SimpleScriptContext (Java Platform SE 8 )
Keywords: javax.script.SimpleScriptContext class
Date: 2023-01-18

compact1, compact2, compact3
javax.script

## Class SimpleScriptContext

- java.lang.Object
- - javax.script.SimpleScriptContext

- All Implemented Interfaces:
    ScriptContext

      public class SimpleScriptContext
      extends Object
      implements ScriptContext

  Simple implementation of ScriptContext.
  Since:
    1.6

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected Bindings` | `engineScope` This is the engine scope bindings.
    `protected Writer` | `errorWriter` This is the writer to be used to output errors from scripts.
    `protected Bindings` | `globalScope` This is the global scope bindings.
    `protected Reader` | `reader` This is the reader to be used for input from scripts.
    `protected Writer` | `writer` This is the writer to be used to output from scripts.

    - ### Fields inherited from interface javax.script.ScriptContext

      `ENGINE_SCOPE, GLOBAL_SCOPE`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `SimpleScriptContext()` Create a `SimpleScriptContext`.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `Object` | `getAttribute(String name)` Retrieves the value of the attribute with the given name in the scope occurring earliest in the search order.
    `Object` | `getAttribute(String name, int scope)` Gets the value of an attribute in a given scope.
    `int` | `getAttributesScope(String name)` Get the lowest scope in which an attribute is defined.
    `Bindings` | `getBindings(int scope)` Returns the value of the `engineScope` field if specified scope is `ENGINE_SCOPE`.
    `Writer` | `getErrorWriter()` Returns the `Writer` used to display error output.
    `Reader` | `getReader()` Returns a `Reader` to be used by the script to read input.
    `List<Integer>` | `getScopes()` Returns immutable `List` of all the valid values for scope in the ScriptContext.
    `Writer` | `getWriter()` Returns the `Writer` for scripts to use when displaying output.
    `Object` | `removeAttribute(String name, int scope)` Remove an attribute in a given scope.
    `void` | `setAttribute(String name, Object value, int scope)` Sets the value of an attribute in a given scope.
    `void` | `setBindings(Bindings bindings, int scope)` Sets a `Bindings` of attributes for the given scope.
    `void` | `setErrorWriter(Writer writer)` Sets the `Writer` used to display error output.
    `void` | `setReader(Reader reader)` Sets the `Reader` for scripts to read input .
    `void` | `setWriter(Writer writer)` Sets the `Writer` for scripts to use when displaying output.

    - ### Methods inherited from class java.lang.Object

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

- - ### Field Detail

    - #### writer

          protected Writer writer

      This is the writer to be used to output from scripts. By default, a `PrintWriter` based on `System.out` is used. Accessor methods getWriter, setWriter are used to manage this field.
      See Also:
        `System.out`, `PrintWriter`

    - #### errorWriter

          protected Writer errorWriter

      This is the writer to be used to output errors from scripts. By default, a `PrintWriter` based on `System.err` is used. Accessor methods getErrorWriter, setErrorWriter are used to manage this field.
      See Also:
        `System.err`, `PrintWriter`

    - #### reader

          protected Reader reader

      This is the reader to be used for input from scripts. By default, a `InputStreamReader` based on `System.in` is used and default charset is used by this reader. Accessor methods getReader, setReader are used to manage this field.
      See Also:
        `System.in`, `InputStreamReader`

    - #### engineScope

          protected Bindings engineScope

      This is the engine scope bindings. By default, a `SimpleBindings` is used. Accessor methods setBindings, getBindings are used to manage this field.
      See Also:
        `SimpleBindings`

    - #### globalScope

          protected Bindings globalScope

      This is the global scope bindings. By default, a null value (which means no global scope) is used. Accessor methods setBindings, getBindings are used to manage this field.

  - ### Constructor Detail

    - #### SimpleScriptContext

          public SimpleScriptContext()

      Create a `SimpleScriptContext`.

  - ### Method Detail

    - #### setBindings

          public void setBindings(Bindings bindings,
                                  int scope)

      Sets a `Bindings` of attributes for the given scope. If the value of scope is `ENGINE_SCOPE` the given `Bindings` replaces the `engineScope` field. If the value of scope is `GLOBAL_SCOPE` the given `Bindings` replaces the `globalScope` field.
      Specified by:
        `setBindings` in interface `ScriptContext`
      Parameters:
        `bindings` - The `Bindings` of attributes to set.
        `scope` - The value of the scope in which the attributes are set.
      Throws:
        `IllegalArgumentException` - if scope is invalid.
        `NullPointerException` - if the value of scope is `ENGINE_SCOPE` and the specified `Bindings` is null.

