com.amazonaws.services.dynamodbv2.model

## クラス ExpectedAttributeValue

- java.lang.Object
- - com.amazonaws.services.dynamodbv2.model.ExpectedAttributeValue

- すべての実装されたインタフェース:
    java.io.Serializable

      public class ExpectedAttributeValue
      extends java.lang.Object
      implements java.io.Serializable

  An attribute value used with conditional DeleteItem , PutItem or UpdateItem operations. Amazon DynamoDB will check to see if the attribute value already exists; or if the attribute exists and has a particular value before updating it.

  関連項目:
    直列化された形式

- - ### コンストラクタの概要

    コンストラクタ
    コンストラクタと説明
    `ExpectedAttributeValue()` Default constructor for a new ExpectedAttributeValue object.
    `ExpectedAttributeValue(AttributeValue value)` Constructs a new ExpectedAttributeValue object.
    `ExpectedAttributeValue(java.lang.Boolean exists)` Constructs a new ExpectedAttributeValue object.

  - ### メソッドの概要

    メソッド
    修飾子とタイプ | メソッドと説明
    --- | ---
    `boolean` | `equals(java.lang.Object obj)`
    `java.lang.Boolean` | `getExists()` Causes Amazon DynamoDB to evaluate the value before attempting a conditional operation: If Exists is `true`, Amazon DynamoDB will check to see if that attribute value already exists in the table.
    `AttributeValue` | `getValue()` Represents the data for an attribute.
    `int` | `hashCode()`
    `java.lang.Boolean` | `isExists()` Causes Amazon DynamoDB to evaluate the value before attempting a conditional operation: If Exists is `true`, Amazon DynamoDB will check to see if that attribute value already exists in the table.
    `void` | `setExists(java.lang.Boolean exists)` Causes Amazon DynamoDB to evaluate the value before attempting a conditional operation: If Exists is `true`, Amazon DynamoDB will check to see if that attribute value already exists in the table.
    `void` | `setValue(AttributeValue value)` Represents the data for an attribute.
    `java.lang.String` | `toString()` Returns a string representation of this object; useful for testing and debugging.
    `ExpectedAttributeValue` | `withExists(java.lang.Boolean exists)` Causes Amazon DynamoDB to evaluate the value before attempting a conditional operation: If Exists is `true`, Amazon DynamoDB will check to see if that attribute value already exists in the table.
    `ExpectedAttributeValue` | `withValue(AttributeValue value)` Represents the data for an attribute.

    - ### クラスから継承されたメソッド java.lang.Object

      `clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

- - ### コンストラクタの詳細

    - #### ExpectedAttributeValue

          public ExpectedAttributeValue()

      Default constructor for a new ExpectedAttributeValue object. Callers should use the setter or fluent setter (with...) methods to initialize this object after creating it.

    - #### ExpectedAttributeValue

          public ExpectedAttributeValue(AttributeValue value)

      Constructs a new ExpectedAttributeValue object. Callers should use the setter or fluent setter (with...) methods to initialize any additional object members.
      パラメータ:
        `value` - Represents the data for an attribute. You can set one, and only one, of the elements.

    - #### ExpectedAttributeValue

          public ExpectedAttributeValue(java.lang.Boolean exists)

      Constructs a new ExpectedAttributeValue object. Callers should use the setter or fluent setter (with...) methods to initialize any additional object members.
      パラメータ:
        `exists` - Causes Amazon DynamoDB to evaluate the value before attempting a conditional operation:

        - If Exists is `true`, Amazon DynamoDB will check to see if that attribute value already exists in the table. If it is found, then the operation succeeds. If it is not found, the operation fails with a ConditionalCheckFailedException.

        - If Exists is `false`, Amazon DynamoDB assumes that the attribute value does not exist in the table. If in fact the value does not exist, then the assumption is valid and the operation succeeds. If the value is found, despite the assumption that it does not exist, the operation fails with a ConditionalCheckFailedException.

