item.html

是MIDP 的API 查詢文件, 大家可以看一下裡面的index.html, 再用Package 或 Class 名字來查.

<DT><B>Returns:</B><DD>a combination of layout directive values<DT><B>Since: </B><DD>MIDP 2.0</DD>
<DT><B>See Also: </B><DD><A HREF="../../../javax/microedition/lcdui/Item.html#setLayout(int)"><CODE>setLayout(int)</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="setLayout(int)"><!-- --></A><H3>
setLayout</H3>
<PRE>
public void <B>setLayout</B>(int&nbsp;layout)</PRE>
<DL>
<DD>Sets the layout directives for this item.

 <p>It is illegal to call this method if this <code>Item</code> 
 is contained within an <code>Alert</code>.</p><DD><DL>
<DT><B>Parameters:</B><DD><CODE>layout</CODE> - a combination of layout directive values for this item<DT><B>Throws:</B><DD><CODE><A HREF="../../../java/lang/IllegalArgumentException.html">IllegalArgumentException</A></CODE> - if the value of layout is not a
 bit-wise OR combination of layout directives<DD><CODE><A HREF="../../../java/lang/IllegalStateException.html">IllegalStateException</A></CODE> - if this <code>Item</code> is
 contained within an <code>Alert</code><DT><B>Since: </B><DD>MIDP 2.0</DD>
<DT><B>See Also: </B><DD><A HREF="../../../javax/microedition/lcdui/Item.html#getLayout()"><CODE>getLayout()</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="addCommand(javax.microedition.lcdui.Command)"><!-- --></A><H3>
addCommand</H3>
<PRE>
public void <B>addCommand</B>(<A HREF="../../../javax/microedition/lcdui/Command.html">Command</A>&nbsp;cmd)</PRE>
<DL>
<DD>Adds a context sensitive <code>Command</code> to the item.
 The semantic type of
 <code>Command</code> should be <code>ITEM</code>. The implementation
 will present the command
 only when the item is active, for example, highlighted.
 <p>
 If the added command is already in the item (tested by comparing the
 object references), the method has no effect. If the item is
 actually visible on the display, and this call affects the set of
 visible commands, the implementation should update the display as soon
 as it is feasible to do so.

 <p>It is illegal to call this method if this <code>Item</code>
 is contained within an <code>Alert</code>.</p><DD><DL>
<DT><B>Parameters:</B><DD><CODE>cmd</CODE> - the command to be added<DT><B>Throws:</B><DD><CODE><A HREF="../../../java/lang/IllegalStateException.html">IllegalStateException</A></CODE> - if this <code>Item</code> is contained
 within an <code>Alert</code><DD><CODE><A HREF="../../../java/lang/NullPointerException.html">NullPointerException</A></CODE> - if cmd is <code>null</code><DT><B>Since: </B><DD>MIDP 2.0</DD>
</DL>
</DD>
</DL>
<HR>

<A NAME="removeCommand(javax.microedition.lcdui.Command)"><!-- --></A><H3>
removeCommand</H3>
<PRE>
public void <B>removeCommand</B>(<A HREF="../../../javax/microedition/lcdui/Command.html">Command</A>&nbsp;cmd)</PRE>
<DL>
<DD>Removes the context sensitive command from item. If the command is not
 in the <code>Item</code> (tested by comparing the object references),
 the method has
 no effect. If the <code>Item</code> is actually visible on the display, 
 and this  call
 affects the set of visible commands, the implementation should update
 the display as soon as it is feasible to do so.


 If the command to be removed happens to be the default command,
 the command is removed and the default command on this Item is
 set to <code>null</code>.

 The following code:
 <CODE> <pre>
     // Command c is the default command on Item item
     item.removeCommand(c);
 </pre> </CODE>
 is equivalent to the following code:
 <CODE> <pre>
     // Command c is the default command on Item item
     item.setDefaultCommand(null);
     item.removeCommand(c);
 </pre> </CODE><DD><DL>
<DT><B>Parameters:</B><DD><CODE>cmd</CODE> - the command to be removed<DT><B>Since: </B><DD>MIDP 2.0</DD>
</DL>
</DD>
</DL>
<HR>

<A NAME="setItemCommandListener(javax.microedition.lcdui.ItemCommandListener)"><!-- --></A><H3>
setItemCommandListener</H3>
<PRE>
public void <B>setItemCommandListener</B>(<A HREF="../../../javax/microedition/lcdui/ItemCommandListener.html">ItemCommandListener</A>&nbsp;l)</PRE>
<DL>
<DD>Sets a listener for <code>Commands</code> to this <code>Item</code>,
 replacing any previous
 <code>ItemCommandListener</code>. A <code>null</code> reference
 is allowed and has the effect of
 removing any existing listener.

