获取基本类型的默认值 [英] Getting default value for primitive types

问题描述

我手头有一个Java基本类型:

I have a Java primitive type at hand:

Class<?> c = int.class; // or long.class, or boolean.class

我想为该类获取一个默认值-具体来说，如果未初始化，则将该值分配给该类型的字段.例如，0表示数字，false表示布尔值.

I'd like to get a default value for this class -- specifically, the value is assigned to fields of this type if they are not initialized. E.g., 0 for a number, false for a boolean.

有通用的方法可以做到这一点吗?我试过了:

Is there a generic way to do this? I tried this:

c.newInstance()

但是我得到的是InstantiationException，而不是默认实例.

But I'm getting an InstantiationException, and not a default instance.

推荐答案

Guava库已经包含以下内容:
http://guava-libraries.googlecode .com/svn/trunk/javadoc/com/google/common/base/Defaults.html

The Guava Libraries already contains that:
http://guava-libraries.googlecode.com/svn/trunk/javadoc/com/google/common/base/Defaults.html

调用defaultValue将返回任何原始类型(由JLS指定)的默认值，而返回任何其他类型的默认值.

Calling defaultValue will return the default value for any primitive type (as specified by the JLS), and null for any other type.

像这样使用它:

import com.google.common.base.Defaults;
Defaults.defaultValue(Integer.TYPE); //will return 0

这篇关于获取基本类型的默认值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！