FieldAccessor (Flink : Runtime 2.0-preview1 API)

java.lang.Object
- org.apache.flink.streaming.util.typeutils.FieldAccessor<T,F>

All Implemented Interfaces:

Serializable
```
@Internal
public abstract class FieldAccessor<T,F>
extends Object
implements Serializable
```
These classes encapsulate the logic of accessing a field specified by the user as either an index or a field expression string. TypeInformation can also be requested for the field. The position index might specify a field of a Tuple, an array, or a simple type(only "0th field").
Field expressions that specify nested fields (e.g. "f1.a.foo") result in nested field accessors. These penetrate one layer, and then delegate the rest of the work to an "innerAccessor". (see PojoFieldAccessor, RecursiveTupleFieldAccessor, RecursiveProductFieldAccessor)

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type Field Description

protected org.apache.flink.api.common.typeinfo.TypeInformation fieldType

Constructor Summary

Constructors
Constructor Description

FieldAccessor()

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`abstract F`	`get(T record)`	Gets the value of the field (specified in the constructor) of the given record.
`org.apache.flink.api.common.typeinfo.TypeInformation<F>`	`getFieldType()`	Gets the TypeInformation for the type of the field.
`abstract T`	`set(T record, F fieldValue)`	Sets the field (specified in the constructor) of the given record to the given value.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - fieldType
```
protected org.apache.flink.api.common.typeinfo.TypeInformation fieldType
```
- Constructor Detail
  - FieldAccessor
```
public FieldAccessor()
```
- Method Detail
  - getFieldType
```
public org.apache.flink.api.common.typeinfo.TypeInformation<F> getFieldType()
```
    Gets the TypeInformation for the type of the field. Note: For an array of a primitive type, it returns the corresponding basic type (Integer for int[]).
  - get
```
public abstract F get(T record)
```
    Gets the value of the field (specified in the constructor) of the given record.
    
    Parameters:
    
    record - The record on which the field will be accessed
    
    Returns:
    
    The value of the field.
  - set
```
public abstract T set(T record,
                      F fieldValue)
```
    Sets the field (specified in the constructor) of the given record to the given value.
    Warning: This might modify the original object, or might return a new object instance. (This is necessary, because the record might be immutable.)
    
    Parameters:
    
    record - The record to modify
    
    fieldValue - The new value of the field
    
    Returns:
    
    A record that has the given field value. (this might be a new instance or the original)