Question

我需要创建一个方法来搜索String数组是否在数组中存在specfic字符并返回该字符出现的出现次数的整数，我已查看其他帖子尝试自己解决但是他们都是int而不是String的数组

我有另一个类名，因此数组名称为Name。

public class Reg {

    //Fields
    private ArrayList<Name> Name; 


    //Constructors
    public Reg() {
        Name = new ArrayList<>();
    }

    //Methods

    public int CountCharacterOccurrences (Char character){

    }
}

名称等级：

public class Name implements Comparable<Name> {

    //Fields
    private String firstName;
    private String familyName;


    //Constructors
    public Name() {
        firstName = "";
        familyName = "";
    }

    public Name(String firstName, String familyName) {
        this.firstName = firstName;
        this.familyName = familyName;
    }


    //Methods
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public void setFamilyName(String familyName) {
        this.familyName = familyName;
    }

    public String getFirstName() {
        return firstName;
    }

    public String getFamilyName() {
        return familyName;
    }

    public String getFullName() {
        if (firstName.equals("") && familyName.equals("")) {
            return "";
        } else {
            return firstName + " " + familyName;
        }
    }

    @Override
    public String toString() {
        return "Name:[firstName=" + firstName + ", familyName=" + familyName + "]";
    }
}

如何添加一个接受char参数的CountCharacterOccurences方法，并返回一个表示发生次数的int。

Answer 1

也许这就是你的意思：

class Reg{
    private ArrayList<Name> names;

    public Reg() {
        names = new ArrayList<>();
    }

    public int countFirstNameOccurrences(char c) {
        return names.stream()            // get Stream<Name>
                .map(Name::getFirstName) // convert Stream<Name> to Stream<String> using Name's firstName
                .mapToInt(s -> s.length() - s.replace(String.valueOf(c), "").length()) // calculate every occurrence c in each firstName and get an IntStream
                .sum();                  // sum all the values
    }

    public static void main(String[] args) {
        Reg reg = new Reg();
        reg.names.add(new Name("John", "Doe"));
        reg.names.add(new Name("Johnny ", "Doe"));
        reg.names.add(new Name("Richard", "Roe"));
        reg.names.add(new Name("James", "Roe"));
        reg.names.add(new Name("Jane", "Roe"));

        System.out.println(reg.countFirstNameOccurrences('J'));
    }
}

输出：

4

因为名单中的名字中有4个J（John，Johnny，James和Jane）

创建方法来计算数组中char类型的出现次数

1 个答案: