java中的接口和继承(interface and inheritance in java)

 您会错过颜色字段和where子句中的单引号。 
 
"UPDATE file1  SET  name='" + dt.getName()+ "',age='" + dt.getAge()+ "',color='"+dt.getColor()+ "'"
+ " WHERE name='" + dt.getName() + "'";
 
 此外，您应该使用参数化语句，原因有很多：防止SQL注入，提高可读性，以及DBMS通常更有效地执行查询。 
 
"UPDATE file1  SET  name=?,age=?,color=? WHERE NAME =?";

pst.setString(1, dt.getName());
pst.setInt(2, dt.getAge());
(etc...)

You miss the single quotes for the color field, and in the where clause.
 
"UPDATE file1  SET  name='" + dt.getName()+ "',age='" + dt.getAge()+ "',color='"+dt.getColor()+ "'"
+ " WHERE name='" + dt.getName() + "'";
 
Also, you should use paramaterized statements, for a lot of reasons: protection against sql injection, improved readability and often more efficient query execution by your DBMS.
 
"UPDATE file1  SET  name=?,age=?,color=? WHERE NAME =?";

pst.setString(1, dt.getName());
pst.setInt(2, dt.getAge());
(etc...)