Java Reference
In-Depth Information
if you are familiar with the java.util.Map interface, it is easy to understand Bindings .
the Bindings interface inherits from the Map<String,Object> interface. therefore, a Bindings
is simply a Map with a restriction that its keys must be nonempty, non-null strings.
Tip
Listing 3-1 shows how to use a Bindings . It creates an instance of SimpleBindings ,
adds some key-value pairs to it, retrieves the values of the keys, removes a key-value pair,
etc. The get() method of the Bindings interface returns null if the key does not exist or
the key exists and its value is null . If you want to test if a key exists, you need to use its
contains() method.
Listing 3-1. Using Bindings Objects
// BindingsTest.java
package com.jdojo.script;
import javax.script.Bindings;
import javax.script.SimpleBindings;
public class BindingsTest {
public static void main(String[] args) {
// Create a Bindings instance
Bindings params = new SimpleBindings();
// Add some key-value pairs
params.put("msg", "Hello");
params.put("year", 1969);
// Get values
Object msg = params.get("msg");
Object year = params.get("year");
System.out.println("msg = " + msg);
System.out.println("year = " + year);
// Remove year from Bindings
params.remove("year");
year = params.get("year");
boolean containsYear = params.containsKey("year");
System.out.println("year = " + year);
System.out.println("params contains year = " + containsYear);
}
}
 
 
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