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| Chapter 11 Scrolling |

## 11.3 The Adjustable Interface

The `Adjustable` interface is new to Java 1.1. It provides the method signatures required for an object that lets you adjust a bounded integer value. It is currently implemented by `Scrollbar` and returned by two methods within `ScrollPane`.

### Constants of the Adjustable Interface

There are two direction specifiers for `Adjustable`.

public final static int HORIZONTAL

  `HORIZONTAL` is the constant for horizontal orientation.

public final static int VERTICAL

  `VERTICAL` is the constant for vertical orientation.

### Methods of the Adjustable Interface

public abstract int getOrientation ()

  The `getOrientation()` method is for returning the current orientation of the adjustable object, either `Adjustable.HORIZONTAL` or `Adjustable.VERTICAL`.

  `setOrientation()` is not part of the interface. Not all adjustable objects need to be able to alter orientation. For example, `Scrollbar` instances can change their orientation, but each `Adjustable` instance associated with a `ScrollPane` has a fixed, unchangeable orientation.

public abstract int getVisibleAmount ()

  The `getVisibleAmount()` method lets you retrieve the size of the visible slider of the adjustable object.

public abstract void setVisibleAmount (int amount)

  The `setVisibleAmount()` method lets you change the size of the visible slider to `amount`.

public abstract int getValue ()

  The `getValue()` method lets you retrieve the current value of the adjustable object.

public abstract void setValue (int value)

  The `setValue()` method lets you change the value of the adjustable object to `value`.

public abstract int getMinimum ()

  The `getMinimum()` method lets you retrieve the current minimum setting for the object.

public abstract void setMinimum (int minimum)

  The `setMinimum()` method lets you change the minimum value of the adjustable object to `minimum`.

public abstract int getMaximum ()

  The `getMaximum()` method lets you retrieve the current maximum setting for the object.

public abstract void setMaximum (int maximum)

  The `setMaximum()` method lets you change the maximum value of the adjustable object to `maximum`.

public abstract int getUnitIncrement ()

  The `getUnitIncrement()` method lets you retrieve the current line increment.

public abstract void setUnitIncrement (int amount)

  The `setUnitIncrement()` method lets you change the line increment amount of the adjustable object to `amount`.

public abstract int getBlockIncrement ()

  The `getBlockIncrement()` method lets you retrieve the current page increment.

public abstract void setBlockIncrement (int amount)

  The `setBlockIncrement()` method lets you change the paging increment amount of the adjustable object to `amount`.

public abstract void addAdjustmentListener(AdjustmentListener listener)

  The `addAdjustmentListener()` method lets you register `listener` as an object interested in being notified when an `AdjustmentEvent` passes through the `EventQueue` with this `Adjustable` object as its target.

public abstract void removeAdjustmentListener(ItemListener listener)

  The `removeAdjustmentListener()` method removes `listener` as a interested listener. If `listener` is not registered, nothing happens.

Scrolling An Image |  | ScrollPane