如何将多个数据（数组）存储到Scanner的方法中？

Question

我尝试使用Scanner从主题详细信息中获取用户的多个数据。例如：用户输入数字3，然后用户必须输入主题名称，主题代码和主题费用3次，我希望将详细信息存储在一个数组中并最后显示。

修改 感谢@Ksap，代码运行正常但小问题是输入的第一个值未显示（null）仅显示最后一个输入。 截图：

到目前为止，这是主题类：

public class Subject {
public String[] subjectName;
public String[] subjectCode;
public Double[] subjectFee;

  //default constructor 
  Subject(){            
    }

 Subject(String[] subjectCode, String[] subjectName, Double[] subjectFee){
     this.subjectCode = subjectCode; 
     this.subjectName = subjectName;
     this.subjectFee = subjectFee;
   }
    //**********************************Setter Methods******************************\\
public void setSubjectCode(String[] subjectCode){
     this.subjectCode=subjectCode;
}
public void setSubjectName(String[] subjectName){
     this.subjectName=subjectName;
}
public void setSubjectFee(Double[] subjectFee){ 
     this.subjectFee=subjectFee;
}
//**********************************Getter Methods******************************\\

public String[] getSubjectCode(){ 
       return subjectCode;
}
public String[] getSubjectName(){
       return subjectName;
}
public double[] getSubjectFee(){ 
       return subjectFee;
}
}

和SubjectDriver：

public class SubjectDriver {
public static void main(String[] args) {
    int subjectAmount;
    Subject a = new Subject();
    Scanner input = new Scanner(System.in);
    System.out
        .println("Please input the amount of subjects are you resposible  for ?( Maximum 4)");
    subjectAmount = Integer.parseInt(input.nextLine());

    a.subjectName = new String[subjectAmount];
    a.subjectCode = new String[subjectAmount];
    a.subjectFee = new Double[subjectAmount];

    for (int index = 0; index < subjectAmount; index++) {
        System.out.println("enter subject name: ");
        a.subjectName[index] = input.nextLine();;

        System.out.println("enter subject code: ");
        a.subjectCode[index] = input.nextLine();

        System.out.println("enter subject fee: ");
        a.subjectFee[index] = Double.parseDouble(input.nextLine());
    }

    System.out.println("Subject name: " + Arrays.asList(a.getSubjectName())
        + "\nSubject Code: " + Arrays.asList(a.getSubjectCode()) + "\nSubject fee: "
        + Arrays.asList(a.getSubjectFee()));
}

}

你的帮助会非常明显

Answer 1

我假设您因为未初始化的数组而得到Nullpointerexception，要解决这个问题，请将这些行添加到for loop

之上

a.subjectName = new String[subjectAmount];
a.subjectCode = new String[subjectAmount];
a.subjectFee = new double[subjectAmount];

看起来Scanner因为nextInt和nextLine的混合使用而无法按预期工作，以解决此问题

将subjectAmount=input.nextInt();和subjectAmount = Integer.parseInt(input.nextLine())替换为a.subjectFee[index]=input.nextDouble() a.subjectFee[index] = Double.parseDouble(input.nextLine());

array

修改 打印array时，它将打印Arrays.asList(a.getSubjectName())的引用，如果我们要查看数组的内容，请将其转换为List并将其打印为这样 print 所以System.out.println("Subject name: " + Arrays.asList(a.getSubjectName()) + "\nSubject Code: " + Arrays.asList(a.getSubjectCode()) + "\nSubject fee: " + Arrays.asList(a.getSubjectFee())); 语句看起来像这样

subjectFee

为了您的信息，primitive double是Double数组，因此它仍会打印引用，以查看值，将其声明为public class SubjectDriver { public static void main(String[] args) { int subjectAmount; Subject a = new Subject(); Scanner input = new Scanner(System.in); System.out .println("Please input the amount of subjects are you resposible for ?( Maximum 4)"); subjectAmount = Integer.parseInt(input.nextLine()); a.subjectName = new String[subjectAmount]; a.subjectCode = new String[subjectAmount]; a.subjectFee = new Double[subjectAmount]; for (int index = 0; index < subjectAmount; index++) { System.out.println("enter subject name: "); a.subjectName[index] = input.nextLine();; System.out.println("enter subject code: "); a.subjectCode[index] = input.nextLine(); System.out.println("enter subject fee: "); a.subjectFee[index] = Double.parseDouble(input.nextLine()); } System.out.println("Subject name: " + Arrays.asList(a.getSubjectName()) + "\nSubject Code: " + Arrays.asList(a.getSubjectCode()) + "\nSubject fee: " + Arrays.asList(a.getSubjectFee())); } } 数组。

$('img').on('click', function() {
      var num = $(this).parent().attr('class').match(/\d+/)[0];
      window.num = num;
      $('.popup').fadeIn();
    });

    //Click li to update the brand and name on the page
    $('.popup li').on('click', function() {

      //Check the name and split it
      var nameComplete = $(this).attr('name');
      var Array = nameComplete.split(" ");

      //Check the first word and identify it as brand, also update on the page
      var brand = Array[0];
      $('.num-' + window.num + ' .brand').text(brand);

      //Check the rest of the array for the name and update it on the page
      var name = '';
      for(var i=1; i<Array.length ;i++) {
        name = name + Array[i] + ' ';
      }
      name = $.trim(name);

      $('.num-' + num + ' .name').text(name);

      $('.popup').fadeOut();
    });