        The default setting for Exists is `true`. If you supply a Value all by itself, Amazon DynamoDB assumes the attribute exists: You don't have to set Exists to `true`, because it is implied.

        Amazon DynamoDB returns a ValidationException if:

        - Exists is `true` but there is no Value to check. (You expect a value to exist, but don't specify what that value is.)

        - Exists is `false` but you also specify a Value. (You cannot expect an attribute to have a value, while also expecting it not to exist.)

        If you specify more than one condition for Exists, then all of the conditions must evaluate to true. (In other words, the conditions are ANDed together.) Otherwise, the conditional operation will fail.

  - ### メソッドの詳細

    - #### getValue

          public AttributeValue getValue()

      Represents the data for an attribute. You can set one, and only one, of the elements.
      戻り値:
        Represents the data for an attribute. You can set one, and only one, of the elements.

    - #### setValue

          public void setValue(AttributeValue value)

      Represents the data for an attribute. You can set one, and only one, of the elements.
      パラメータ:
        `value` - Represents the data for an attribute. You can set one, and only one, of the elements.

    - #### withValue

          public ExpectedAttributeValue withValue(AttributeValue value)

      Represents the data for an attribute. You can set one, and only one, of the elements.

      Returns a reference to this object so that method calls can be chained together.

      パラメータ:
        `value` - Represents the data for an attribute. You can set one, and only one, of the elements.

    - #### isExists

          public java.lang.Boolean isExists()

      Causes Amazon DynamoDB to evaluate the value before attempting a conditional operation:

      - If Exists is `true`, Amazon DynamoDB will check to see if that attribute value already exists in the table. If it is found, then the operation succeeds. If it is not found, the operation fails with a ConditionalCheckFailedException.

      - If Exists is `false`, Amazon DynamoDB assumes that the attribute value does not exist in the table. If in fact the value does not exist, then the assumption is valid and the operation succeeds. If the value is found, despite the assumption that it does not exist, the operation fails with a ConditionalCheckFailedException.

      The default setting for Exists is `true`. If you supply a Value all by itself, Amazon DynamoDB assumes the attribute exists: You don't have to set Exists to `true`, because it is implied.

      Amazon DynamoDB returns a ValidationException if:

      - Exists is `true` but there is no Value to check. (You expect a value to exist, but don't specify what that value is.)

      - Exists is `false` but you also specify a Value. (You cannot expect an attribute to have a value, while also expecting it not to exist.)

      If you specify more than one condition for Exists, then all of the conditions must evaluate to true. (In other words, the conditions are ANDed together.) Otherwise, the conditional operation will fail.

      戻り値:
        Causes Amazon DynamoDB to evaluate the value before attempting a conditional operation:

        - If Exists is `true`, Amazon DynamoDB will check to see if that attribute value already exists in the table. If it is found, then the operation succeeds. If it is not found, the operation fails with a ConditionalCheckFailedException.

        - If Exists is `false`, Amazon DynamoDB assumes that the attribute value does not exist in the table. If in fact the value does not exist, then the assumption is valid and the operation succeeds. If the value is found, despite the assumption that it does not exist, the operation fails with a ConditionalCheckFailedException.

        The default setting for Exists is `true`. If you supply a Value all by itself, Amazon DynamoDB assumes the attribute exists: You don't have to set Exists to `true`, because it is implied.

        Amazon DynamoDB returns a ValidationException if:

        - Exists is `true` but there is no Value to check. (You expect a value to exist, but don't specify what that value is.)

        - Exists is `false` but you also specify a Value. (You cannot expect an attribute to have a value, while also expecting it not to exist.)

        If you specify more than one condition for Exists, then all of the conditions must evaluate to true. (In other words, the conditions are ANDed together.) Otherwise, the conditional operation will fail.

