2015.11.26

【Java】サヨナラNullチェック！requireNonNullが便利すぎた！

mokabuu

こんなコード

private final static String SQL = "select NEWSONG from BANDSONGS where BANDNAME = ?";
public String getNewSong(Connection connection, String bandname) throws IOException {
    checkNull(bandname);
    try (PreparedStatement preparedStatement = connection.prepareStatement(SQL);) {
        preparedStatement.setString(1, bandname);
        try (ResultSet resultSet = preparedStatement.executeQuery();) {
            if (resultSet.next()) {
                String newSong = resultSet.getString(1);
                return newSong;
            } else {
                return null;
            }
        }
    } catch (SQLException e) {
        logger.error("Failed to get newSong!!", e);
        throw new IOException(e);
    }
}
 
private void checkNull(String bandname) {
    if (bandname == null) {
        throw new NullPointerException("bandname is null!!");
    }
}

本日こんな感じのコードを書いていると
友人が「java.Util.Objects」にいい感じのあるよと教えてくれました。

その名も「requireNonNull」先輩。

この先輩があまりに便利過ぎたので備忘録を書いておきます。

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さっきのコードがこうなる

private final static String SQL = "select NEWSONG from BANDSONGS where BANDNAME = ?";
public String getNewSong(Connection connection, String bandname) throws IOException {
    Objects.requireNonNull(bandname, "bandname cannot be null!!");
    try (PreparedStatement preparedStatement = connection.prepareStatement(SQL);) {
        preparedStatement.setString(1, bandname);
        try (ResultSet resultSet = preparedStatement.executeQuery();) {
            if (resultSet.next()) {
                String newSong = resultSet.getString(1);
                return newSong;
            } else {
                return null;
            }
        }
    } catch (SQLException e) {
        logger.error("Failed to get newSong!!", e);
        throw new IOException(e);
    }
}