阵列无法正确打印出所有答案

Question

Im making a main method that creates an array to keep track of some presidential candidates. The user inputs the number of candidates they want, and then inputs the candidates names they want in the election, then prints out the candidates with what position they were put in (1, 2, 3 not 0, 1, 2). Right now the method only prints out the 2nd and 3rd names, and will not print the 1st name.

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

Here, the following for loop is the problem

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

What happens is, even though you feel like you are entering 5 candidates, you have actually stored 4 in the array. To resolve this, just interchange the lines as,

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

Answer 2

In your first for loop you are reading numCandidates -1 values instead of numCandidates , so you could just swap the lines inside your for loop:

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

I guess you can even remove the variable newString and just use the variable 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

looping problem,the code must be as follows.

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

This is a reoccurring problem. nextInt() stops when it encounters a non-digit, and it leaves that non-digit in the input stream.

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

If your input stream consists of:

3
Alice
Bob
Carol

It actually looks to the Scanner like:

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

After nextInt() is called (which returns 3 , as expected), the input stream is left with:

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

When nextLine() is called, all the characters up to the next newline character are read, and returned, and the newline is consumed. Thus, "" is returned for newCandidate , not "Alice" !

If done in a loop:

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

The 3 candidates returned are:

• ""
• "Alice"
• "Bob"

The take home is to remember to call nextLine() to remove trailing newline characters after a line has been partially read by other nextXXX() calls.

Answer 5

First you have some unnecessary string variables. Try this out, at least it works fine on my machine!

        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());

EDIT : Samples

Assuming numCandidates = 3 and names entered are Will Linger, Andy Putty, Jimmy , the output should be " The candidates names are: 1) Will Linger 2) Andy Putty 3) Jimmy "