Changing Number, String to more general type Object

[Amandeep Singh]

private Set<String> setContPackType;
private Set<Number> setGrossWgt;
private Set<String> setGrossWgtUom;
private Set<Number> setVol;
private Set<Number> setContPackQty;
private Set<String> setContPackUom;

changed to

private Set<Object> setContPackType;
private Set<Object> setGrossWgt;
private Set<Object> setGrossWgtUom;
private Set<Object> setVol;
private Set<Object> setContPackQty;
private Set<Object> setContPackUom;

because i have a common 1 method, which update's these Set's. it is basically iterator. part of code shown below.

for(Iterator<Object> ii = setType.iterator(); ii.hasNext();){

here i can specify only 1 type as Object.



Any idea's ?

[Ernest Friedman-Hill]

Ideas for what? Do you have a question?

[Amandeep Singh]

My real question is, would it be fine to represent either String or Number as 1 common type as Object as shown in my changed code.

[Steve Luke]

Amandeep Singh wrote:My real question is, would it be fine to represent either String or Number as 1 common type as Object as shown in my changed code.

You will be better off referring to the Sets using their proper types. In the method that needs the Iterator, pass them in as Set<? extends Object>:

package syntax;

import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

public class ToGenerifyOrNot
{
    public static void main(String[] args)
    {
        Set<String> strings = new HashSet<String>();
            strings.add("Hi"); strings.add("Hello");
        Set<Number> numbers = new HashSet<Number>();
            numbers.add(145); numbers.add(167.233);
        iterateOver(strings);
        iterateOver(numbers);

    }
    
    public static void iterateOver(Set<? extends Object> set)
    {
        for (Iterator<? extends Object> iter = set.iterator(); iter.hasNext(); )
        {
            Object obj = iter.next();
            System.out.println(obj);
        }
        
    }
}

So you can maintain type safety elsewhere.

[Amandeep Singh]

that is really great. thank you.

[Amandeep Singh]

i would prefer to use the enhanced for loop.

public static void iterateOver(Set<? extends Object> set)
    {
        for (Object iter : set )
        {
            System.out.println(iter);
        }

    }

now my question is, how to ensure the null check before using the enhanced for loop?

[Rob Spoor]

Do you mean this:

public static void iterateOver(Set<?> set)   
{
    if (set != null)   
    {
        for (Object iter : set )   
        {   
            System.out.println(iter);   
        }   
    }  
}

Note that I removed "extends Object". This is because "?" and "? extends Object" are basically the same since Object is the root of all class hierarchies. Similarly, if you ever see "? super Object" you can replace it with "Object".

[Amandeep Singh]

to check for null, traditional method. thanks

this is informative.

Note that I removed "extends Object". This is because "?" and "? extends Object" are basically the same since Object is the root of all class hierarchies. Similarly, if you ever see "? super Object" you can replace it with "Object".

you mean i should use objects only or ? .

public static void iterateOver(Set<?> set)

or

public static void iterateOver(Set<Objects> set)

[Amandeep Singh]

ok i tried the code. the first option works.