You have been assigned the task of writing a program that determines the number of classes in a Java project. Your program should analyze a given Java codebase and count the number of classes present. 

You need to implement the following function:

```java
public int countClasses(String code)
```

**Input**:
- The function takes in a string parameter `code` (1 <= code.length <= 10^5), representing the Java codebase. The codebase is guaranteed to be syntactically correct.

**Output**:
- The function should return an integer representing the total number of classes in the Java codebase.

**Note**:
- A class in Java is defined by the keyword `class`, followed by the class name, and the code enclosed within curly braces `{}`.
- The Java codebase may contain nested classes, but only the outermost classes will be counted.
- The Java codebase may also contain single-line and multi-line comments, which should be ignored when counting classes.

**Example**:
```java
String code = "public class Solution {
                   public static void main(String[] args) {
                       System.out.println(\"Hello, World!\");
                   }
               }";
countClasses(code); // Output: 1

String code = "public class Solution {
                   private class InnerClass {
                       // Nested class
                   }
               }";
countClasses(code); // Output: 1

String code = "// Single line comment\n" +
              "/* Multi-line\n" +
              "   comment */\n" +
              "public class Solution {
                   public static void main(String[] args) {
                       System.out.println(\"Hello, World!\");
                   }
              }";
countClasses(code); // Output: 1

String code = "public class Solution {
                   class InnerClass {
                       // Nested class
                   }
               }
               public class AnotherClass {
                   // Another class
               }";
countClasses(code); // Output: 2
```
user
Sure, I can help you write a function in Java that counts the number of classes in a Java codebase. Here's a basic implementation based on the information provided:

```java
import javax.tools.JavaCompiler;
import javax.tools.JavaFileManager;
import javax.tools.JavaFileObject;
import javax.tools.SimpleJavaFileObject;
import javax.tools.StandardJavaFileManager;
import javax.tools.ToolProvider;
import org.apache.commons.io.FilenameUtils;

import java.io.File;
import java.io.FilenameFilter;
import java.util.ArrayList;
import java.util.List;

public class ClassCounter {

    // This method analyzes the given code and counts the number of classes.
    // It returns the number of classes found in the code.
    public static int countClasses(String code) {
        try {
            JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
            JavaFileManager fileManager = new ClasspathFileManager(compiler);
            List<JavaFileObject> compilationUnits = new ArrayList<>();
            compilationUnits.add(new ClasspathJavaFileObject(compiler, FilenameUtils.normalize(new File(code).toURI().toString()), null, null));
            JavacTask task = compiler.getTask(null, fileManager, null, null, null, compilationUnits);

            boolean success = task.call();

            if (success) {
                return compilationUnits.size();
            }
        } catch (Exception e) {
            // Handle any exceptions that may occur.
        }

        return 0;
    }
}

// A custom file object to be used with the JavacTask.
class ClasspathJavaFileObject extends SimpleJavaFileObject {

    ClasspathJavaFileObject(JavaCompiler compiler, String resource, String kind, File object) {
        super(compiler, resource, Kind.SOURCE);
        this.kind = kind;
        this.object = object;
    }

    @Override
    public Kind getKind() {
        return Kind.SOURCE;
    }

    private final String kind;
    private final File object;

    // This method is not used in the function but is required for the custom file object.
    @Override
    public File getSourceFile() {
        return object;
    }
}

// A FilenameFilter implementation to handle Java file extensions.
class JavaExtensionFilter implements FilenameFilter {

    @Override
    public boolean accept(File dir, String name) {
        return name.endsWith(".java");
    }
}
```

Explanation:

- The `ClasspathJavaFileObject` class is a custom `JavaFileObject` for use with the `JavacTask`, allowing us to compile Java files from the classpath.

- The `JavaExtensionFilter` class extends `FilenameFilter` and is used to filter out Java files, allowing us to specify a file extension (e.g., `.java`) without resorting to regular expressions.

- The `countClasses` function first creates a `JavaFileManager` instance, which in turn creates a `JavaFileObject` instance that represents the `code` string.

- It then creates a `JavacTask` that calls the code analysis module of the Java compiler.

- The `JavacTask.call()` method compiles the `code` string and returns a boolean indicating whether compilation was successful or not.

- If compilation was successful, it retrieves the `List` of compiled files obtained in the constructor of the `JavacTask`, which is a list of}`ClasspathJavaFileObject` instances, and returns the length of the list, i.e., the number of classes found.

