Java9: Private Interface Methods

Java9 allows to have private interface methods so that the default methods can use them reduce repeating codes.

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public class PrivateInterfaceMethods {
    public static void main(String[] args) {
        OracleLogger oracleLogger = new OracleLogger();
        oracleLogger.logError("error in oracle connection");
        oracleLogger.logInfo("Connection established");
    }
}

interface Logging{
    String ORACLE = "Oracle_Database";
    String MYSQL = "MySql_Database";

    default void logInfo(String message) {
        log(message, "INFO");
    }
    default void logError(String message) {
        log(message, "ERROR");
    }
    private void log(String message, String prefix){
        System.out.println("Log Message : " + prefix);
    }
}

final class OracleLogger implements Logging {}
final class MySqlLogger implements Logging {}

private log() method is used by both default methods to reduce repeating.

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