Holder classes

Example: OUTPUT and INPUT-OUTPUT holder class

// Holder Definition
Public class Holder
{    public Holder();
    public Holder(Object value);
    public void setValue(Object value);
    public Object getValue();
    public boolean isNull();
}

This class has two constructors, one that does and one that does not set a value for the parameter. For an OUTPUT parameter, you do not need to set a value in the holder object. For an INPUT-OUTPUT parameter, you typically do need to set a value to pass as input in the holder object. You can also set the value using the setValue() method after the holder is created.

For an INPUT-OUTPUT parameter, you can set an input value to the ABL Unknown value (?) by calling setValue(null) on the holder object. For INPUT-OUTPUT and OUTPUT parameters, the application can find out whether an unknown output value is returned by calling the isNull() method or testing for a null return value from the getValue() method on the holder object.

For each parameter data type extension, the holder class and method names change as follows:

Syntax

Public class DataTypeNameHolder
{    public DataTypeNameHolder();
    public DataTypeNameHolder(DataType value);
    public void setDataTypeNameValue(DataType value);
    public Object getDataTypeNameValue();
}

DataTypeName is an initial upper-case name that closely matches the short intrinsic data type or class name for the value, and DataType is the exact primitive data type or full Java class name (with no changes in letter case).

The following table shows the ABL-to-Java mapping of INPUT-OUTPUT and OUTPUT parameters to specific holder classes.

The following table shows the ABL array-to-Java mapping of INPUT-OUTPUT and OUTPUT array parameters to specific holder classes.