Java反射3

public class Student {
    public String name;
    public int age;
    public String gender;
    private int money = 300;
    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", gender='" + gender + '\'' +
                ", money=" + money +
                '}';
    }
}
public class ReflectDemo1 {
    public static void main(String[] args) throws ClassNotFoundException, NoSuchFieldException {
       // method1();
        //method2();
        //method3();
        //method4();
    }
    private static void method4() throws ClassNotFoundException, NoSuchFieldException {
        //        Field getDeclaredField(String name)：返回单个成员变量对象
        //1.获取class对象
        Class clazz = Class.forName("com.itheima.myreflect4.Student");
        //2.获取money成员变量
        Field field = clazz.getDeclaredField("money");
        //3.打印一下
        System.out.println(field);
    }
    private static void method3() throws ClassNotFoundException, NoSuchFieldException {
        //        Field getField(String name)：返回单个公共成员变量对象
        //想要获取的成员变量必须是真实存在的
        //且必须是public修饰的.
        //1.获取class对象
        Class clazz = Class.forName("com.itheima.myreflect4.Student");
        //2.获取name这个成员变量
        //Field field = clazz.getField("name");
        //Field field = clazz.getField("name1");
        Field field = clazz.getField("money");
        //3.打印一下
        System.out.println(field);
    }
    private static void method2() throws ClassNotFoundException {
        //        Field[] getDeclaredFields()：返回所有成员变量对象的数组
        //1.获取class对象
        Class clazz = Class.forName("com.itheima.myreflect4.Student");
        //2.获取所有的Field对象
        Field[] fields = clazz.getDeclaredFields();
        //3.遍历
        for (Field field : fields) {
            System.out.println(field);
        }
    }
    private static void method1() throws ClassNotFoundException {
        //        Field[] getFields()：返回所有公共成员变量对象的数组
        //1.获取class对象
        Class clazz = Class.forName("com.itheima.myreflect4.Student");
        //2.获取Field对象.
        Field[] fields = clazz.getFields();
        //3.遍历
        for (Field field : fields) {
            System.out.println(field);
        }
    }
}

// Student类同上一个示例,这里就不在重复提供了
public class ReflectDemo2 {
    public static void main(String[] args) throws ClassNotFoundException, NoSuchFieldException, IllegalAccessException, InstantiationException {
//        Object get(Object obj) 返回由该 Field表示的字段在指定对象上的值。
        //method1();
        //method2();
    }
    private static void method2() throws ClassNotFoundException, NoSuchFieldException, InstantiationException, IllegalAccessException {
        //1.获取class对象
        Class clazz = Class.forName("com.itheima.myreflect4.Student");
        //2.获取成员变量Field的对象
        Field field = clazz.getDeclaredField("money");
        //3.取消一下访问检查
        field.setAccessible(true);
        //4.调用get方法来获取值
        //4.1创建一个对象
        Student student = (Student) clazz.newInstance();
        //4.2获取指定对象的money的值
        Object o = field.get(student);
        //5.打印一下
        System.out.println(o);
    }
    private static void method1() throws ClassNotFoundException, NoSuchFieldException, InstantiationException, IllegalAccessException {
        //        void set(Object obj, Object value)：给obj对象的成员变量赋值为value
        //1.获取class对象
        Class clazz = Class.forName("com.itheima.myreflect4.Student");
        //2.获取name这个Field对象
        Field field = clazz.getField("name");
        //3.利用set方法进行赋值.
        //3.1先创建一个Student对象
        Student student = (Student) clazz.newInstance();
        //3.2有了对象才可以给指定对象进行赋值
        field.set(student,"zhangsan");
        System.out.println(student);
    }
}