Eclipse错误：“编辑器不包含主类型”

我似乎无法在Eclipse中运行以下代码。 我有一个main方法，这是当前打开的文件。 我甚至尝试了“运行方式”选项，但我不断收到此错误：“编辑器不包含主类型”。 我在这做错了什么？

public class cfiltering { /** * @param args */ //remember this is just a reference //this is a 2d matrix ie user*movie private static int user_movie_matrix[][]; //remember this is just a reference //this is a 2d matrix ie user*user and contains //the similarity score for every pair of users. private float user_user_matrix[][]; public cfiltering() { //this is default constructor, which just creates the following: //ofcourse you need to overload the constructor so that it takes in the dimensions //this is 2d matrix of size 1*1 user_movie_matrix=new int[1][1]; //this is 2d matrix of size 1*1 user_user_matrix=new float[1][1]; } public cfiltering(int height, int width) { user_movie_matrix=new int[height][width]; user_user_matrix=new float[height][height]; } public static void main(String[] args) { //1.0 this is where you open/read file //2.0 read dimensions of number of users and number of movies //3.0 create a 2d matrix ie user_movie_matrix with the above dimensions. //4.0 you are welcome to overload constructors ie create new ones. //5.0 create a function called calculate_similarity_score //you are free to define the signature of the function //The above function calculates similarity score for every pair of users //6.0 create a new function that prints out the contents of user_user_matrix try { //fileinputstream just reads in raw bytes. FileInputStream fstream = new FileInputStream("inputfile.txt"); //because fstream is just bytes, and what we really need is characters, we need //to convert the bytes into characters. This is done by InputStreamReader. BufferedReader br = new BufferedReader(new InputStreamReader(fstream)); int numberOfUsers=Integer.parseInt(br.readLine()); int numberOfMovies=Integer.parseInt(br.readLine()); //Now you have numberOfUsers and numberOfMovies to create your first object. //this object will initialize the user_movie_matrix and user_user_matrix. new cfiltering(numberOfUsers, numberOfMovies); //this is a blankline being read br.readLine(); String row; int userNo = 0; while ((row = br.readLine()) != null) { //now lets read the matrix from the file String allRatings[]=row.split(" "); int movieNo = 0; for (String singleRating:allRatings) { int rating=Integer.parseInt(singleRating); //now you can start populating your user_movie_matrix System.out.println(rating); user_movie_matrix[userNo][movieNo]=rating; ++ movieNo; } ++ userNo; } } catch(Exception e) { System.out.print(e.getMessage()); } } } 

Answer 1

尝试关闭并重新打开文件，然后按Ctrl+F11 。

validation您运行的文件的名称是否与您正在使用的项目的名称相同，并且该文件中的公共类的名称与您正在使用的项目的名称相同。

否则，重启Eclipse。 如果这解决了问题，请告诉我！ 否则，评论，我会尽力帮助。

Answer 2

您是否导入了文件读取包的包。

 import java.io.BufferedReader; import java.io.FileInputStream; import java.io.InputStreamReader; 

也在这里

 cfiltering(numberOfUsers, numberOfMovies); 

您是在尝试创建对象还是调用方法？

还有一件事：

 user_movie_matrix[userNo][movieNo]=rating; 

您正在为实例的成员分配值，就好像它是一个静态变量一样，也删除了Th in

 private int user_movie_matrix[][];Th 

希望这可以帮助。

Answer 3

private int user_movie_matrix[][];Th 。 应该是`private int user_movie_matrix[][]; 。

private int user_movie_matrix[][]; 应该是private static int user_movie_matrix[][];

cfiltering(numberOfUsers, numberOfMovies); 应该是new cfiltering(numberOfUsers, numberOfMovies);

在这些更改之后代码是否按预期工作超出了本答案的范围; 有几个语法/作用域错误。