无法通过反射设置布尔值

Question

我无法Boolean使用Java反射将值设置为字段。字段数据类型为java.lang.Boolean。但是，如果数据类型是基本类型，即I，我就可以设置该值boolean。

这是带有Boolean类型和原始类型的简单VO ：

public class TestVO {
    private Boolean bigBoolean;
    private boolean smallBoolean;
}

这是我的java反射代码：

public class TestClass {
    public static void main(String args[])
            throws IllegalArgumentException, IllegalAccessException, NoSuchFieldException, SecurityException {
        TestVO testVO1 = new TestVO();

        Class testVO = testVO1.getClass();
        Field smallBooleanField = TestVO.class.getDeclaredField("smallBoolean");
        Field bigBooleanField = TestVO.class.getDeclaredField("bigBoolean");

        String name1 = smallBooleanField.getName();
        System.out.println("SmallBoolean Fieldname is: " + name1);

        smallBooleanField.setAccessible(true);

        // get the value of this private field
        Boolean fieldValue = (Boolean) smallBooleanField.get(testVO1);
        System.out.println("fieldValue = " + fieldValue);

        smallBooleanField.setAccessible(true);
        smallBooleanField.setBoolean(testVO1, true);

        // get the value of this private field
        fieldValue = (Boolean) smallBooleanField.get(testVO1);
        System.out.println("fieldValue = " + fieldValue);

        name1 = bigBooleanField.getName();
        System.out.println("bigBooleanField Fieldname is: " + name1);

        bigBooleanField.setAccessible(true);

        // get the value of this private field
        fieldValue = (Boolean) bigBooleanField.get(testVO1);
        System.out.println("fieldValue = " + fieldValue);

        bigBooleanField.setAccessible(true);
        bigBooleanField.setBoolean(testVO1, new Boolean(true));

        // get the value of this private field
        fieldValue = (Boolean) bigBooleanField.get(testVO1);
        System.out.println("fieldValue = " + fieldValue);

    }
}

输出为：

SmallBoolean Fieldname is: smallBoolean
fieldValue = false
fieldValue = true
bigBooleanField Fieldname is: bigBoolean
fieldValue = null
Exception in thread "main" java.lang.IllegalArgumentException: Can not set java.lang.Boolean field TestVO.bigBoolean to (boolean)true
    at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:167)
    at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:175)
    at sun.reflect.UnsafeObjectFieldAccessorImpl.setBoolean(UnsafeObjectFieldAccessorImpl.java:90)
    at java.lang.reflect.Field.setBoolean(Field.java:795)
    at TestClass.main(TestClass.java:44)

我试图设定bigBoolean与价值new Boolean(true)，Boolean.TRUE，true等什么作品。

Answer 1

根据此，bigBoolean.setBoolean()被调用以设置一个字段，该字段是用原语类型的值的参考布尔类型。在非反射等效项中Boolean val = true，编译器会将原始类型’true’转换（或装箱）为引用类型，new Boolean(True)以便其类型检查将接受该语句。

使用反射时，类型检查仅在运行时发生，因此没有机会将值装箱。IllegalArgumentException由于不可转换类型，这会强制抛出