在binarySearch中傳遞參數

Question

我有三個類;包含我的主要方法的Movies/tester類。一個DVDCollection類，它對數組進行增量排序，並具有一個具有Constuctor方法並覆蓋compareTo的DVD Comparable Class。我們的導師要求我們使用電影/測試人員類的主要方法來搜索特定導演的收藏。我完全卡住了，因爲我認爲我需要傳遞一個Comparable Array和一個Comparable目標，但是指令說我只是傳遞一個String參數。我收到了無效的數據類型。任何人都在幫助有需要的學生。

public class Movies 
{ 
    public static void main (String[] args) 
    { 
    Comparable found; 


     DVDCollection movies = new DVDCollection(); 

     movies.addDVD ("The Godfather", "Francis Ford Coppola", 1972, 24.95, true); 
     movies.addDVD ("District 9", "Neill Blonkamp", 2009, 19.95, false); 
     movies.addDVD ("Iron Man", "Jon Favreau", 2008, 15.95, false); 
     movies.addDVD ("All About Eve", "Joseph Makiewicz", 1950, 17.50, false); 
     movies.addDVD ("The Matrix", "Andy & Lana Wachowski", 1999, 19.95, true); 

     System.out.println (movies); 

     movies.addDVD ("Iron Man 2", "Jon Favreau", 2010, 22.99, false); 
     movies.addDVD ("Casablanca", "Michael Curtiz", 1942, 19.95, false); 

     System.out.println (movies); 

     Comparable target = ("Jon Favreau"); 
     found = DVD.searchForDVD(target); 
     if (found != null) 
      System.out.println ("Found: " + index); 
     else 
      System.out.println ("The director was not found."); 


     Comparable target = ("John Smith"); 
     found = DVD.searchForDVD(target); 
     DVD.searchForDVD(target); 
     if (found != null) 
      System.out.println ("Found: " + index); 
     else 
      System.out.println ("The director was not found."); 

    } 
} 

import java.text.NumberFormat; 

public class DVDCollection 
{ 
    private DVD[] list; 
    private int count; 
    private double totalCost; 

    public DVDCollection() 
    { 
     list = new DVD[100]; 
     count = 0; 
     totalCost = 0; 
    } 
    public void addDVD (String title, String director, int year, double cost, boolean bluray) 
    { 
     list[count] = new DVD (title, director, year, cost, bluray); 
     for (int index = 1; index < list.length; index++) 
     { 

      DVD key = list[count]; 
      int position = count; 

      while (position > 0 && key.compareTo(list[position-1]) < 0) 
      { 
       list[position] = list[position-1]; 
       position--; 
      } 
      list[position] = key; 

     } 
     totalCost += cost; 
     count++; 
    } 

    public String toString() 
    { 
     NumberFormat fmt = NumberFormat.getCurrencyInstance(); 

     String report = "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n"; 
     report += "My DVD Collection\n\n"; 

     report += "Number of DVDs: " + count + "\n"; 
     report += "Total cost: " + fmt.format(totalCost) + "\n"; 
     report += "Average cost: " + fmt.format(totalCost/count); 

     report += "\n\nDVD List:\n\n"; 

     for (int dvd = 0; dvd < count; dvd++) 
     report += list[dvd].toString() + "\n"; 

     return report; 
    } 

} 

import java.text.NumberFormat; 
public class DVD implements Comparable 
{ 
    private String title, director; 
    private int year; 
    private double cost; 
    private boolean bluray; 

    public DVD (String title, String director, int year, double cost, boolean bluray) 
    { 
     this.title = title; 
     this.director = director; 
     this.year = year; 
     this.cost = cost; 
     this.bluray = bluray; 
    } 
    public String toString() 
    { 
     NumberFormat fmt = NumberFormat.getCurrencyInstance(); 

     String description; 

     description = fmt.format(cost) + "\t" + year + "\t"; 
     description += title + "\t" + director; 

     if (bluray) 
     description += "\t" + "Blu-Ray"; 

     return description; 
    } 

    public String getDirector() 
    { 
     return director; 
    } 
    public int compareTo (Object list) 
    { 
     int result; 

     String otherDirector = ((DVD)list).getDirector(); 
     result = director.compareTo(otherDirector); 

     return result; 
    } 

    public static int searchForDVD (String director) 
    { 
     int index = 0, min = 0, max = 7, mid=0; 
     boolean found = false; 
     while (!found && min <= max) 
     { 
      mid = (min+max)/2; 
      if (director.compareTo(director) == 0) 
      return index; 
      else 
       if (director.compareTo(director) < 0) 
        max = mid - 1; 
       else 
        min = mid + 1; 
     } 
     if (found) 
     return index; 
     else 
     return -1; 
    }  

} 

我們需要返回目標「director」的數組位置索引或返回-1。

Answer 1

我希望下面的代碼是你所期望的，只是試試這個作爲一個單獨的程序&執行。

public class Movies 
{ 
    public static DVDCollection movies; 
    public static void main (String[] args) 
    { 
    Comparable found; 
    int index; 

    movies= new DVDCollection(); 

    movies.addDVD ("The Godfather", "Francis Ford Coppola", 1972, 24.95, true); 
    movies.addDVD ("District 9", "Neill Blonkamp", 2009, 19.95, false); 
    movies.addDVD ("Iron Man", "Jon Favreau", 2008, 15.95, false); 
    movies.addDVD ("All About Eve", "Joseph Makiewicz", 1950, 17.50, false); 
    movies.addDVD ("The Matrix", "Andy & Lana Wachowski", 1999, 19.95, true); 

    System.out.println (movies); 

    movies.addDVD ("Iron Man 2", "Jon Favreau", 2010, 22.99, false); 
    movies.addDVD ("Casablanca", "Michael Curtiz", 1942, 19.95, false); 

    System.out.println (movies); 

    Comparable target = ("Jon Favreau"); 
    System.out.println("Target: "+target.toString()); 
    found = DVD.searchForDVD(target.toString()); 
    index=Integer.parseInt(found.toString()); 

    System.out.println ("Found: " + index);  

    Comparable target1 = ("John Smith"); 
    System.out.println("Target1: "+target1.toString()); 
    found = DVD.searchForDVD(target1.toString()); 
    index=Integer.parseInt(found.toString()); 

    System.out.println ("Found1: " + index); 
    } 
} 



    class DVDCollection 
    { 
     public static DVD[] list; 
     private int count; 
    private double totalCost; 

    public DVDCollection() 
    { 
     list = new DVD[100]; 
    count = 0; 
    totalCost = 0; 
    } 
    public void addDVD (String title, String director, int year, double cost, boolean bluray) 
    { 
    list[count] = new DVD (title, director, year, cost, bluray); 
    for (int index = 1; index < list.length; index++) 
    { 

     DVD key = list[count]; 
     int position = count; 

     while (position > 0 && key.compareTo(list[position-1]) < 0) 
     { 
      list[position] = list[position-1]; 
      position--; 
     } 
     list[position] = key; 

    } 
    totalCost += cost; 
    count++; 
    } 

    @Override 
    public String toString() 
    { 
    NumberFormat fmt = NumberFormat.getCurrencyInstance(); 

    String report = "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n"; 
    report += "My DVD Collection\n\n"; 

    report += "Number of DVDs: " + count + "\n"; 
    report += "Total cost: " + fmt.format(totalCost) + "\n"; 
    report += "Average cost: " + fmt.format(totalCost/count); 

    report += "\n\nDVD List:\n\n"; 

    for (int dvd = 0; dvd < count; dvd++) 
    report += list[dvd].toString() + "\n"; 

    return report; 
    } 

} 

class DVD implements Comparable 
{ 
private String title, director; 
private int year; 
private double cost; 
private boolean bluray; 

public DVD (String title, String director, int year, double cost, boolean bluray) 
{ 
    this.title = title; 
    this.director = director; 
    this.year = year; 
    this.cost = cost; 
    this.bluray = bluray; 
} 

@Override 
public String toString() 
{ 
    NumberFormat fmt = NumberFormat.getCurrencyInstance(); 

    String description; 

    description = fmt.format(cost) + "\t" + year + "\t"; 
    description += title + "\t" + director; 

    if (bluray) 
    description += "\t" + "Blu-Ray"; 

    return description; 
    } 

    public String getDirector() 
    { 
    return director; 
} 

@Override 
public int compareTo (Object list) 
{ 
    int result; 

    String otherDirector = ((DVD)list).getDirector(); 
    result = director.compareTo(otherDirector); 

    return result; 
} 

public static int searchForDVD (String director) 
{ 
    boolean flag=false; 
    for(int i=0;i<DVDCollection.list.length;i++) 
    { 
     if(DVDCollection.list[i]!=null) 
     { 
      System.out.println("Director: "+DVDCollection.list[i].getDirector()); 
      if(DVDCollection.list[i].getDirector().equals(director)) 
      { 
       flag=true; 
       return i; 
      } 
     }    
    } 
    if(!flag) 
     return -1; 
    return -1; 

    }  

}