Define a Person class

package com.ReflectDemo;

interface Information{	// Define Information interface
	public static final String NATIONAL = "China" ;	// Define global constants
	public static final String AUTHOR = "Zhang San" ;	// Define global constants
	public void sayChina() ;		// No parameter, no method to return value
	public String sayHello(String name,int age) ;	// Defines a method with two parameters and returns the contents
}

public class Person implements Information{
	private String name ;
	private int age ;
	public Person(){	// Non parametric structure
	}
	public Person(String name){
		this.name = name ;	// Set name property
	}
	public Person(String name,int age){
		this(name) ;
		this.age = age ;
	}
	public void sayChina(){	// Overwriting method
		System.out.println("Author:" + AUTHOR + "，Nationality:" + NATIONAL) ;
	}
	public String sayHello(String name,int age){
		return "Hello, my name is" + name + "，This year:" + age + "Year old!" ;
	}
	public void setName(String name){
		this.name = name ;
	}
	public void setAge(int age){
		this.age = age ;
	}
	public String getName(){
		return this.name ;
	}
	public int getAge(){
		return this.age ;
	}
};

1, Get all interfaces implemented

Use the getInterfaces() method in the Class class, which is defined in the jdk document as follows:

package com.ReflectDemo;
public class GetInterfaceDemo {
    public static void main(String[] args) {
        Class<?> c1 = null;
        try {
            c1 = Class.forName("com.ReflectDemo.Person"); //Instanced object
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        Class<?> c[] = c1.getInterfaces();  //Get all interfaces implemented
        for (Class<?> i : c) {
            System.out.println("Implemented interface name:" + i.getName());  //Output interface name
        }
    }
}

Program running results:

2, Get parent

Use the getSuperclass() method in the Class class, which is defined in the jdk document as follows:

package com.ReflectDemo;

public class GetSuperClassDemo {
    public static void main(String[] args) {
        Class<?> c1 = null;
        try {
            c1 = Class.forName("com.ReflectDemo.Person"); //Instanced object
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        Class<?> c2 = c1.getSuperclass();  //Get parent class
        System.out.println("Parent class name:" + c2.getName());  //Output the name of the parent class. The Person class does not explicitly inherit a class when it is written, so it inherits the Object class by default
    }
}

Program running results:

3, Get all construction methods

Use the getConstructors() method in the Class,

Use the getName() method in the Class to get the method name

Use the getParameterTypes() method in the Constructor class to get all construction methods

Use the getModifiers() method in the Class to get the permission modifier, and the returned integer

Use the toString() method in the Modifier class to restore the integer of the permission Modifier to a string

package com.ReflectDemo;

import java.lang.reflect.Constructor;
import java.lang.reflect.Modifier;

public class GetConstructorDemo {
    public static void main(String[] args) {
        Class<?> c1 = null;
        try {
            c1 = Class.forName("com.ReflectDemo.Person"); //Instanced object
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        Constructor<?> cons[] = c1.getConstructors();  //Get all construction methods
        for (Constructor<?> con : cons) {
            Class<?> params[] = con.getParameterTypes();  //Get parameter types in construction
            System.out.print("Construction method:");
            int mo = con.getModifiers();  //Get permission modifier, get number
            System.out.print(Modifier.toString(mo) + " ");   //Returns the modifier represented by a number to a string
            System.out.print(con.getName());    //Get construction method name

            System.out.print("(");
            for (int i = 0; i < params.length; i++) {
                System.out.print(params[i].getName() + " arg" + (i+1));  //Print parameter type, parameter name is arg
                if(i < params.length - 1){
                    System.out.print(",");  //Comma between parameters
                }
            }
            System.out.println(") { }");
        }
    }
}

Program running results:

4, Get all methods

Use getMethods() method of Class to get all methods

Use the getReturnType() Method of the Method class to get the return type of the Method

Use getExceptionTypes() Method of Method class to get exception information

package com.ReflectDemo;

import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

public class GetMethodDemo {
    public static void main(String[] args) {
        Class<?> c1 = null;
        try {
            c1 = Class.forName("com.ReflectDemo.Person"); //Instanced object
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        Method method[] = c1.getMethods();  //Get all methods
        for (Method m : method) {
            Class<?> r = m.getReturnType();  //Get the return type of the method
            Class<?> p[] = m.getParameterTypes();
            int mo = m.getModifiers();
            System.out.print(Modifier.toString(mo) + " ");
            System.out.print(r.getName() + " ");
            System.out.print(m.getName());
            System.out.print("(");
            for (int i = 0; i < p.length; i++) {
                System.out.print(p[i].getName() + " arg" + (i+1));
                if(i < p.length - 1){
                    System.out.print(",");
                }
            }

            Class<?> ext[] = m.getExceptionTypes();  //Get exception information
            if(ext.length>0){
                System.out.print(") throws ");
            }else{
                System.out.print(") ");
            }
            for (int j = 0; j < ext.length; j++) {
                System.out.print(ext[j].getName());
                if (j < ext.length - 1){
                    System.out.print(",");
                }
            }
            System.out.println();  //Line feed
            System.out.println(); //Line feed
        }

    }
}

Program running results:

From the result of program running, it can be found that the program not only outputs the methods of Person class, but also the inherited methods of Object class

5, Get all attributes

Use the getDeclaredFields() method of Class to get the properties in this Class

Use the getFields() method of the Class to get the public properties in this Class

Use the getType() method of the Field class to get the type of the property

package com.ReflectDemo;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;

public class GetFieldDemo{
	public static void main(String args[]){
		Class<?> c1 = null ;		// Declare Class object
		try{
			c1 = Class.forName("com.ReflectDemo.Person") ;	// Instanced object
		}catch(ClassNotFoundException e){
			e.printStackTrace() ;
		}
		{	// Attributes of this class
			Field f[] = c1.getDeclaredFields() ;	// Get properties in this class
			for(int i=0;i<f.length;i++){
				Class<?> r = f[i].getType() ;	// Get attribute type
				int mo = f[i].getModifiers() ;	// Number to get modifier
				String priv = Modifier.toString(mo) ; // Restore modifier
				System.out.print("This type of attribute:") ;
				System.out.print(priv + " ") ;	
				System.out.print(r.getName() + " ") ;	// Get attribute type
				System.out.print(f[i].getName()) ;	// Output attribute name
				System.out.println(" ;") ;
			}
		}
		{	// Public attribute
			Field f[] = c1.getFields() ;	// Get public properties in this class
			for(int i=0;i<f.length;i++){
				Class<?> r = f[i].getType() ;	// Get attribute type
				int mo = f[i].getModifiers() ;	// Number to get modifier
				String priv = Modifier.toString(mo) ; // Restore modifier
				System.out.print("Public properties:") ;
				System.out.print(priv + " ") ;	
				System.out.print(r.getName() + " ") ;	// Get attribute type
				System.out.print(f[i].getName()) ;	// Output attribute name
				System.out.println(" ;") ;
			}
		}
	}
};

Program running results: