public class Main {

	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");
	}

	static String buildSelectSql(String table, String[] fields) {
		StringBuilder sb = new StringBuilder(1024);
		sb.append("SELECT ");
		StringJoiner sj = new StringJoiner(", ");
		for (String field:
			 fields) {
			sj.add(field);
		}
		sb.append(sj).append(" FROM").append(" ").append(table);
		return "" + sb;
	}

}