如何基於字符串參數對對象數組執行插入排序算法？

Question

我有兩個類：Movie2 和 TestMovie2。

電影2如下：

public class Movie2 
{
    private String title;
    private int year;
    private String studio;

    Movie2(String title, int year, String studio)
    {
        this.title = title;
        this.year = year;
        this.studio = studio;
    }

    public String getTitle()
    {
        return title;
    }

    public void setTitle(String title)
    {
        this.title = title;
    }

    public int getYear()
    {
        return year;
    }

    public void setYear(int year)
    {
        this.year = year;
    }

    public String getStudio()
    {
        return studio;
    }

    public void setStudio(String studio)
    {
        this.studio = studio;
    }
}

TestMovie2如下：

public class TestMovie2 
{
    private static Movie2[] myMovies = new Movie2[10];

    private static void addMovies()
    {
        myMovies[0] = new Movie2("The Muppets Take Manhattan", 2001, "Columbia Tristar");
        myMovies[1] = new Movie2("Mulan Special Edition", 2004, "Disney");
        myMovies[2] = new Movie2("Shrek 2", 2004, "Dreamworks");
        myMovies[3] = new Movie2("The Incredibles", 2004, "Pixar");
        myMovies[4] = new Movie2("Nanny McPhee", 2006, "Universal");
        myMovies[5] = new Movie2("The Curse of the Were-Rabbit", 2006, "Aardman");
        myMovies[6] = new Movie2("Ice Age", 2002, "20th Century Fox");
        myMovies[7] = new Movie2("Lilo & Stitch", 2002, "Disney");
        myMovies[8] = new Movie2("Robots", 2005, "20th Century Fox");
        myMovies[9] = new Movie2("Monsters", 2001, "Pixar");
    }

    private static void printMovies()
    {
        for (Movie2 i : myMovies)
        {
            System.out.printf("\n%-30s%10s%30s", i.getTitle(), i.getYear(), i.getStudio());
        }
    }

    private static void sortTitles()
    {

        for (Movie2 i : myMovies)
        {
        }
    }

    public static void main (String args[])
    {
        addMovies();
        printMovies();
        sortTitles();
    }   
}

在 sortTitles() 中，我試圖創建一個算法，該算法將根據標題對對象（電影）進行排序。 不幸的是，我不能使用 Arrays.sort() 或任何類似的東西。 如果有人能給我一個字符串排序器的例子，然后逐行解釋它是如何工作的，我將不勝感激，這樣我就可以在我的項目中實現一個。

編輯：我不能使用 Arrays.sort() 因為它違反了作業的說明。

Answer 1

我相信做這個項目的目的是為了學習排序算法。 我認為給你代碼不是一個好主意，你不會從中學到很多東西。 這是一種稱為插入排序的簡單排序算法，例如： http : //www.java2novice.com/java-sorting-algorithms/insertion-sort/ 。 您可以使用 String.compareTo(anotherString) 對標題進行排序。

此外，還有許多其他不錯的排序算法可以用來提高性能，例如歸並排序和快速排序。 我可以幫你完成算法，但不會給你代碼。 祝你好運。 :)

Answer 2

選項 1：使用 Arrays.sort() 就像其他人建議的那樣，您應該能夠使用 Arrays.sort()。

現在，Arrays.sort() 對像 int[] 這樣的原始類型自動按升序排序例如：int[] numbers，然后是 Arrays.sort(numbers)。

在您的情況下，因為您想對非原始類型的電影數組進行排序。 您需要編寫一個比較器類並將其傳遞給 Arrays.sort(movies, [Your MoviesComparator Instance])。 查看此鏈接Sorting中的示例 3，它創建了一個比較器來對薪水進行排序，您想創建一個類似的比較器並按標題進行排序。 希望這會有所幫助。

選項 2：編寫自己的排序方法。 我提供了一個使用選擇排序的示例。

public class Solution {

/**
 * Movie pojo
 */
public static class Movie {
    private String title;
    private int year;
    private String studio;

    Movie(String title, int year, String studio) {
        this.title = title;
        this.year = year;
        this.studio = studio;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public int getYear() {
        return year;
    }

    public void setYear(int year) {
        this.year = year;
    }

    public String getStudio() {
        return studio;
    }

    @Override
    public String toString() {
        return "Title" +  this.getTitle() + " : " + "Year" +  this.getYear() + " : " + "Studio" + this.getStudio();
    }
}

