情型1：static final属性，无法修改其值。
package m5.d7;
import java.lang.reflect.Field;
public class FieldTest {
public static void main(String[] args) {
try {
A a = new A();
Field field = a.getClass().getDeclaredField("a");
field.setAccessible(true);
field.set(a, 2);
System.out.println(field.get(a));
} catch (SecurityException e) {
e.printStackTrace();
} catch (NoSuchFieldException e) {
e.printStackTrace();
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
}
}
class A {
private static final int a = 1;
}
运行
java.lang.IllegalAccessException: Can not set static final int field m5.d7.A.a to java.lang.Integer
at sun.reflect.UnsafeFieldAccessorImpl.throwFinalFieldIllegalAccessException(Unknown Source)
at sun.reflect.UnsafeFieldAccessorImpl.throwFinalFieldIllegalAccessException(Unknown Source)
at sun.reflect.UnsafeQualifiedStaticIntegerFieldAccessorImpl.set(Unknown Source)
at java.lang.reflect.Field.set(Unknown Source)
at m5.d7.FieldTest.main(FieldTest.java:16)
情型2：final属性，可以修改其值。
package m5.d7;
import java.lang.reflect.Field;
public class FieldTest {
public static void main(String[] args) {
try {
A a = new A();
Field field = a.getClass().getDeclaredField("a");
field.setAccessible(true);
field.set(a, 2);
System.out.println(field.get(a));
} catch (SecurityException e) {
e.printStackTrace();
} catch (NoSuchFieldException e) {
e.printStackTrace();
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
}
}
class A {
private final int a = 1;
}
运行
2