    - #### setExists

          public void setExists(java.lang.Boolean exists)

      Causes Amazon DynamoDB to evaluate the value before attempting a conditional operation:

      - If Exists is `true`, Amazon DynamoDB will check to see if that attribute value already exists in the table. If it is found, then the operation succeeds. If it is not found, the operation fails with a ConditionalCheckFailedException.

      - If Exists is `false`, Amazon DynamoDB assumes that the attribute value does not exist in the table. If in fact the value does not exist, then the assumption is valid and the operation succeeds. If the value is found, despite the assumption that it does not exist, the operation fails with a ConditionalCheckFailedException.

      The default setting for Exists is `true`. If you supply a Value all by itself, Amazon DynamoDB assumes the attribute exists: You don't have to set Exists to `true`, because it is implied.

      Amazon DynamoDB returns a ValidationException if:

      - Exists is `true` but there is no Value to check. (You expect a value to exist, but don't specify what that value is.)

      - Exists is `false` but you also specify a Value. (You cannot expect an attribute to have a value, while also expecting it not to exist.)

      If you specify more than one condition for Exists, then all of the conditions must evaluate to true. (In other words, the conditions are ANDed together.) Otherwise, the conditional operation will fail.

      パラメータ:
        `exists` - Causes Amazon DynamoDB to evaluate the value before attempting a conditional operation:

        - If Exists is `true`, Amazon DynamoDB will check to see if that attribute value already exists in the table. If it is found, then the operation succeeds. If it is not found, the operation fails with a ConditionalCheckFailedException.

        - If Exists is `false`, Amazon DynamoDB assumes that the attribute value does not exist in the table. If in fact the value does not exist, then the assumption is valid and the operation succeeds. If the value is found, despite the assumption that it does not exist, the operation fails with a ConditionalCheckFailedException.

        The default setting for Exists is `true`. If you supply a Value all by itself, Amazon DynamoDB assumes the attribute exists: You don't have to set Exists to `true`, because it is implied.

        Amazon DynamoDB returns a ValidationException if:

        - Exists is `true` but there is no Value to check. (You expect a value to exist, but don't specify what that value is.)

        - Exists is `false` but you also specify a Value. (You cannot expect an attribute to have a value, while also expecting it not to exist.)

        If you specify more than one condition for Exists, then all of the conditions must evaluate to true. (In other words, the conditions are ANDed together.) Otherwise, the conditional operation will fail.

    - #### withExists

          public ExpectedAttributeValue withExists(java.lang.Boolean exists)

      Causes Amazon DynamoDB to evaluate the value before attempting a conditional operation:

      - If Exists is `true`, Amazon DynamoDB will check to see if that attribute value already exists in the table. If it is found, then the operation succeeds. If it is not found, the operation fails with a ConditionalCheckFailedException.

      - If Exists is `false`, Amazon DynamoDB assumes that the attribute value does not exist in the table. If in fact the value does not exist, then the assumption is valid and the operation succeeds. If the value is found, despite the assumption that it does not exist, the operation fails with a ConditionalCheckFailedException.

      The default setting for Exists is `true`. If you supply a Value all by itself, Amazon DynamoDB assumes the attribute exists: You don't have to set Exists to `true`, because it is implied.

      Amazon DynamoDB returns a ValidationException if:

      - Exists is `true` but there is no Value to check. (You expect a value to exist, but don't specify what that value is.)

      - Exists is `false` but you also specify a Value. (You cannot expect an attribute to have a value, while also expecting it not to exist.)

      If you specify more than one condition for Exists, then all of the conditions must evaluate to true. (In other words, the conditions are ANDed together.) Otherwise, the conditional operation will fail.

      Returns a reference to this object so that method calls can be chained together.

      パラメータ:
        `exists` - Causes Amazon DynamoDB to evaluate the value before attempting a conditional operation:

        - If Exists is `true`, Amazon DynamoDB will check to see if that attribute value already exists in the table. If it is found, then the operation succeeds. If it is not found, the operation fails with a ConditionalCheckFailedException.

