Обсуждение: Low Priority: Harmless but useless code in AbstractJdbc1Statement.setObject???

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Hi,

While looking at the PreparedStatement functionality of the
postgresql driver I ran in
AbstractJdbc1Statement.setObject(int parameterIndex, Object x))
into the following snippet of code.

if (x == null)
{
    int l_sqlType;
    if (x instanceof String)
        l_sqlType = Types.VARCHAR;
    else if (x instanceof BigDecimal)
        l_sqlType = Types.DECIMAL;
    else if (x instanceof Short)
        l_sqlType = Types.SMALLINT;
    else if (x instanceof Integer)
        l_sqlType = Types.INTEGER;
    else if (x instanceof Long)
        l_sqlType = Types.BIGINT;
    else if (x instanceof Float)
        l_sqlType = Types.FLOAT;
    else if (x instanceof Double)
        l_sqlType = Types.DOUBLE;
    else if (x instanceof byte[])
        l_sqlType = Types.BINARY;
    else if (x instanceof java.sql.Date)
        l_sqlType = Types.DATE;
    else if (x instanceof Time)
        l_sqlType = Types.TIME;
    else if (x instanceof Timestamp)
        l_sqlType = Types.TIMESTAMP;
    else if (x instanceof Boolean)
        l_sqlType = Types.OTHER;
    else
        l_sqlType = Types.OTHER;

    setNull(parameterIndex, l_sqlType);
    return ;
}

According to my O'Reilly Java Language Reference, x instanceof
<Type>, where x == null will always return false...am I overlooking
something?

I tested it using the following class:

/**
 * test class for 'x instanceof <Class>' where x is null
 */
public class InstanceOf {
    public static void main(String[] args) {

        Object x = null;

        System.out.println("x instanceof Object: "+(x instanceof Object));
        System.out.println("x instanceof String: "+(x instanceof String));
        System.out.println("x instanceof Integer: "+(x instanceof
Integer));

    }
}

With java version "1.4.1_01" I get:

$ java InstanceOf
x instanceof Object: false
x instanceof String: false
x instanceof Integer: false

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Jeroen,

Good eye!

Thanks,

Dave
On Tue, 2003-03-25 at 05:23, Jeroen Habets wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Hi,
>
> While looking at the PreparedStatement functionality of the
> postgresql driver I ran in
> AbstractJdbc1Statement.setObject(int parameterIndex, Object x))
> into the following snippet of code.
>
> if (x == null)
> {
>     int l_sqlType;
>     if (x instanceof String)
>         l_sqlType = Types.VARCHAR;
>     else if (x instanceof BigDecimal)
>         l_sqlType = Types.DECIMAL;
>     else if (x instanceof Short)
>         l_sqlType = Types.SMALLINT;
>     else if (x instanceof Integer)
>         l_sqlType = Types.INTEGER;
>     else if (x instanceof Long)
>         l_sqlType = Types.BIGINT;
>     else if (x instanceof Float)
>         l_sqlType = Types.FLOAT;
>     else if (x instanceof Double)
>         l_sqlType = Types.DOUBLE;
>     else if (x instanceof byte[])
>         l_sqlType = Types.BINARY;
>     else if (x instanceof java.sql.Date)
>         l_sqlType = Types.DATE;
>     else if (x instanceof Time)
>         l_sqlType = Types.TIME;
>     else if (x instanceof Timestamp)
>         l_sqlType = Types.TIMESTAMP;
>     else if (x instanceof Boolean)
>         l_sqlType = Types.OTHER;
>     else
>         l_sqlType = Types.OTHER;
>
>     setNull(parameterIndex, l_sqlType);
>     return ;
> }
>
> According to my O'Reilly Java Language Reference, x instanceof
> <Type>, where x == null will always return false...am I overlooking
> something?
>
> I tested it using the following class:
>
> /**
>  * test class for 'x instanceof <Class>' where x is null
>  */
> public class InstanceOf {
>     public static void main(String[] args) {
>
>         Object x = null;
>
>         System.out.println("x instanceof Object: "+(x instanceof Object));
>         System.out.println("x instanceof String: "+(x instanceof String));
>         System.out.println("x instanceof Integer: "+(x instanceof
> Integer));
>
>     }
> }
>
> With java version "1.4.1_01" I get:
>
> $ java InstanceOf
> x instanceof Object: false
> x instanceof String: false
> x instanceof Integer: false
>
> -----BEGIN PGP SIGNATURE-----
> Version: PGPfreeware 6.5.3 for non-commercial use <http://www.pgp.com>
>
> iQA/AwUBPoAgA/IWL7P9qCbyEQKevQCgwTUiGCmM8h+Bqmz7OZRlj/rAEZ4AmwY3
> fUmH1CLmMNXfmrChdFn/qtne
> =Ndff
> -----END PGP SIGNATURE-----
>
>
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--
Dave Cramer <Dave@micro-automation.net>