# How to log uncaught exceptions in Java

In Java, uncaught exceptions can be logged using a combination of the `Thread.UncaughtExceptionHandler` interface and the `setDefaultUncaughtExceptionHandler` method. This allows you to define a global handler for uncaught exceptions that occur in your Java application. Here's a step-by-step guide on how to set up logging for uncaught exceptions:

Create a custom `UncaughtExceptionHandler` class that implements the `Thread.UncaughtExceptionHandler` interface. This class will define how uncaught exceptions are handled, such as logging the exception details.

```java
import java.util.logging.Level;
import java.util.logging.Logger;

public class CustomUncaughtExceptionHandler implements Thread.UncaughtExceptionHandler {
    private static final Logger LOGGER = Logger.getLogger(CustomUncaughtExceptionHandler.class.getName());

    @Override
    public void uncaughtException(Thread t, Throwable e) {
        LOGGER.log(Level.SEVERE, "Uncaught exception in thread: " + t.getName(), e);
    }
}
```

Set the custom `UncaughtExceptionHandler` as the default handler for uncaught exceptions using the `setDefaultUncaughtExceptionHandler` method. You can do this in the main method of your Java application or at an appropriate location where you want to set the global handler.

```java
public class Main {
    public static void main(String[] args) {
        // Set custom uncaught exception handler
        Thread.setDefaultUncaughtExceptionHandler(new CustomUncaughtExceptionHandler());

        // Rest of your application code...
    }
}
```

Now, if an uncaught exception occurs in any thread of your Java application, the `CustomUncaughtExceptionHandler` class's `uncaughtException` method will be called, and it will log the exception details using a logger (in this case, the Java `Logger` class).

Make sure to configure the logger to write the logs to a file or another appropriate destination based on your logging requirements. You can configure the logger's level, format, and other settings to suit your needs.

Note: This approach will handle uncaught exceptions in non-daemon threads. If you have daemon threads in your application that might throw uncaught exceptions, you should handle them explicitly within those threads or use a separate mechanism to catch and handle them.

To learn more about logging, visit [Better Stack Community](https://betterstack.com/community/guides/logging/).

[ad-logs]