        - If Exists is `false`, Amazon DynamoDB assumes that the attribute value does not exist in the table. If in fact the value does not exist, then the assumption is valid and the operation succeeds. If the value is found, despite the assumption that it does not exist, the operation fails with a ConditionalCheckFailedException.

        The default setting for Exists is `true`. If you supply a Value all by itself, Amazon DynamoDB assumes the attribute exists: You don't have to set Exists to `true`, because it is implied.

        Amazon DynamoDB returns a ValidationException if:

        - Exists is `true` but there is no Value to check. (You expect a value to exist, but don't specify what that value is.)

        - Exists is `false` but you also specify a Value. (You cannot expect an attribute to have a value, while also expecting it not to exist.)

        If you specify more than one condition for Exists, then all of the conditions must evaluate to true. (In other words, the conditions are ANDed together.) Otherwise, the conditional operation will fail.

    - #### getExists

          public java.lang.Boolean getExists()

      Causes Amazon DynamoDB to evaluate the value before attempting a conditional operation:

      - If Exists is `true`, Amazon DynamoDB will check to see if that attribute value already exists in the table. If it is found, then the operation succeeds. If it is not found, the operation fails with a ConditionalCheckFailedException.

      - If Exists is `false`, Amazon DynamoDB assumes that the attribute value does not exist in the table. If in fact the value does not exist, then the assumption is valid and the operation succeeds. If the value is found, despite the assumption that it does not exist, the operation fails with a ConditionalCheckFailedException.

      The default setting for Exists is `true`. If you supply a Value all by itself, Amazon DynamoDB assumes the attribute exists: You don't have to set Exists to `true`, because it is implied.

      Amazon DynamoDB returns a ValidationException if:

      - Exists is `true` but there is no Value to check. (You expect a value to exist, but don't specify what that value is.)

      - Exists is `false` but you also specify a Value. (You cannot expect an attribute to have a value, while also expecting it not to exist.)

      If you specify more than one condition for Exists, then all of the conditions must evaluate to true. (In other words, the conditions are ANDed together.) Otherwise, the conditional operation will fail.

      戻り値:
        Causes Amazon DynamoDB to evaluate the value before attempting a conditional operation:

        - If Exists is `true`, Amazon DynamoDB will check to see if that attribute value already exists in the table. If it is found, then the operation succeeds. If it is not found, the operation fails with a ConditionalCheckFailedException.

        - If Exists is `false`, Amazon DynamoDB assumes that the attribute value does not exist in the table. If in fact the value does not exist, then the assumption is valid and the operation succeeds. If the value is found, despite the assumption that it does not exist, the operation fails with a ConditionalCheckFailedException.

        The default setting for Exists is `true`. If you supply a Value all by itself, Amazon DynamoDB assumes the attribute exists: You don't have to set Exists to `true`, because it is implied.

        Amazon DynamoDB returns a ValidationException if:

        - Exists is `true` but there is no Value to check. (You expect a value to exist, but don't specify what that value is.)

        - Exists is `false` but you also specify a Value. (You cannot expect an attribute to have a value, while also expecting it not to exist.)

        If you specify more than one condition for Exists, then all of the conditions must evaluate to true. (In other words, the conditions are ANDed together.) Otherwise, the conditional operation will fail.

    - #### toString

          public java.lang.String toString()

      Returns a string representation of this object; useful for testing and debugging.
      オーバーライド:
        `toString` クラス内 `java.lang.Object`
      戻り値:
        A string representation of this object.
      関連項目:
        `Object.toString()`

    - #### hashCode

          public int hashCode()

      オーバーライド:
        `hashCode` クラス内 `java.lang.Object`

    - #### equals

          public boolean equals(java.lang.Object obj)

      オーバーライド:
        `equals` クラス内 `java.lang.Object`