Java Custom Exception

2018-06-26 14:48:41 +08:00
parent 3cab703646
commit a0b0e1c705
7 changed files with 120 additions and 7 deletions
@@ -0,0 +1,43 @@
+package com.baeldung.customexception;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.util.Scanner;
+
+public class FileManager {
+
+    public static String getFirstLine(String fileName) throws IncorrectFileNameException {
+        try (Scanner file = new Scanner(new File(fileName))) {
+            if (file.hasNextLine()) {
+                return file.nextLine();
+            } else {
+                throw new IllegalArgumentException("Non readable file");
+            }
+        } catch (FileNotFoundException err) {
+            if (!isCorrectFileName(fileName)) {
+                throw new IncorrectFileNameException("Incorrect filename : " + fileName, err);
+            }
+            // Logging etc
+        } catch (IllegalArgumentException err) {
+            if (!containsExtension(fileName)) {
+                throw new IncorrectFileExtensionException("Filename does not contain extension : " + fileName, err);
+            }
+            // Other error cases and logging
+        }
+        return "Default First Line";
+    }
+
+    private static boolean containsExtension(String fileName) {
+        if (fileName.contains(".txt") || fileName.contains(".doc"))
+            return true;
+        return false;
+    }
+
+    private static boolean isCorrectFileName(String fileName) {
+        if (fileName.equals("wrongFileName.txt"))
+            return false;
+        else
+            return true;
+    }
+
+}
@@ -0,0 +1,9 @@
+package com.baeldung.customexception;
+
+public class IncorrectFileExtensionException extends RuntimeException{
+    private static final long serialVersionUID = 1L;
+
+    public IncorrectFileExtensionException(String errorMessage, Throwable err) {
+        super(errorMessage, err);
+    }
+}
@@ -0,0 +1,9 @@
+package com.baeldung.customexception;
+
+public class IncorrectFileNameException extends Exception {
+    private static final long serialVersionUID = 1L;
+    
+    public IncorrectFileNameException(String errorMessage, Throwable err) {
+        super(errorMessage, err);
+    }
+}