Added exception handling code for proper http response messages

src/main/java/com/StudentServices/MarksService/exception/ErrorDetails.java

+package com.StudentServices.MarksService.exception;
+
+import java.util.Date;
+
+public class ErrorDetails {
+    private Date timestamp;
+    private String message;
+    private String details;
+
+    public ErrorDetails(Date timestamp, String message, String details) {
+        this.timestamp = timestamp;
+        this.message = message;
+        this.details = details;
+    }
+
+    public Date getTimestamp() {
+        return timestamp;
+    }
+
+    public void setTimestamp(Date timestamp) {
+        this.timestamp = timestamp;
+    }
+
+    public String getMessage() {
+        return message;
+    }
+
+    public void setMessage(String message) {
+        this.message = message;
+    }
+
+    public String getDetails() {
+        return details;
+    }
+
+    public void setDetails(String details) {
+        this.details = details;
+    }
+
+}

src/main/java/com/StudentServices/MarksService/exception/GlobalExceptionHandler.java

+package com.StudentServices.MarksService.exception;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.context.request.WebRequest;
+import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;
+
+import java.util.Date;
+
+public class GlobalExceptionHandler extends ResponseEntityExceptionHandler {
+    public ResponseEntity<?> resourceNotFoundException(ResourceNotFoundException ex, WebRequest webRequest) {
+        ErrorDetails errorDetails = new ErrorDetails(new Date(), ex.getMessage(), webRequest.getDescription(false));
+        return new ResponseEntity<>(errorDetails, HttpStatus.NOT_FOUND);
+    }
+}
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src/main/java/com/StudentServices/MarksService/exception/ResourceNotFoundException.java

+package com.StudentServices.MarksService.exception;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.ResponseStatus;
+
+@ResponseStatus(value = HttpStatus.NOT_FOUND)
+public class ResourceNotFoundException extends Exception {
+    public ResourceNotFoundException(String message) {
+        super(message);
+    }
+}
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