 <p>It is illegal to call this method if this <code>Item</code>
 is contained within an <code>Alert</code>.</p><DD><DL>
<DT><B>Parameters:</B><DD><CODE>l</CODE> - the new listener, or <code>null</code>.<DT><B>Throws:</B><DD><CODE><A HREF="../../../java/lang/IllegalStateException.html">IllegalStateException</A></CODE> - if this <code>Item</code> is contained
 within an <code>Alert</code><DT><B>Since: </B><DD>MIDP 2.0</DD>
</DL>
</DD>
</DL>
<HR>

<A NAME="getPreferredWidth()"><!-- --></A><H3>
getPreferredWidth</H3>
<PRE>
public int <B>getPreferredWidth</B>()</PRE>
<DL>
<DD>Gets the preferred width of this <code>Item</code>.  
 If the application has locked
 the width to a specific value, this method returns that value.
 Otherwise, the return value is computed based on the 
 <code>Item's</code> contents,
 possibly with respect to the <code>Item's</code> preferred height 
 if it is locked.
 See <a href="#sizes">Item Sizes</a> for a complete discussion.<DD><DL>
<DT><B>Returns:</B><DD>the preferred width of the Item<DT><B>Since: </B><DD>MIDP 2.0</DD>
<DT><B>See Also: </B><DD><A HREF="../../../javax/microedition/lcdui/Item.html#getPreferredHeight()"><CODE>getPreferredHeight()</CODE></A>, 
<A HREF="../../../javax/microedition/lcdui/Item.html#setPreferredSize(int, int)"><CODE>setPreferredSize(int, int)</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="getPreferredHeight()"><!-- --></A><H3>
getPreferredHeight</H3>
<PRE>
public int <B>getPreferredHeight</B>()</PRE>
<DL>
<DD>Gets the preferred height of this <code>Item</code>.  
 If the application has locked
 the height to a specific value, this method returns that value.
 Otherwise, the return value is computed based on the 
 <code>Item's</code> contents,
 possibly with respect to the <code>Item's</code> preferred 
 width if it is locked.
 See <a href="#sizes">Item Sizes</a> for a complete discussion.<DD><DL>
<DT><B>Returns:</B><DD>the preferred height of the <code>Item</code><DT><B>Since: </B><DD>MIDP 2.0</DD>
<DT><B>See Also: </B><DD><A HREF="../../../javax/microedition/lcdui/Item.html#getPreferredWidth()"><CODE>getPreferredWidth()</CODE></A>, 
<A HREF="../../../javax/microedition/lcdui/Item.html#setPreferredSize(int, int)"><CODE>setPreferredSize(int, int)</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="setPreferredSize(int, int)"><!-- --></A><H3>
setPreferredSize</H3>
<PRE>
public void <B>setPreferredSize</B>(int&nbsp;width,
                             int&nbsp;height)</PRE>
<DL>
<DD>Sets the preferred width and height for this <code>Item</code>.
 Values for width and height less than <code>-1</code> are illegal.
 If the width is between zero and the minimum width, inclusive,
 the minimum width is used instead.
 If the height is between zero and the minimum height, inclusive,
 the minimum height is used instead.

 <p>Supplying a width or height value greater than the minimum width or 
 height <em>locks</em> that dimension to the supplied
 value.  The implementation may silently enforce a maximum dimension for 
 an <code>Item</code> based on factors such as the screen size. 
 Supplying a value of
 <code>-1</code> for the width or height unlocks that dimension.
 See <a href="#sizes">Item Sizes</a> for a complete discussion.</p>
 
 <p>It is illegal to call this method if this <code>Item</code> 
 is contained within  an <code>Alert</code>.</p><DD><DL>
<DT><B>Parameters:</B><DD><CODE>width</CODE> - the value to which the width should be locked, or
 <code>-1</code> to unlock<DD><CODE>height</CODE> - the value to which the height should be locked, or 
 <code>-1</code> to unlock<DT><B>Throws:</B><DD><CODE><A HREF="../../../java/lang/IllegalArgumentException.html">IllegalArgumentException</A></CODE> - if width or height is less than 
 <code>-1</code><DD><CODE><A HREF="../../../java/lang/IllegalStateException.html">IllegalStateException</A></CODE> - if this <code>Item</code> is contained
 within an <code>Alert</code><DT><B>Since: </B><DD>MIDP 2.0</DD>
<DT><B>See Also: </B><DD><A HREF="../../../javax/microedition/lcdui/Item.html#getPreferredHeight()"><CODE>getPreferredHeight()</CODE></A>, 
<A HREF="../../../javax/microedition/lcdui/Item.html#getPreferredWidth()"><CODE>getPreferredWidth()</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="getMinimumWidth()"><!-- --></A><H3>
getMinimumWidth</H3>
<PRE>
public int <B>getMinimumWidth</B>()</PRE>
<DL>
<DD>Gets the minimum width for this <code>Item</code>.  This is a width
 at which the item can function and display its contents,
 though perhaps not optimally.
 See <a href="#sizes">Item Sizes</a> for a complete discussion.<DD><DL>
<DT><B>Returns:</B><DD>the minimum width of the item<DT><B>Since: </B><DD>MIDP 2.0</DD>
</DL>
</DD>
</DL>
<HR>

