Why use SLF4J over Log4J for logging in Java

On the other hand if you use SLF4J, you can get same result in much concise format as shown below :

logger.debug("Processing trade with id: {} and symbol : {} ", id, symbol);

In SLF4J, we don't need String concatenation and don't incur cost of temporary not need String. Instead, we write log message in a template format with placeholder and supply actual value as parameters.

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