public ListELResolver() 
{
        this.isReadOnly = false;
}

Creates a new read/write ListELResolver.

 public ListELResolver(boolean isReadOnly) 
{
        this.isReadOnly = isReadOnly;
}

Creates a new ListELResolver whose read-only status is determined by the given parameter.

Parameters:

isReadOnly - true if this resolver cannot modify lists; false otherwise.

 public Class getCommonPropertyType(ELContext context,
    Object base) 
{
        if (base != null && base instanceof List) {
            return Integer.class;
        }
        return null;
}

If the base object is a list, returns the most general type that this resolver accepts for the property argument. Otherwise, returns null.

Assuming the base is a List, this method will always return Integer.class. This is because Lists accept integers as their index.

 public Iterator getFeatureDescriptors(ELContext context,
    Object base) 
{
        return null;
}

Always returns null, since there is no reason to iterate through set set of all integers.

The #getCommonPropertyType method returns sufficient information about what properties this resolver accepts.

 public Class getType(ELContext context,
    Object base,
    Object property) 
{
        if (context == null) {
            throw new NullPointerException();
        }
        if (base != null && base instanceof List) {
            context.setPropertyResolved(true);
            List list = (List) base;
            int index = toInteger(property);
            if (index <  0 || index  >= list.size()) {
                throw new PropertyNotFoundException();
            } 
            return Object.class;
        }
        return null;
}

If the base object is a list, returns the most general acceptable type for a value in this list.

If the base is a List, the propertyResolved property of the ELContext object must be set to true by this resolver, before returning. If this property is not true after this method is called, the caller should ignore the return value.

Assuming the base is a List, this method will always return Object.class. This is because Lists accept any object as an element.

 public Object getValue(ELContext context,
    Object base,
    Object property) 
{
        if (context == null) {
            throw new NullPointerException();
        }
        if (base != null && base instanceof List) {
            context.setPropertyResolved(true);
            List list = (List) base;
            int index = toInteger(property);
            if (index <  0 || index  >= list.size()) {
                return null;
            } 
            return list.get(index);
        }
        return null;
}

If the base object is a list, returns the value at the given index. The index is specified by the property argument, and coerced into an integer. If the coercion could not be performed, an IllegalArgumentException is thrown. If the index is out of bounds, null is returned.

If the base is a List, the propertyResolved property of the ELContext object must be set to true by this resolver, before returning. If this property is not true after this method is called, the caller should ignore the return value.

 public boolean isReadOnly(ELContext context,
    Object base,
    Object property) 
{
                                                                                                                                                                                                                                                                                                                               
        if (context == null) {
            throw new NullPointerException();
        }
        if (base != null && base instanceof List) {
            context.setPropertyResolved(true);
            List list = (List) base;
            int index = toInteger(property);
            if (index <  0 || index  >= list.size()) {
                throw new PropertyNotFoundException();
            } 
            return list.getClass() == theUnmodifiableListClass || isReadOnly;
        }
        return false;
}

If the base object is a list, returns whether a call to #setValue will always fail.

If the base is a List, the propertyResolved property of the ELContext object must be set to true by this resolver, before returning. If this property is not true after this method is called, the caller should ignore the return value.

If this resolver was constructed in read-only mode, this method will always return true.

If a List was created using java.util.Collections#unmodifiableList , this method must return true. Unfortunately, there is no Collections API method to detect this. However, an implementation can create a prototype unmodifiable List and query its runtime type to see if it matches the runtime type of the base object as a workaround.

 public  void setValue(ELContext context,
    Object base,
    Object property,
    Object val) 
{
        if (context == null) {
            throw new NullPointerException();
        }
        if (base != null && base instanceof List) {
            context.setPropertyResolved(true);
            List list = (List) base;
            int index = toInteger(property);
            if (isReadOnly) {
                throw new PropertyNotWritableException();
            }
            try {
                list.set(index, val);
            } catch (UnsupportedOperationException ex) {
                throw new PropertyNotWritableException();
            } catch (IndexOutOfBoundsException ex) {
                throw new PropertyNotFoundException();
            } catch (ClassCastException ex) {
                throw ex;
            } catch (NullPointerException ex) {
                throw ex;
            } catch (IllegalArgumentException ex) {
                throw ex;
            }
        }
}

If the base object is a list, attempts to set the value at the given index with the given value. The index is specified by the property argument, and coerced into an integer. If the coercion could not be performed, an IllegalArgumentException is thrown. If the index is out of bounds, a PropertyNotFoundException is thrown.

If the base is a List, the propertyResolved property of the ELContext object must be set to true by this resolver, before returning. If this property is not true after this method is called, the caller can safely assume no value was set.

If this resolver was constructed in read-only mode, this method will always throw PropertyNotWritableException.

If a List was created using java.util.Collections#unmodifiableList , this method must throw PropertyNotWritableException. Unfortunately, there is no Collections API method to detect this. However, an implementation can create a prototype unmodifiable List and query its runtime type to see if it matches the runtime type of the base object as a workaround.