How to Inject Null And Empty String Values in Spring

This post shows how you can inject null or empty String as a value for any property in Spring framework.

Injecting empty string

If you are trying to inject an empty string as a value for any property then you can just pass “” as a value for that property.

As example

If you have an Employee class with name as field. Then you can use “” for name property.

If passed as a constructor argument -

<bean id="employeeBean" class="org.netjs.exp.Spring_Example.Employee">
<constructor-arg name="name" value="" />        
</bean> 

If passed as property -

<bean id="employeeBean" class="org.netjs.exp.Spring_Example.Employee">
<property name="name" value=""/>      
</bean>

Injecting null

If you need to inject null value for any field then use the special <null/> element for it, don’t use value=”null”because that will pass "null" as a String value.

So don’t do this -

<bean id="employeeBean" class="org.netjs.exp.Spring_Example.Employee">
<constructor-arg name="name" value="null" />   
</bean>

Use <null/> element instead.

<bean id="employeeBean" class="org.netjs.exp.Spring_Example.Employee">
<constructor-arg name="name">
<null/>
</constructor-arg>
</bean>

If passed as setter property -

<bean id="employeeBean" class="org.netjs.exp.Spring_Example.Employee">
<property name="name"><null/></property>
</bean>

That's all for this topic How to Inject Null And Empty String Values in Spring. If you have any doubt or any suggestions to make please drop a comment. Thanks!

Related Topics

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2. Wiring Collections in Spring
3. Run Time Injection Using Spring Expression Language(SpEL)
4. How to Inject Prototype Scoped Bean in Singleton Bean
5. Lazy Initializing Spring Beans

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