org.apache.flink.api.java.utils

Class RequiredParameters

java.lang.Object

org.apache.flink.api.java.utils.RequiredParameters

@PublicEvolving
public class RequiredParameters
extends Object

Facility to manage required parameters in user defined functions.

Constructor Summary

Constructors

Constructor and Description
RequiredParameters()

Method Summary

Modifier and Type	Method and Description
void	add(Option option) Add a parameter encapsulated in an Option object.
Option	add(String name) Add a parameter based on its name.
ParameterTool	applyTo(ParameterTool parameterTool) Check for all required parameters defined: - has a value been passed - if not, does the parameter have an associated default value - does the type of the parameter match the one defined in RequiredParameters - does the value provided in the parameterTool adhere to the choices defined in the option.
String	getHelp() Build a help text for the defined parameters.
String	getHelp(List<String> missingArguments) Build a help text for the defined parameters and list the missing arguments at the end of the text.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RequiredParameters

public RequiredParameters()

Method Detail

add

public Option add(String name)
           throws RequiredParametersException

Add a parameter based on its name.

Parameters:

name - - the name of the parameter

Returns:

- an Option object representing the parameter

Throws:

RequiredParametersException - if an option with the same name is already defined

add

public void add(Option option)
         throws RequiredParametersException

Add a parameter encapsulated in an Option object.

Parameters:

option - - the parameter

Throws:

RequiredParametersException - if an option with the same name is already defined

applyTo

public ParameterTool applyTo(ParameterTool parameterTool)
                      throws RequiredParametersException

Check for all required parameters defined: - has a value been passed - if not, does the parameter have an associated default value - does the type of the parameter match the one defined in RequiredParameters - does the value provided in the parameterTool adhere to the choices defined in the option.

If any check fails, a RequiredParametersException is thrown

Parameters:

parameterTool - - parameters supplied by the user.

Returns:

the updated ParameterTool containing all the required parameters

Throws:

RequiredParametersException - if any of the specified checks fail

getHelp

public String getHelp()

Build a help text for the defined parameters.

The format of the help text will be: Required Parameters: \t -:shortName:, --:name: \t :helpText: \t default: :defaultValue: \t choices: :choices: \n

Returns:

a formatted help String.

getHelp

public String getHelp(List<String> missingArguments)

Build a help text for the defined parameters and list the missing arguments at the end of the text.

The format of the help text will be: Required Parameters: \t -:shortName:, --:name: \t :helpText: \t default: :defaultValue: \t choices: :choices: \n

Missing parameters: \t param1 param2 ... paramN

Parameters:

missingArguments - - a list of missing parameters

Returns:

a formatted help String.