    - #### getAttribute

          public Object getAttribute(String name)

      Retrieves the value of the attribute with the given name in the scope occurring earliest in the search order. The order is determined by the numeric value of the scope parameter (lowest scope values first.)
      Specified by:
        `getAttribute` in interface `ScriptContext`
      Parameters:
        `name` - The name of the the attribute to retrieve.
      Returns:
        The value of the attribute in the lowest scope for which an attribute with the given name is defined. Returns null if no attribute with the name exists in any scope.
      Throws:
        `NullPointerException` - if the name is null.
        `IllegalArgumentException` - if the name is empty.

    - #### getAttribute

          public Object getAttribute(String name,
                                     int scope)

      Gets the value of an attribute in a given scope.
      Specified by:
        `getAttribute` in interface `ScriptContext`
      Parameters:
        `name` - The name of the attribute to retrieve.
        `scope` - The scope in which to retrieve the attribute.
      Returns:
        The value of the attribute. Returns `null` is the name does not exist in the given scope.
      Throws:
        `IllegalArgumentException` - if the name is empty or if the value of scope is invalid.
        `NullPointerException` - if the name is null.

    - #### removeAttribute

          public Object removeAttribute(String name,
                                        int scope)

      Remove an attribute in a given scope.
      Specified by:
        `removeAttribute` in interface `ScriptContext`
      Parameters:
        `name` - The name of the attribute to remove
        `scope` - The scope in which to remove the attribute
      Returns:
        The removed value.
      Throws:
        `IllegalArgumentException` - if the name is empty or if the scope is invalid.
        `NullPointerException` - if the name is null.

    - #### setAttribute

          public void setAttribute(String name,
                                   Object value,
                                   int scope)

      Sets the value of an attribute in a given scope.
      Specified by:
        `setAttribute` in interface `ScriptContext`
      Parameters:
        `name` - The name of the attribute to set
        `value` - The value of the attribute
        `scope` - The scope in which to set the attribute
      Throws:
        `IllegalArgumentException` - if the name is empty or if the scope is invalid.
        `NullPointerException` - if the name is null.

    - #### getWriter

          public Writer getWriter()

      Returns the `Writer` for scripts to use when displaying output.
      Specified by:
        `getWriter` in interface `ScriptContext`
      Returns:
        The `Writer`.

    - #### getReader

          public Reader getReader()

      Returns a `Reader` to be used by the script to read input.
      Specified by:
        `getReader` in interface `ScriptContext`
      Returns:
        The `Reader`.

    - #### setReader

          public void setReader(Reader reader)

      Sets the `Reader` for scripts to read input .
      Specified by:
        `setReader` in interface `ScriptContext`
      Parameters:
        `reader` - The new `Reader`.

    - #### setWriter

          public void setWriter(Writer writer)

      Sets the `Writer` for scripts to use when displaying output.
      Specified by:
        `setWriter` in interface `ScriptContext`
      Parameters:
        `writer` - The new `Writer`.

    - #### getErrorWriter

          public Writer getErrorWriter()

      Returns the `Writer` used to display error output.
      Specified by:
        `getErrorWriter` in interface `ScriptContext`
      Returns:
        The `Writer`

    - #### setErrorWriter

          public void setErrorWriter(Writer writer)

      Sets the `Writer` used to display error output.
      Specified by:
        `setErrorWriter` in interface `ScriptContext`
      Parameters:
        `writer` - The `Writer`.

    - #### getAttributesScope

          public int getAttributesScope(String name)

      Get the lowest scope in which an attribute is defined.
      Specified by:
        `getAttributesScope` in interface `ScriptContext`
      Parameters:
        `name` - Name of the attribute .
      Returns:
        The lowest scope. Returns -1 if no attribute with the given name is defined in any scope.
      Throws:
        `NullPointerException` - if name is null.
        `IllegalArgumentException` - if name is empty.

    - #### getBindings

          public Bindings getBindings(int scope)

      Returns the value of the `engineScope` field if specified scope is `ENGINE_SCOPE`. Returns the value of the `globalScope` field if the specified scope is `GLOBAL_SCOPE`.
      Specified by:
        `getBindings` in interface `ScriptContext`
      Parameters:
        `scope` - The specified scope
      Returns:
        The value of either the `engineScope` or `globalScope` field.
      Throws:
        `IllegalArgumentException` - if the value of scope is invalid.

    - #### getScopes

          public List<Integer> getScopes()

      Returns immutable `List` of all the valid values for scope in the ScriptContext.
      Specified by:
        `getScopes` in interface `ScriptContext`
      Returns:
        list of scope values

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