //ahead of time, use List, ArrayList etc.
        int a;
        System.out.println("Enter Array size in number: ");
        a = sc.nextInt();
        String[] giveMeAString = new String[a];
        String x;

        //updaing the loop initialization and condition
        for(int i = 1; i>0; i=i+1){

            //should NOT be creating array every time. Strings are immutable and hence costly w.r.t. memory/responseTime.
            //Besides, i didn't understand the logic of creating array of String of size (i+1).
            //instead, consider using resizable list (ArrayList etc). Below line is resetting your previously input values in giveMeAString[]
            //String[] giveMeAString = new String[i+1];


            if (i == 1) {
                //adding first input to array's first index. Without this, we would get NPE. One time execution.
                x = sc.next();
                giveMeAString[i - 1] = x;
            }

            //adding next input to array's next index
            x = sc.next();
            giveMeAString[i]= x;

            if(i>=0){
                if (giveMeAString[i].length() < giveMeAString[i-1].length()){
                    System.out.println("The string is shorter than previous string!");
                    break;
                }
            }

        }

Answer 2

与之前的答案类似，但使用ArrayList实现，如果不应限制数组大小。

    Scanner scn = new Scanner( System.in );
    List<String> strList = new ArrayList<>();

    /*
     * First clase to allow logic receive at least 1 input without performing the check.
     * Next clause to check if current input length is greater than previous input length, continue receiving input
     */
    while ( strList.size() < 2 || strList.get( strList.size() - 1  ).length() 
            >= strList.get(strList.size() - 2 ).length() )
    {
        System.out.println(" Enter new String: " );
        strList.add( scn.next() );
    }

    System.out.println( "Previous String is shorter." );
    scn.close();

    System.out.println(Arrays.toString( strList.toArray() ));

更新，使用数组实现。

Scanner scn = new Scanner( System.in );
String [] strArray = new String[0];

/*
 * First clause to allow logic receive at least 1 input without
 * performing the check. Next clause to check if current input length is
 * greater than previous input length, continue receiving input
 */
while ( strArray.length < 2
    || strArray[strArray.length - 1].length() >= strArray[strArray.length -2].length() )
{
    String[] tempArr = new String[strArray.length + 1];
    for(int i = 0; i < strArray.length; i++){
        tempArr[i] = strArray[i];
    }
    strArray = tempArr;
    System.out.println( " Enter new String: " );
    strArray[strArray.length - 1] = scn.next();
}

System.out.println( "Previous String is shorter." );
scn.close();

System.out.println( Arrays.toString( strArray ) );

循环直到用户输入长度小于或等于先前的用户输入

2 个答案: