java - Java中可以使用哪个实用程序类来存储和应用排序

Question

我有点困惑哪些实用程序类可以用于解决此类问题:
我有一个文件 Movies.txt，其中包含以下信息:Id、Name、Director、Rating。评级可能存在也可能不存在。

示例:

1,ABC,Mr. xyz,4.5
3,GHI,Mr. mno
2,DEF,Ms. stu,3

我需要读取此文件并将其存储到内存中，然后应用按评级和名称排序，然后稍后写入该文件。 在这种情况下，哪个实用程序类最能帮助我，这样如果可能的话，可以轻松地做到这一点。没有更多文件可供使用。

Answer 1

首先定义 Object描述了“电影”的基本属性。让您的生活更轻松，implement Comparable<Movie>可能是个好主意直接。

public class Movie implements Comparable<Movie> {

    private int id;
    private String name;
    private String directory;
    private double rating;

    public Movie(int id, String name, String directory, double rating) {
        this.id = id;
        this.name = name;
        this.directory = directory;
        this.rating = rating;
    }

    public int getId() {
        return id;
    }

    public String getDirectory() {
        return directory;
    }

    public String getName() {
        return name;
    }

    public double getRating() {
        return rating;
    }

    @Override
    public int compareTo(Movie o) {
        int diff = (int) asInt(getRating()) - asInt(o.getRating());
        if (diff == 0) {
            diff = getName().compareTo(name);
        }
        return diff;
    }

    protected int asInt(double value) {
        String text = Double.toString(value);
        text = text.replaceAll("\\.", "");
        return Integer.parseInt(text);
    }

    @Override
    public String toString() {
        return getId() + ", " + getName() + ", " + getDirectory() + ", " + getRating();
    }

}

创建 List保存传入的电影

List<Movie> movies = new ArrayList<Movie>(25);

读取 的内容并将每一行解析为单独的属性元素(我将留给您)，添加每个新创建的 Movie到列表...

movies.add(new Movie(...));

使用Collections.sort(movies)对它们进行排序...

例如...

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class SortExample {

    public static void main(String[] args) {
        List<Movie> movies = new ArrayList<Movie>(5);
        movies.add(new Movie(1, "ABC", "Mr. xyz", 4.5));
        movies.add(new Movie(2, "GHI", "Mr. mno", 0));
        movies.add(new Movie(3, "DEF", "Ms. stu", 3));
        movies.add(new Movie(4, "AT1", "Mr. T", 3));

        System.out.println("Before....");
        for (Movie movie : movies) {
            System.out.println(movie);
        }

        Collections.sort(movies);

        System.out.println("After....");
        for (Movie movie : movies) {
            System.out.println(movie);
        }

    }

    public static class Movie implements Comparable<Movie> {

        private int id;
        private String name;
        private String directory;
        private double rating;

        public Movie(int id, String name, String directory, double rating) {
            this.id = id;
            this.name = name;
            this.directory = directory;
            this.rating = rating;
        }

        public int getId() {
            return id;
        }

        public String getDirectory() {
            return directory;
        }

        public String getName() {
            return name;
        }

        public double getRating() {
            return rating;
        }

        @Override
        public int compareTo(Movie o) {
            int diff = (int) asInt(getRating()) - asInt(o.getRating());
            if (diff == 0) {
                diff = getName().compareTo(name);
            }
            return diff;
        }

        protected int asInt(double value) {
            String text = Double.toString(value);
            text = text.replaceAll("\\.", "");
            return Integer.parseInt(text);
        }

        @Override
        public String toString() {
            return getId() + ", " + getName() + ", " + getDirectory() + ", " + getRating();
        }

    }

}