import java.lang.reflect.Field;import java.lang.reflect.Method;import java.util.ArrayList; public class Person {    private String name;//私有属性     public String address;     public Person(String name){         this.name=name;     }               private void setAddress(String address){ //私有方法         this.address=address;     }               public static void main(String[] args) {         try{             Person person=new Person("zhangsan");             Class<Person> cls=Person.class;             //获得私有方法             Method method=cls.getDeclaredMethod("setAddress", new Class[]{String.class});             //设置私有方法可以被访问             method.setAccessible(true);             //调用私有方法             method.invoke(person, new Object[]{"BJUT"});             System.out.println(person.address);//输出BJUT                            //访问私有变量             Field field=cls.getDeclaredField("name");             field.setAccessible(true);             field.set(person, "test中国");            System.out.println(field.get(person));//输出zhangsan                                         ArrayList<String> test = new ArrayList<String>(1000);            Class<ArrayList> tcls = ArrayList.class;                          field = tcls.getDeclaredField("size");             field.setAccessible(true);             field.set(test, 100);            System.out.println(field.get(test));                         System.out.println(test.size());                     }catch(Exception ex){             ex.printStackTrace();         }                }         public class Test {        private String name;//私有属性     } }