final:
1.一个永不改变的常量，要用大写英文表示，英文单词之间要用下划线表示
2.不可覆盖方法
3.不可被继承
package cn.zzx.data.pc;
public interface IB { //声明接口
public static final String DATABASES = "mariadb";
public interface TABLES{ // 表
public interface STUDENT{ //学生表
public static final String TABLENAME = "student";
public interface FIELDS{ //字段
public static final String ID = "id";
public static final String NAME = "name";
public static final String SEX = "sex";
}
public interface SQL{ //SQL插入与更新
public static final String INSERT = "insert into student values()";
public static final String UPDATE = "update student set id='' where id=''";
}
}
}
public interface STUDENT_TWO {
}
}
package cn.zzx.data.pc;
import cn.zzx.data.pc.IB.TABLES.STUDENT;
public class Demo {
public static void main(String args[]){
String databasesName = IB.DATABASES;
// String id = IB.TABLES.STUDENT.FIELDS.ID; //可以接口的调用
String id = STUDENT.FIELDS.ID; //也可以导包嵌套接口调用
String sql = STUDENT.SQL.INSERT;
System.out.printf("{%s}\r{%s}\n{%s}",databasesName,id,sql);
}
}
