求救：覆盖ResultSet的getFloat()方法！

[煜知搬砖者]

当字段内容为null时，ResultSet的getFloat方法得到的值是0.0
请问我想这样：当字段内容为null时，得到-1.00,
请问大家有和建议？

[study_body]

自己建立一个对象，可以从ResultSet中继承，然后覆盖该方法

[煜知搬砖者]

关键是怎么写那个方法阿，呵呵

[煜知搬砖者]

请大家给点思路，谢谢了。

[danceflash]

可以先看看ResultSet的getFloat()方法的源代码

[jinmin]

可以参考：
// Decompiled by Jad v1.5.7. Copyright 1997-99 Pavel Kouznetsov.
// Jad home page: http://www.geocities.com/SiliconValley/Bridge/8617/jad.html
// Decompiler options: packimports(3)
// Source File Name: ResultSet.java

package java.sql;

import java.io.InputStream;
import java.math.BigDecimal;

// Referenced classes of package java.sql:
// SQLException, Date, Time, Timestamp,
// SQLWarning, ResultSetMetaData

public interface ResultSet
{

public abstract boolean next()
throws SQLException;

public abstract void close()
throws SQLException;

public abstract boolean wasNull()
throws SQLException;

public abstract String getString(int i)
throws SQLException;

public abstract boolean getBoolean(int i)
throws SQLException;

public abstract byte getByte(int i)
throws SQLException;

public abstract short getShort(int i)
throws SQLException;

public abstract int getInt(int i)
throws SQLException;

public abstract long getLong(int i)
throws SQLException;

public abstract float getFloat(int i)
throws SQLException;

public abstract double getDouble(int i)
throws SQLException;

public abstract BigDecimal getBigDecimal(int i, int j)
throws SQLException;

public abstract byte[] getBytes(int i)
throws SQLException;

public abstract Date getDate(int i)
throws SQLException;

public abstract Time getTime(int i)
throws SQLException;

public abstract Timestamp getTimestamp(int i)
throws SQLException;

public abstract InputStream getAsciiStream(int i)
throws SQLException;

public abstract InputStream getUnicodeStream(int i)
throws SQLException;

public abstract InputStream getBinaryStream(int i)
throws SQLException;

public abstract String getString(String s)
throws SQLException;

public abstract boolean getBoolean(String s)
throws SQLException;

public abstract byte getByte(String s)
throws SQLException;

public abstract short getShort(String s)
throws SQLException;

public abstract int getInt(String s)
throws SQLException;

public abstract long getLong(String s)
throws SQLException;

public abstract float getFloat(String s)
throws SQLException;

public abstract double getDouble(String s)
throws SQLException;

public abstract BigDecimal getBigDecimal(String s, int i)
throws SQLException;

public abstract byte[] getBytes(String s)
throws SQLException;

public abstract Date getDate(String s)
throws SQLException;

public abstract Time getTime(String s)
throws SQLException;

public abstract Timestamp getTimestamp(String s)
throws SQLException;

public abstract InputStream getAsciiStream(String s)
throws SQLException;

public abstract InputStream getUnicodeStream(String s)
throws SQLException;

public abstract InputStream getBinaryStream(String s)
throws SQLException;

public abstract SQLWarning getWarnings()
throws SQLException;

public abstract void clearWarnings()
throws SQLException;

public abstract String getCursorName()
throws SQLException;

public abstract ResultSetMetaData getMetaData()
throws SQLException;

public abstract Object getObject(int i)
throws SQLException;

public abstract Object getObject(String s)
throws SQLException;

public abstract int findColumn(String s)
throws SQLException;
}

[study_body]

class abc extends ResultSet
{
void getFloat()
{
if(super.getFloat())=0 return -1;
else return super.getFloat();
}
}

[baihuazhang]

提个不知道对不对的建议啊,可以设置一个变量a=rs.getFloat();
if (a==0.0)
a=-1.0;
请各位大虾指教

[study_body]

抱歉，应该是
class abc extends ResultSet
{
float getFloat()
{
if(super.getFloat())=0 return -1;
else return super.getFloat();
}
}

[study_body]

class abc extends ResultSet
{
float getFloat(int i)
{
if(super.getFloat(i))=0 return -1;
else return super.getFloat(i);
}
}

思路就是这样，具体实现再自己看看

[danceflash]

恩~~~

study_body(珍惜每一天)的方法不错

学习、学习~~~^_^

[煜知搬砖者]

还有一个问题比较关键，要是字段本身的值是0的话，那怎么办呢？

[煜知搬砖者]

to: jinmin(★猪猪★)
有没有实现的源代码？

[ChDw]

float a = rs.getFloat(1);
if(rs.wasNull())
a = -1.0

[caoze]

float a = ( rs.getFloat("af") == 0.0? -1.0 : rs.getFloat("af") );

[bdsc]

class abc extends ResultSet 对么？！

ChDw(米)
是最可行的
float a = rs.getFloat(1);
if(rs.wasNull())
a = -1.0

[ChDw]

自己继承ResultSet是不可行的，因为
ResultSet rs = ....
实际上rs并不是ResultSet的这个类，它仅仅是一个实现了这个接口的类
根据不同的数据库厂商实际是不同的，就是说
ResultSet rs = ...;
System.out.println("Class：" + rs.getClass().getName());
你这样就可以看到实际上rs的类是什么了

[煜知搬砖者]

问题得到解决。 ChDw(米)的方法是正确的。
谢谢。

[ChDw]

那赶快给分我！！！ :)

[kaolaxiong]

try{}catch(Exception ex){

}