- If any exception occurs, it returns `0`, which indicates no classes found.
assistant
You have been assigned the task of writing a program that determines the number of classes in a Java project. Your program should analyze a given Java codebase and count the number of classes present. 

You need to implement the following function:

```java
public int countClasses(String code)
```

**Input**:
- The function takes in a string parameter `code` (1 <= code.length <= 10^5), representing the Java codebase. The codebase is guaranteed to be syntactically correct.

**Output**:
- The function should return an integer representing the total number of classes in the Java codebase.

**Note**:
- A class in Java is defined by the keyword `class`, followed by the class name, and the code enclosed within curly braces `{}`.
- The Java codebase may contain nested classes, but only the outermost classes will be counted.
- The Java codebase may also contain single-line and multi-line comments, which should be ignored when counting classes.

**Example**:
```java
String code = "public class Solution {
                   public static void main(String[] args) {
                       System.out.println(\"Hello, World!\");
                   }
               }";
countClasses(code); // Output: 1

String code = "public class Solution {
                   private class InnerClass {
                       // Nested class
                   }
               }";
countClasses(code); // Output: 1

String code = "// Single line comment\n" +
              "/* Multi-line\n" +
              "   comment */\n" +
              "public class Solution {
                   public static void main(String[] args) {
                       System.out.println(\"Hello, World!\");
                   }
              }";
countClasses(code); // Output: 1

String code = "public class Solution {
                   class InnerClass {
                       // Nested class
                   }
               }
               public class AnotherClass {
                   // Another class
               }";
countClasses(code); // Output: 2
```
user
To solve this problem, you can use a state machine approach to keep track of whether you are currently inside a single-line comment, multi-line comment, or class definition. You can also use a stack to keep track of the nesting level of curly braces `{}`. Here is a possible implementation in Java:

```java
import java.util.*;

public class ClassCounter {
    public int countClasses(String code) {
        int count = 0;
        boolean inSingleLineComment = false;
        boolean inMultiLineComment = false;
        boolean inClassDefinition = false;
        Deque<Character> braceStack = new ArrayDeque<>();

        for (char c : code.toCharArray()) {
            if (inSingleLineComment) {
                // Ignore characters inside single-line comment
                if (c == '\n') {
                    inSingleLineComment = false;
                }
            } else if (inMultiLineComment) {
                // Ignore characters inside multi-line comment
                if (c == '*' && !braceStack.isEmpty() && braceStack.peek() == '/') {
                    braceStack.pop();
                    inMultiLineComment = false;
                } else if (c != '*') {
                    braceStack.push(c);
                }
            } else {
                // Handle other characters
                if (c == '/') {
                    // Check for start of single-line or multi-line comment
                    if (code.charAt(Math.min(code.length() - 1, code.indexOf(c) + 1)) == '/') {
                        inSingleLineComment = true;
                    } else if (code.charAt(Math.min(code.length() - 1, code.indexOf(c) + 1)) == '*') {
                        inMultiLineComment = true;
                        braceStack.push(c);
                    }
                } else if (!inClassDefinition && c == 'c' && code.substring(Math.max(0, code.indexOf(c) - 3), Math.min(code.length(), code.indexOf(c) + 5)).equals("class ")) {
                    // Found start of class definition
                    inClassDefinition = true;
                    count++;
                } else if (c == '{') {
                    // Increment nesting level
                    braceStack.push(c);
                } else if (c == '}') {
                    // Decrement nesting level
                    if (!braceStack.isEmpty()) {
                        braceStack.pop();
                    }
                    if (braceStack.isEmpty()) {
                        // End of class definition
                        inClassDefinition = false;
                    }
                }
            }
        }

        return count;
    }
}
```

This implementation uses a `Deque` to store the nesting level of curly braces. It iterates through each character in the input string and updates the state variables accordingly. If it encounters a 'c' character that is part of a "class" keyword and it is not currently inside a class definition, it increments the class count. If it encounters a '{' character, it pushes it onto the brace stack, and if it encounters a '}' character, it pops a '{' from the stack. If the stack becomes empty after popping a '}', it means that the current class definition has ended. Single-line and multi-line comments are ignored by tracking whether the current character is inside a comment and skipping characters accordingly.
assistant