lazy-initialization | 易学教程

Lazy field initialization with lambdas

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问题 I would like to implement lazy field initialization (or deferred initialization) without an if statement and taking advantage of lambdas. So, I would like to have the same behavior of the following Foo property but without the if : class A<T>{ private T fooField; public T getFoo(){ if( fooField == null ) fooField = expensiveInit(); return fooField; } } Ignore the fact that this solution is not guaranteeing safe use for: 1) multi-threading; 2) null as a valid value of T . So, to express the

Solve Hibernate Lazy-Init issue with hibernate.enable_lazy_load_no_trans

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I have been suffering from infamous hibernate exception org.hibernate.LazyInitializationException: could not initialize proxy - no Session Now the community is cheering over <property name="hibernate.enable_lazy_load_no_trans" value="true"/> saying it solves the problem but USE IT WITH CAUTION . What they mean by use it with caution? What this property actually does? Please give me any insights. Thanks in advance. uaiHebert The problem with this approach is that you can have the N+1 effect. Imagine that you have the following entity: public class Person{ @OneToMany // default to lazy private

How to solve the LazyInitializationException when using JPA and Hibernate

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问题 I am working on a project for a customer who wants to use lazy initialization. They always get \"lazy initialization exception\" when mapping classes with the default lazy loading mode. @JoinTable(name = \"join_profilo_funzionalita\", joinColumns = {@JoinColumn(name = \"profilo_id\", referencedColumnName = \"profilo_id\")}, inverseJoinColumns = {@JoinColumn(name = \"funzionalita_id\", referencedColumnName = \"funzionalita_id\")}) //@ManyToMany(fetch=FetchType.EAGER) - no exceptions if

Solve Hibernate Lazy-Init issue with hibernate.enable_lazy_load_no_trans

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问题 I have been suffering from infamous hibernate exception org.hibernate.LazyInitializationException: could not initialize proxy - no Session Now the community is cheering over <property name=\"hibernate.enable_lazy_load_no_trans\" value=\"true\"/> saying it solves the problem but USE IT WITH CAUTION . What they mean by use it with caution? What this property actually does? Please give me any insights. Thanks in advance. 回答1: The problem with this approach is that you can have the N+1 effect.