## Input

### Description

Allows user interaction during the build process by prompting for input. To do so, it uses the configured InputHandler.

The prompt can be set via the message attribute or as character data nested into the element.

Optionally a set of valid input arguments can be defined via the validargs attribute. `Input` task will not accept a value that doesn't match one of the predefined.

Optionally a property can be created from the value entered by the user. This property can then be used during the following build run. `Input` then behaves as property task which means that existing properties cannot be overridden. Since Apache Ant 1.6, `<input>` will not prompt for input if a property should be set by the task that has already been set in the project (and the task wouldn't have any effect).

Historically, a regular complaint about this task has been that it echoes characters to the console, this is a critical security defect, we must fix it immediately, etc, etc. This problem was due to the lack in early versions of Java of a (fully functional) facility for handling secure console input. In Java 6 that shortcoming in Java's API was addressed and Ant versions 1.7.1 and 1.8 have added support for Java 6 secure console input feature (see handler type).

IDE behaviour depends upon the IDE: some hang waiting for input, some let you type it in. For this situation, place the password in a (secured) property file and load in before the `input` task.

### Parameters

Attribute | Description | Required
--- | --- | ---
message | the Message which gets displayed to the user during the build run. | No
validargs | comma separated String containing valid input arguments. If set, `input` task will reject any input not defined here. Comparison of input to validargs is case sensitive. If you want a and A to be accepted you will need to define both arguments within validargs. | No
addproperty | the name of a property to be created from input. Behaviour is equal to property task which means that existing properties cannot be overridden. | No
defaultvalue | Defines the default value of the property to be created from input. Property value will be set to default if no input is received. | No

### Parameters specified as nested elements

#### Handler

Since Ant 1.7, a nested `<handler>` element can be used to specify an `InputHandler`, so that different `InputHandler`s may be used among different `Input` tasks.

Attribute | Description | Required
--- | --- | ---
type | one of default, propertyfile, greedy, or secure (since Ant 1.8). | One of these
refid | Reference to an `InputHandler` defined elsewhere in the project.
classname | The name of an `InputHandler` subclass.
classpath | The classpath to use with classname. | No
classpathref | The refid of a classpath to use with classname. | No
loaderref | The refid of a classloader to use with classname. | No

The classpath can also be specified by means of one or more nested `<classpath>` elements.

### Examples

    <input/>

Will pause the build run until return key is pressed when using the default InputHandler, the concrete behavior is defined by the `InputHandler` implementation you use.

    <input>Press Return key to continue...</input>

Will display the message Press Return key to continue... and pause the build run until return key is pressed (again, the concrete behavior is implementation dependent).

    <input message="Press Return key to continue..."/>

Will display the message Press Return key to continue... and pause the build run until return key is pressed (see above).

    <input message="All data is going to be deleted from DB continue (y/n)?"
           validargs="y,n"
           addproperty="do.delete"/>
    <condition property="do.abort">
      <equals arg1="n" arg2="${do.delete}"/>
    </condition>
    <fail if="do.abort">Build aborted by user.</fail>

Will display the message All data is going to be deleted from DB continue (y/n)? and require y to continue build or n to exit build with following message Build aborted by user..

    <input message="Please enter db-username:"
           addproperty="db.user"/>

Will display the message Please enter db-username: and set the property `db.user` to the value entered by the user.

    <input message="Please enter db-username:"
           addproperty="db.user"
           defaultvalue="Scott-Tiger"/>

Same as above, but will set `db.user` to the value Scott-Tiger if the user enters no value (simply presses return).