getsetprop.html

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<TITLE>Getting and Setting a Property of a Bean
(Java Developers Almanac Example)
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  <h3>
    e6.  
    Getting and Setting a Property of a Bean</h3>

This example demonstrates how to get and set the value of a property
in a bean using <code>Expression</code> and <code>Statement</code>.  The example gets
and sets three types of properties, an <code>Object</code>, a primitive type,
and an array.  Both these classes use the name of the method that gets
or sets the property.
 

<pre>
    Object o = new MyBean();
    try {
        // Get the value of prop1
        Expression expr = new Expression(o, <font color="#0066ff"><i>"getProp1"</i></font>, new Object[0]);
        expr.execute();
        String s = (String)expr.getValue();
    
        // Set the value of prop1
        Statement stmt = new Statement(o, <font color="#0066ff"><i>"setProp1"</i></font>, new Object[]{<font color="#0066ff"><i>"new string"</i></font>});
        stmt.execute();
    
        // Get the value of prop2
        expr = new Expression(o, <font color="#0066ff"><i>"getProp2"</i></font>, new Object[0]);
        expr.execute();
        int i = ((Integer)expr.getValue()).intValue();
    
        // Set the value of prop2
        stmt = new Statement(o, <font color="#0066ff"><i>"setProp2"</i></font>, new Object[]{<font color="#0066ff"><i>new Integer(123)</i></font>});
        stmt.execute();
    
        // Get the value of prop1
        expr = new Expression(o, <font color="#0066ff"><i>"getProp3"</i></font>, new Object[0]);
        expr.execute();
        byte[] bytes = (byte[])expr.getValue();
    
        // Set the value of prop1
        stmt = new Statement(o, <font color="#0066ff"><i>"setProp3"</i></font>, new Object[]{<font color="#0066ff"><i>new byte[]{0x12, 0x23}</i></font>});
        stmt.execute();
    } catch (Exception e) {
    }
    
    public class <font color="#0066ff"><i>MyBean</i></font> {
        // Property prop1
        String prop1;
        public String getProp1() {
            return prop1;
        }
        public void setProp1(String s) {
            prop1 = s;
        }
    
        // Property prop2
        int prop2;
        public int getProp2() {
            return prop2;
        }
        public void setProp2(int i) {
            prop2 = i;
        }
    
        // Property prop3
        byte[] prop3;
        public byte[] getProp3() {
            return prop3;
        }
        public void setProp3(byte[] bytes) {
            prop3 = bytes;
        }
    }
</pre>
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            &nbsp;Related Examples
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e1. <a class="eglink" href="BasicBean.html?l=rel">
    The Quintessential Bean
</a>
<br>

e2. <a class="eglink" href="Bound.html?l=rel">
    Implementing a Bound Property
</a>
<br>

e3. <a class="eglink" href="Constrain.html?l=rel">
    Implementing a Constrained Property
</a>
<br>

e4. <a class="eglink" href="NewBean.html?l=rel">
    Instantiating a Bean
</a>
<br>

e5. <a class="eglink" href="GetProps.html?l=rel">
    Listing the Property Names of a Bean
</a>
<br>


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        See also: 
<a class="eglink" href="/egs/java.beans/pkg.html?l=rel#Events">
    Events
</a>&nbsp;&nbsp;

<a class="eglink" href="/egs/java.beans/pkg.html?l=rel#Serialization">
    Serialization
</a>&nbsp;&nbsp;

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