i had a situation where i had to use this setDataVector function. I was puzzled to see there was an extra second argument(Vector columnIdentifiers) in the function. I'm just resetting the data. Why do i need to send the column identifiers?? And it doesn't take the old column identifiers by default if i don't pass the second argument. Irritating to add initialize a vector with column identifiers only for this purpose. Any idea why it's been done like that?
From the actual code, it looks to me like the method could have been better named. Something like setDataAndColumns() makes more sense. The internal code looks like this:
this.dataVector = nonNullVector(dataVector);
this.columnIdentifiers = nonNullVector(columnIdentifiers);
Passing in null for columnIdentifiers will simply remove all the columns in the table. I guess your controller class needs to keep a copy of the columnIdentifiers to pass in as required.
The setDataVector(...) method is invoked by all the constructor methods which require you to include both parameters.
Related
So i've got a bot that serves as a roleplaying mamager handeling combat, skill points and the like, i'm trying to make my code a bit more general so i can have less pages since they all do the same thing they just have different initilizers but i ran into a snag i need to check if the user has a minimum in a particular stat Strength, perceptions, agility, etc
so i call
mainSPECIAL = rows[0].Strength;
Here's the rub, weathers it strength, percpetion, intelligence, luck, whatever i'm always going to be checking Rows[0].that attribute ie Rows[0].Luck for luck perks, and i already set earlier in my initilizers
var PERKSPECIALName = "Strength";
But i can't call
mainSPECIAL = rows[0].PERKSPECIALName but there should be a way to do that right? so that when it sees "rows[0].PERKSPECIALName" it looks up "PERKSPECIALName" and then fetches the value of rows[0].Strength
For this you need to use reflection:
Field f1 = rows[0].getClass().getField(PERKSPECIALName);
Integer attribute = (Integer) f1.get(rows[0]);
Where "Integer" is the type of the element your pulling from the object (the type of strength)
The field must be declared as public! I think there is a way to obtain them when they are not public but it requires more code.
Seems like you have a set of integers that you need to identify with a constant identifier. You might find an EnumMap useful. Have a look at How to use enumMap in java.
Or if you want to only use a string to identify which perk you want to reference, just use a Map.
Java doesn't have reference-to-member like some other languages, so if you don't want to change your data structure, you are looking at using lambda functions or heavier language features to increase re-use, which seems like overkill for what you're trying to do.
I've got loads of the following to implement.
validateParameter(field_name, field_type, field_validationMessage, visibleBoolean);
Instead of having 50-60 of these in a row, is there some form of nested hashmap/4d array I can use to build it up and loop through them?
Whats the best approach for doing something like that?
Thanks!
EDIT: Was 4 items.
What you could do is create a new Class that holds three values. (The type, the boolean, and name, or the fourth value (you didn't list it)). Then, when creating the HashMap, all you have to do is call the method to get your three values. It may seem like more work, but all you would have to do is create a simple loop to go through all of the values you need. Since I don't know exactly what it is that you're trying to do, all I can do is provide an example of what I'm trying to do. Hope it applies to your problem.
Anyways, creating the Class to hold the three(or four) values you need.
For example,
Class Fields{
String field_name;
Integer field_type;
Boolean validationMessageVisible;
Fields(String name, Integer type, Boolean mv) {
// this.field_name = name;
this.field_type = type;
this.validationMessageVisible = mv;
}
Then put them in a HashMap somewhat like this:
HashMap map = new HashMap<String, Triple>();
map.put(LOCAL STRING FOR NAME OF FIELD, new Field(new Integer(YOUR INTEGER),new Boolean(YOUR BOOLEAN)));
NOTE: This is only going to work as long as these three or four values can all be stored together. For example if you need all of the values to be stored separately for whatever reason it may be, then this won't work. Only if they can be grouped together without it affecting the function of the program, that this will work.
This was a quick brainstorm. Not sure if it will work, but think along these lines and I believe it should work out for you.
You may have to make a few edits, but this should get you in the right direction
P.S. Sorry for it being so wordy, just tried to get as many details out as possible.
The other answer is close but you don't need a key in this case.
Just define a class to contain your three fields. Create a List or array of that class. Loop over the list or array calling the method for each combination.
The approach I'd use is to create a POJO (or some POJOs) to store the values as attributes and validate attribute by attribute.
Since many times you're going to have the same validation per attribute type (e.g. dates and numbers can be validated by range, strings can be validated to ensure they´re not null or empty, etc), you could just iterate on these attributes using reflection (or even better, using annotations).
If you need to validate on the POJO level, you can still reuse these attribute-level validators via composition, while you add more specific validations are you´re going up in the abstraction level (going up means basic attributes -> pojos -> pojos that contain other pojos -> etc).
Passing several basic types as parameters of the same method is not good because the parameters themselves don't tell much and you can easily exchange two parameters of the same type by accident in the method call.
I would like to have an option to call 'rawQuery' with a list of Integers passed into it, but it looks I can't: all 'rawQuery' methods require array of Strings...
Why? I can call 'toString' for each passed int object, but I don't see any logic here. Why Google don't provide rawQuery that accept list of Objects?
Are there any limitation or constrains for that?
Probably I miss something?
Thank you.
Probably because rawQuery isn't the prefered method of querying. And since sqlite columns basically don't have types, they probably don't want to assume calling toString on whatever it is you're passing.
SQLite supports the concept of "type affinity" on columns. The type
affinity of a column is the recommended type for data stored in that
column. The important idea here is that the type is recommended, not
required. Any column can still store any type of data. It is just that
some columns, given the choice, will prefer to use one storage class
over another. The preferred storage class for a column is called its
"affinity".
Is there a reason you want to use rawQuery instead of execSQL?
No complex objects are accepted in the list of parameters, as stated on the documentation for the parameter bindArgs:
Parameters
sql the SQL statement to be executed. Multiple statements separated by semicolons are not supported.
bindArgs only byte[], String, Long and Double are supported in bindArgs.
http://developer.android.com/reference/android/database/sqlite/SQLiteDatabase.html#execSQL(java.lang.String, java.lang.Object[]).
Just a quick one. If I'm using an EJBQL query with named parameters, can I use the same parameter name twice in a single query to avoid having to set the value twice when I actually want to run the query? For instance, I'd like to be able to do something like this:
SELECT g FROM Group g WHERE g = :group OR g.parent = :group
...so that doing:
query.setParameter("group", theGroup);
will populate both fields. Is this possible?
I realize I could just run this and see, but I figured that asking first might save me (and anyone else who happens to find this question) a bit of time and frustration.
Yes, it's part of the spec. Makes no sense for a spec to insist on passing in an extra param name with dup value
I am trying to come up with a design for a method that takes another method as a parameter and retrieves the parameter values of the method passed. How can this be done? I've tried using java.lang.reflect.* but can't seem to find an API that supports this.
You can't really get the values passed as parameters like this.
You can make your own Proxy and from there capture parameters before calling the right method. Or with aspect you could get the parameters value directly when the method is called.
Method.getParameterTypes
http://download.oracle.com/javase/1.4.2/docs/api/java/lang/reflect/Method.html#getParameterTypes%28%29