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<a href="http://www.bruceeckel.com/javabook.html">Bruce Eckel's Thinking in Java</a>
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<H2 ALIGN=LEFT>
Labels</H2>
<DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">A
<A NAME="Index1617"></A><A NAME="Index1618"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Label</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
does exactly what it sounds like it should: places a label on the form. This is
particularly important for text fields and text areas that don&#8217;t have
labels of their own, and can also be useful if you simply want to place textual
information on a form. You can, as shown in the first example in this chapter,
use 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>drawString(&#160;)</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
inside 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>paint(&#160;)</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
to place text in an exact location. When you use a 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Label</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
it allows you to (approximately) associate the text with some other component
via the layout manager (which will be discussed later in this chapter).
</FONT><P></DIV><DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">With
the constructor you can create a blank label, a label with initial text in it
(which is what you&#8217;ll typically do), and a label with an alignment of 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>CENTER</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>LEFT</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
or 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>RIGHT</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
(
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>static
final int
</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">s
defined in class 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>Label</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">).
You can also change the label and its alignment with <A NAME="Index1619"></A><A NAME="Index1620"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>setText(&#160;)</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
and <A NAME="Index1621"></A><A NAME="Index1622"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>setAlignment(&#160;)</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
and if you&#8217;ve forgotten what you&#8217;ve set these to you can read the
values with <A NAME="Index1623"></A><A NAME="Index1624"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>getText(&#160;)</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
and <A NAME="Index1625"></A><A NAME="Index1626"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>getAlignment(&#160;)</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">.
This example shows what you can do with labels:
</FONT><P></DIV>

<font color="#990000"><PRE><font color="#009900">//: Label1.java</font>
<font color="#009900">// Using labels</font>
<font color="#0000ff">import</font> java.awt.*;
<font color="#0000ff">import</font> java.applet.*;

<font color="#0000ff">public</font> <font color="#0000ff">class</font> Label1 <font color="#0000ff">extends</font> Applet {
  TextField t1 = <font color="#0000ff">new</font> TextField("t1", 10);
  Label labl1 = <font color="#0000ff">new</font> Label("TextField t1");
  Label labl2 = <font color="#0000ff">new</font> Label("                   ");
  Label labl3 = <font color="#0000ff">new</font> Label("                    ",
    Label.RIGHT);
  Button b1 = <font color="#0000ff">new</font> Button("Test 1");
  Button b2 = <font color="#0000ff">new</font> Button("Test 2");
  <font color="#0000ff">public</font> <font color="#0000ff">void</font> init() {
    add(labl1); add(t1);
    add(b1); add(labl2);
    add(b2); add(labl3);
  }
  <font color="#0000ff">public</font> <font color="#0000ff">boolean</font> action (Event evt, Object arg) {
    <font color="#0000ff">if</font>(evt.target.equals(b1))
      labl2.setText("Text set into Label");
    <font color="#0000ff">else</font> <font color="#0000ff">if</font>(evt.target.equals(b2)) {
      <font color="#0000ff">if</font>(labl3.getText().trim().length() == 0)
        labl3.setText("labl3");
      <font color="#0000ff">if</font>(labl3.getAlignment() == Label.LEFT)
        labl3.setAlignment(Label.CENTER);
      <font color="#0000ff">else</font> <font color="#0000ff">if</font>(labl3.getAlignment()==Label.CENTER)
        labl3.setAlignment(Label.RIGHT);
      <font color="#0000ff">else</font> <font color="#0000ff">if</font>(labl3.getAlignment() == Label.RIGHT)
        labl3.setAlignment(Label.LEFT);
    }
    <font color="#0000ff">else</font> 
      <font color="#0000ff">return</font> <font color="#0000ff">super</font>.action(evt, arg);
    <font color="#0000ff">return</font> <font color="#0000ff">true</font>;
  }
} <font color="#009900">///:~ </PRE></font></font><DIV ALIGN=LEFT><P></DIV><DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">The
first use of the label is the most typical: labeling a 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>TextField</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
or 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>TextArea</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">.
In the second part of the example, a bunch of empty spaces are reserved and
when you press the &#8220;Test 1&#8221; button 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>setText(&#160;)</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
is used to insert text into the field. Because a number of blank spaces do not
equal the same number of characters (in a <A NAME="Index1627"></A><A NAME="Index1628"></A><A NAME="Index1629"></A>proportionally-spaced
font) you&#8217;ll see that the text gets truncated when inserted into the label.
</FONT><P></DIV><DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">The
third part of the example reserves empty space, then the first time you press
the &#8220;Test 2&#8221; button it sees that there are no characters in the
label (since <A NAME="Index1630"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>trim(&#160;)</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
removes all of the blank spaces at each end of a 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>String</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">)
and inserts a short label, which is initially left-aligned. The rest of the
times you press the button it changes the alignment so you can see the effect.
</FONT><P></DIV><DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">You
might think that you could create an empty label and then later put text in it
with 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>setText(&#160;)</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">.
However, you cannot put text into an empty label &#8211; presumably because it
has zero width &#8211; so creating a label with no text seems to be a useless
thing to do. In the example above, the &#8220;blank&#8221; label is filled with
empty spaces so it has enough width to hold text that&#8217;s placed inside
later.
</FONT><P></DIV><DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">Similarly,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>setAlignment(&#160;)
</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">has
no effect on a label that you&#8217;d typically create with text in the
constructor. The label width is the width of the text, so changing the
alignment doesn&#8217;t do anything. However, if you start with a long label
and then change it to a shorter one you can see the effect of the alignment.
</FONT><P></DIV><DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">These
behaviors occur because of the default <A NAME="Index1631"></A><A NAME="Index1632"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><I>layout
manager
</I></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
that&#8217;s used for applets, which causes things to be squished together to
their smallest size. Layout managers will be covered later in this chapter,
when you&#8217;ll see that other layouts don&#8217;t have the same effect.
</FONT><a name="_Toc375545452"></a><a name="_Toc408018688"></a><P></DIV>

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