<A NAME="getMinimumHeight()"><!-- --></A><H3>
getMinimumHeight</H3>
<PRE>
public int <B>getMinimumHeight</B>()</PRE>
<DL>
<DD>Gets the minimum height for this <code>Item</code>.  This is a height
 at which the item can function and display its contents,
 though perhaps not optimally.
 See <a href="#sizes">Item Sizes</a> for a complete discussion.<DD><DL>
<DT><B>Returns:</B><DD>the minimum height of the item<DT><B>Since: </B><DD>MIDP 2.0</DD>
</DL>
</DD>
</DL>
<HR>

<A NAME="setDefaultCommand(javax.microedition.lcdui.Command)"><!-- --></A><H3>
setDefaultCommand</H3>
<PRE>
public void <B>setDefaultCommand</B>(<A HREF="../../../javax/microedition/lcdui/Command.html">Command</A>&nbsp;cmd)</PRE>
<DL>
<DD>Sets default <code>Command</code> for this <code>Item</code>.  
 If the <code>Item</code> previously had a
 default <code>Command</code>, that <code>Command</code> 
 is no longer the default, but it
 remains present on the <code>Item</code>.

 <p>If not <code>null</code>, the <code>Command</code> object
 passed becomes the default <code>Command</code>
 for this <code>Item</code>.  If the <code>Command</code> object
 passed is not currently present
 on this <code>Item</code>, it is added as if <A HREF="../../../javax/microedition/lcdui/Item.html#addCommand(javax.microedition.lcdui.Command)"><CODE>addCommand(javax.microedition.lcdui.Command)</CODE></A>
 had been called
 before it is made the default <code>Command</code>.</p>

 <p>If <code>null</code> is passed, the <code>Item</code> is set to
 have no default <code>Command</code>.
 The previous default <code>Command</code>, if any, remains present
 on the <code>Item</code>.
 </p>

 <p>It is illegal to call this method if this <code>Item</code>
 is contained within  an <code>Alert</code>.</p><DD><DL>
<DT><B>Parameters:</B><DD><CODE>cmd</CODE> - the command to be used as this <code>Item's</code> default
 <code>Command</code>, or <code>null</code> if there is to 
 be no default command<DT><B>Throws:</B><DD><CODE><A HREF="../../../java/lang/IllegalStateException.html">IllegalStateException</A></CODE> - if this <code>Item</code> is contained
 within an <code>Alert</code><DT><B>Since: </B><DD>MIDP 2.0</DD>
</DL>
</DD>
</DL>
<HR>

<A NAME="notifyStateChanged()"><!-- --></A><H3>
notifyStateChanged</H3>
<PRE>
public void <B>notifyStateChanged</B>()</PRE>
<DL>
<DD>Causes this <code>Item's</code> containing <code>Form</code> to notify
 the <code>Item's</code> <A HREF="../../../javax/microedition/lcdui/ItemStateListener.html"><CODE>ItemStateListener</CODE></A>.
 The application calls this method to inform the
 listener on the <code>Item</code> that the <code>Item's</code>
 state has been changed in
 response to an action.  Even though this method simply causes a call
 to another part of the application, this mechanism is useful for
 decoupling the implementation of an <code>Item</code> (in particular, the
 implementation of a <code>CustomItem</code>, though this also applies to
 subclasses of other items) from the consumer of the item.

 <p>If an edit was performed by invoking a separate screen, and the
 editor now wishes to &quot;return&quot; to the form which contained the
 selected <code>Item</code>, the preferred method is
 <code>Display.setCurrent(Item)</code>
 instead of <code>Display.setCurrent(Displayable)</code>,
 because it allows the
 <code>Form</code> to restore focus to the <code>Item</code>
 that initially invoked the editor.</p>

 <p>In order to make sure that the documented behavior of
 <code>ItemStateListener</code> is maintained, it is up to the caller
 (application) to guarantee that this function is
 not called unless:</p>

 <ul>
 <li>the <code>Item's</code> value has actually been changed, and</li>
 <li>the change was the result of a user action (an &quot;edit&quot;)
 and NOT as a result of state change via calls to
 <code>Item's</code> APIs </li>
 </ul>

 <p>The call to <code>ItemStateListener.itemStateChanged</code>
 may be delayed in order to be serialized with the event stream.
 The <code>notifyStateChanged</code> method does not block awaiting
 the completion of the <code>itemStateChanged</code> method.</p><DD><DL>
<DT><B>Throws:</B><DD><CODE><A HREF="../../../java/lang/IllegalStateException.html">IllegalStateException</A></CODE> - if the <code>Item</code> is not owned
 by a <code>Form</code><DT><B>Since: </B><DD>MIDP 2.0</DD>
</DL>
</DD>
</DL>
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