Multiple if statements modifying private fields

I have a class A defined as follows in Java:

public class A
{
    private String fieldName;
    private String detailFieldName;
    private String externalFieldName;
    private int formatLength;
    /* additional private members */

    void setProperty( String aPropertyName, String aPropertyValue )
    {
        try
        {
            if( aPropertyName.equals( AField.FieldName.getName() ) )
            {
                fieldName = aPropertyValue;
                return;
            }
            if( aPropertyName.equals( AField.DetailFieldName.getName() ) )
            {
                detailFieldName = aPropertyValue;
                return;
            }
            if( aPropertyName.equals( AField.ExternalFieldName.getName() ) )
            {
                externalFieldName = aPropertyValue;
                return;
            }
            if( aPropertyName.equals( AField.FormatLength.getName() ) )
            {
                formatLength = Integer.parseInt( aPropertyValue );
                return;
            }
            /* more if's */
        }
        catch( Exception e )
        {
            /* logging exceptions */
        }
    }
}

The further if's are analogical, i.e. they all modify one specific private member variable of the class A.

The AField is defined as follows:

public enum AField
{
    FieldName( "FieldName" ),
    DetailFieldName( "DetailViewFieldName" ),
    ExternalFieldName( "ExternalFieldName" ),
    FormatLength( "FormatLength" )
    /* more fields */

    private final String name;

    AField(String aName)
    {
        name = aName;
    }

    public String getName()
    {
        return name;
    }
}

I would like to replace the multiple if..return.. statements with the more appropriate, and easier to maintain solution. I read about using the map with each AField value as a key and a proper command (Command design pattern) as a value. However, my problem here is that in each of the if statements I modify one of the A's class private members and in order to do that I must have access to them.

What kind of a solution can you suggest? Thanks in advance.