/**
 * Sort movies on titles using selection sort
 * @param movies
 */
public static void sortMovieTitles(Movie[] movies) {
     /*Algorithm: (https://en.wikipedia.org/wiki/Selection_sort)
    Idea is to iterate & find the min element in every iteration and place it lowest index position */
    for (int i = 0; i < movies.length - 1; ++i)
    {
        int minIndex = i;
        for (int j = i + 1; j < movies.length; ++j)
        {
            if (movies[j].title.compareTo(movies[minIndex].title) < 0)
            {
                minIndex = j;
            }
        }
        Movie tempMovie = movies[i];
        movies[i] = movies[minIndex];
        movies[minIndex] = tempMovie;
    }

    //print
   for (int i = 0; i < movies.length; i++) {
       System.out.println(movies[i]);
   }
}


/**
 * Main
 * @param args input args
 */
public static void main(String[] args)

{
    Movie[] myMovies = new Movie[10];
    myMovies[0] = new Movie("The Muppets Take Manhattan", 2001, "Columbia Tristar");
    myMovies[1] = new Movie("Mulan Special Edition", 2004, "Disney");
    myMovies[2] = new Movie("Shrek 2", 2004, "Dreamworks");
    myMovies[3] = new Movie("The Incredibles", 2004, "Pixar");
    myMovies[4] = new Movie("Nanny McPhee", 2006, "Universal");
    myMovies[5] = new Movie("The Curse of the Were-Rabbit", 2006, "Aardman");
    myMovies[6] = new Movie("Ice Age", 2002, "20th Century Fox");
    myMovies[7] = new Movie("Lilo & Stitch", 2002, "Disney");
    myMovies[8] = new Movie("Robots", 2005, "20th Century Fox");
    myMovies[9] = new Movie("Monsters", 2001, "Pixar");
    sortMovieTitles(myMovies);

}

}

 //Output:
  TitleIce Age : Year2002 : Studio20th Century Fox
  TitleLilo & Stitch : Year2002 : StudioDisney
  TitleMonsters : Year2001 : StudioPixar
  TitleMulan Special Edition : Year2004 : StudioDisney
  TitleNanny McPhee : Year2006 : StudioUniversal
  TitleRobots : Year2005 : Studio20th Century Fox
  TitleShrek 2 : Year2004 : StudioDreamworks
  TitleThe Curse of the Were-Rabbit : Year2006 : StudioAardman
  TitleThe Incredibles : Year2004 : StudioPixar
  TitleThe Muppets Take Manhattan : Year2001 : StudioColumbia Tristar

Answer 3

想通了，代碼如下：

private static void sortTitles(Movie2[] input)
{   
    for (int i = 1; i < input.length; i++)
    {
        Movie2 temp;

        for (int j = i; j > 0; j--)
        {
            if (input[j].getTitle().compareTo(input[j-1].getTitle()) < 0)
            {
                temp = input[j];
                input[j] = input[j - 1];
                input[j - 1] = temp;
            }
        }
    }

    for (Movie2 i : input)
    {
        System.out.printf("\n%-30s%10s%30s", i.getTitle(), i.getYear(), i.getStudio());
    }
}

該算法改變了這一點：

The Muppets Take Manhattan          2001              Columbia Tristar
Mulan Special Edition               2004                        Disney
Shrek 2                             2004                    Dreamworks
The Incredibles                     2004                         Pixar
Nanny McPhee                        2006                     Universal
The Curse of the Were-Rabbit        2006                       Aardman
Ice Age                             2002              20th Century Fox
Lilo & Stitch                       2002                        Disney
Robots                              2005              20th Century Fox
Monsters                            2001                         Pixar

對此：

Ice Age                             2002              20th Century Fox
Lilo & Stitch                       2002                        Disney
Monsters                            2001                         Pixar
Mulan Special Edition               2004                        Disney
Nanny McPhee                        2006                     Universal
Robots                              2005              20th Century Fox
Shrek 2                             2004                    Dreamworks
The Curse of the Were-Rabbit        2006                       Aardman
The Incredibles                     2004                         Pixar
The Muppets Take Manhattan          2001              Columbia Tristar

謝謝大家的幫助！

Answer 4

好吧，閱讀您的問題后，這里是基於字符串對數組進行排序的代碼，

import java.util.Arrays;

public class InsertionSortString
{
    public static void main(String[] args)
    {
        int a, b;
        String temp;
        String[] strArray = {"Eric","David","Carol","Ben","Andy","Blair"};
        System.out.println(Arrays.toString(strArray));
        for(b = 1; b < strArray.length; b++)
        {               
            temp = strArray[b];
            a = b - 1;
            while (a >= 0)
            {
                if (temp.compareTo(strArray[a]) > 0)
                {
                    break;
                }
                strArray[a + 1] = strArray[a];
                a--;
            }
            strArray[a + 1] = temp;
            System.out.println(Arrays.toString(strArray));
        }
        System.out.println(Arrays.toString(strArray));
    }
}

同時，您可以參考下面的資源以獲取有關 Java 中插入排序的更多信息，

插入排序

插入排序示例