public class StringJoinerMain {

static String buildSelectSql(String table, String[] fields) {

        StringJoiner stringJoiner = new StringJoiner(", ", "SELECT ", " FROM " + table);

        for (String field : fields) {

        stringJoiner.add(field);

        }

        String result = stringJoiner.toString();

        return result;

    }

public static void main(String[] args) {

        String[] fields = { "name", "position", "salary" };

        String table = "employee";

        String select = buildSelectSql(table, fields);

        System.out.println(select);

        System.out.println("SELECT name, position, salary FROM employee".equals(select) ? "测试成功" : "测试失败");

    }

}