Factory Pattern ~ A Modern Approach - 3

CsvReader.java

public class CsvReader implements FileReader {
  // some code here
  
  public String readFile(String filePath) {
    // ...
    
    return fileContent;
  }

}

ExcelReader.java

public class ExcelReader implements FileReader {
  // some code here
  
  public String readFile(String filePath) {
    // ...
    
    return fileContent;
  }

}

FileOperations.java

public class FileOperations {
  
  // some code here
  
  public String readFile(String filePath){
    FileReader reader;
    
    if(isPdfFile(filePath)){
      reader = new PdfReader();
    }
    else if(isExcelFile(filePath)) {
      reader = new ExcelReader();
    }
    else if(isCsvFile(filePath)){
      reader = new CsvReader();
    }
    else {
      throw new UnsupportedFileExtension("...");
    }
    
    return reader.readfile(filePath)
  }
  
  
  private String readPdfFile(String filePath) {
    // some code here
    
    return fileContent;
  }
  
  private String readExcelFile(String filePath) {
    // some code here
    
    return fileContent;
  }
}

FileReader.java

public interface FileReader{
  public String readFile(String filePath);
}

PdfReader.java

public class PdfReader implements FileReader {
  // some code here
  
  public String readFile(String filePath) {
    // ...
    
    return fileContent;
  }

}