阵列无法正确打印出所有答案

Question

我正在制作一种主要方法，该方法创建一个数组来跟踪某些总统候选人。 用户输入他们想要的候选人数量，然后输入他们想要的选举候选人名称，然后打印出候选人所处的位置（1、2、3而不是0、1、2）。 现在，该方法仅打印出第二和第三名称，而不会打印出第一名称。

public class RunElection


/**
 * 
 */
public static void main(String[] args)
{
    Scanner scan = new Scanner(System.in);
    System.out.println("Please input the number of candidates you would like in this election.");  
    int numCandidates = scan.nextInt();
    while (numCandidates <= 0) {
        System.out.println("Please input a number that is greater than zero.");   
        numCandidates = scan.nextInt(); 
    } 
    String[] candidates;
    candidates = new String[numCandidates];  

    System.out.println("Please input the name of the candidates in the election."); 
    String newCandidate = scan.nextLine(); 
    String newString = " "; 
    String finalString = " "; 

    for (int i = 0; i<candidates.length; i++) {
        candidates[i] = newCandidate; 
        newCandidate = scan.nextLine();    
    }

    for(int i = 0; i<candidates.length; i++) {
        newString = "the candidates names are: " + " " + i + " ) " + candidates[i];
        finalString = finalString+ newString;  
    }
    System.out.println(finalString); 


}

Answer 1

在这里，下面的for循环就是问题所在

for (int i = 0; i<candidates.length; i++) {
        candidates[i] = newCandidate; 
        newCandidate = scan.nextLine();    
}

发生的是，即使您感觉要输入5个候选者，您实际上已经在阵列中存储了4个。 要解决此问题，只需将行交换为

for (int i = 0; i<candidates.length; i++) {
    newCandidate = scan.nextLine();
    candidates[i] = newCandidate;     
}

Answer 2

在您的第一个for循环中，您正在读取numCandidates -1值，而不是numCandidates ，因此您可以在for循环内交换行：

for (int i = 0; i<candidates.length; i++) {
    newCandidate = scan.nextLine();
    candidates[i] = newCandidate;     
}

我想你甚至可以删除变量newString ，只是使用的变量finalString ：

import java.util.Scanner;

public class RunElection {
  public static void main(String[] args) {
      Scanner scan = new Scanner(System.in);
      System.out.println("Please input the number of candidates you would like in this election.");
      int numCandidates = scan.nextInt();

      while (numCandidates <= 0) {
          System.out.println("Please input a number that is greater than zero.");
          numCandidates = scan.nextInt();
      }

      String[] candidates;
      candidates = new String[numCandidates];

      System.out.println("Please input the name of the candidates in the election.");
      String newCandidate = scan.nextLine();
      String finalString = "";

      for (int i = 0; i<candidates.length; i++) {
          newCandidate = scan.nextLine();
          candidates[i] = newCandidate;
      }

      for(int i = 0; i<candidates.length; i++) {
          finalString += "The candidates names are: " + " " + i + ") " + candidates[i] + "\n";
      }

      System.out.println(finalString);
    }
}

Answer 3

循环问题，代码必须如下。

public class RunElection



public static void main(String[] args)
{
    Scanner scan = new Scanner(System.in);
    System.out.println("Please input the number of candidates you would like in this election.");  
    int numCandidates = scan.nextInt();
    while (numCandidates <= 0) {
        System.out.println("Please input a number that is greater than zero.");   
        numCandidates = scan.nextInt(); 
    } 
    String[] candidates;
    candidates = new String[numCandidates];  

    System.out.println("Please input the name of the candidates in the election."); 

    String newString = " "; 
    String finalString = " "; 

    for (int i = 0; i<candidates.length; i++) {
newCandidate = scan.nextLine();  
            candidates[i] = newCandidate; 

    }

    for(int i = 0; i<candidates.length; i++) {
        newString = "the candidates names are: " + " " + i + " ) " + candidates[i];
        finalString = finalString+ newString;  
    }
    System.out.println(finalString); 


}

Answer 4

这是一个经常发生的问题。 当nextInt()遇到一个非数字时，它将停止，并将该非数字留在输入流中。

int numCandidates = scan.nextInt();
String newCandidate = scan.nextLine();

如果您的输入流包括：

3
Alice
Bob
Carol

扫描仪实际上看起来像：

3 \n A l i c e \n B o b \n C a r o l \n

调用nextInt() （按预期返回3 ）后，输入流将保留：

\n A l i c e \n B o b \n C a r o l \n

调用nextLine() ，读取并返回直到下一个换行符的所有字符，并且消耗了换行符。 因此， ""则返回newCandidate ，而不是"Alice" ！

如果循环完成：

int numCandidates = scan.nextInt();
for(int i=0; i<numCandidates; i++) {
    String newCandidate = scan.nextLine();
    //...
}

返回的3名候选人为：

• “”
• “爱丽丝”
• “鲍勃”

带回家的地方是记住在其他nextXXX()调用已部分读取一行后，调用nextLine()删除尾随的换行符。

Answer 5

首先，您有一些不必要的字符串变量。 试试看，至少在我的机器上可以正常工作！

        String[] candidates = new String [numCandidates];
        System.out.println("Please input the name of the candidates in the election, one on each line"); 
        Scanner scan = new Scanner(System.in);
        StringBuilder finalCandidates = new StringBuilder(); 

        for (int i = 0; i < candidates.length; i++) {
            candidates[i] = scan.nextLine(); 
        }
        scan.close();

        for(int i = 0; i < candidates.length; i++) {
            finalCandidates.append(i + 1 + ") " + candidates[i] + " ");
        }

        System.out.println("The candidates names are: " + " " + finalCandidates.toString());

编辑 ：样本

假设numCandidates = 3并且输入的名称是Will Linger, Andy Putty, Jimmy ，则输出应为“ The candidates names are: 1) Will Linger 2) Andy Putty 3) Jimmy ”