Java 9 Private Interface Methods: Meningkatkan Enkapsulasi dan Penggunaan Ulang Kode
Sebelum Java 8, antarmuka dapat memiliki variabel/metode dengan tipe berikut.
- Variabel konstanta
- Metode abstraksi
Jadi kita tidak dapat memiliki implementasi metode dalam antarmuka atau lebih tepatnya implementasi default sebelum Java 8. Lihat contoh.
Live Demo
public class Tester { public static void main(String []args) { LogOracle log = new LogOracle(); log.logInfo(""); log.logWarn(""); log.logError(""); log.logFatal(""); LogMySql log1 = new LogMySql(); log1.logInfo(""); log1.logWarn(""); log1.logError(""); log1.logFatal(""); } } final class LogOracle implements Logging { @Override public void logInfo(String message) { getConnection(); System.out.println("Log Message : " + "INFO"); closeConnection(); } @Override public void logWarn(String message) { getConnection(); System.out.println("Log Message : " + "WARN"); closeConnection(); } @Override public void logError(String message) { getConnection(); System.out.println("Log Message : " + "ERROR"); closeConnection(); } @Override public void logFatal(String message) { getConnection(); System.out.println("Log Message : " + "FATAL"); closeConnection(); } @Override public void getConnection() { System.out.println("Open Database connection"); } @Override public void closeConnection() { System.out.println("Close Database connection"); } } final class LogMySql implements Logging { @Override public void logInfo(String message) { getConnection(); System.out.println("Log Message : " + "INFO"); closeConnection(); } @Override public void logWarn(String message) { getConnection(); System.out.println("Log Message : " + "WARN"); closeConnection(); } @Override public void logError(String message) { getConnection(); System.out.println("Log Message : " + "ERROR"); closeConnection(); } @Override public void logFatal(String message) { getConnection(); System.out.println("Log Message : " + "FATAL"); closeConnection(); } @Override public void getConnection() { System.out.println("Open Database connection"); } @Override public void closeConnection() { System.out.println("Close Database connection"); } } interface Logging { String ORACLE = "Oracle_Database"; String MYSQL = "MySql_Database"; void logInfo(String message); void logWarn(String message); void logError(String message); void logFatal(String message); void getConnection(); void closeConnection(); } Output
Anda akan melihat output berikut.
Open Database connection Log Message : INFO Close Database connection Open Database connection Log Message : WARN Close Database connection Open Database connection Log Message : ERROR Close Database connection Open Database connection Log Message : FATAL Close Database connection
Dalam contoh di atas, setiap metode log memiliki implementasinya sendiri. Dengan Java 8, antarmuka dapat memiliki variabel/metode dengan tipe berikut.
- Variabel konstanta
- Metode abstraksi
- Metode default
- Metode statis
Mari kita miliki implementasi default dan metode statis dalam antarmuka itu sendiri menggunakan Java 8.
Live Demo
public class Tester { public static void main(String []args) { LogOracle log = new LogOracle(); log.logInfo(""); log.logWarn(""); log.logError(""); log.logFatal(""); LogMySql log1 = new LogMySql(); log1.logInfo(""); log1.logWarn(""); log1.logError(""); log1.logFatal(""); } } final class LogOracle implements Logging { } final class LogMySql implements Logging { } interface Logging { String ORACLE = "Oracle_Database"; String MYSQL = "MySql_Database"; default void logInfo(String message) { getConnection(); System.out.println("Log Message : " + "INFO"); closeConnection(); } default void logWarn(String message) { getConnection(); System.out.println("Log Message : " + "WARN"); closeConnection(); } default void logError(String message) { getConnection(); System.out.println("Log Message : " + "ERROR"); closeConnection(); } default void logFatal(String message) { getConnection(); System.out.println("Log Message : " + "FATAL"); closeConnection(); } static void getConnection() { System.out.println("Open Database connection"); } static void closeConnection() { System.out.println("Close Database connection"); } } Output
Anda akan melihat output berikut.
Open Database connection Log Message : INFO Close Database connection Open Database connection Log Message : WARN Close Database connection Open Database connection Log Message : ERROR Close Database connection Open Database connection Log Message : FATAL Close Database connection
Dalam contoh di atas, kita memiliki pengulangan lagi. Dengan Java 9, antarmuka dapat memiliki variabel/metode dengan tipe berikut.
- Variabel konstanta
- Metode abstraksi
- Metode default
- Metode statis
- Metode private
- Metode private statis
Mari kita miliki metode private dan gunakan dalam Java 9.
public class Tester { public static void main(String []args) { LogOracle log = new LogOracle(); log.logInfo(""); log.logWarn(""); log.logError(""); log.logFatal(""); LogMySql log1 = new LogMySql(); log1.logInfo(""); log1.logWarn(""); log1.logError(""); log1.logFatal(""); } } final class LogOracle implements Logging { } final class LogMySql implements Logging { } interface Logging { String ORACLE = "Oracle_Database"; String MYSQL = "MySql_Database"; private void log(String message, String prefix) { getConnection(); System.out.println("Log Message : " + prefix); closeConnection(); } default void logInfo(String message) { log(message, "INFO"); } default void logWarn(String message) { log(message, "WARN"); } default void logError(String message) { log(message, "ERROR"); } default void logFatal(String message) { log(message, "FATAL"); } private static void getConnection() { System.out.println("Open Database connection"); } private static void closeConnection() { System.out.println("Close Database connection"); } } Output
Anda akan melihat output berikut.
Open Database connection Log Message : INFO Close Database connection Open Database connection Log Message : WARN Close Database connection Open Database connection Log Message : ERROR Close Database connection Open Database connection Log Message : FATAL Close Database connection
