add demo01

java-demo/pom.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>org.levintech.javademo</groupId>
+    <artifactId>javademo</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+
+</project>
\ No newline at end of file

java-demo/src/main/java/org/levintech/javademo/g3noop/EarnMoney.java

+package org.levintech.javademo.g3noop;
+
+/**
+ * @author levin
+ * Created on 2021/6/17
+ * [雷学委] CSDN/Juejin Code Demo
+ */
+public interface EarnMoney {
+    /**
+     * 赚钱生财之道
+     * @return
+     */
+    String earnW();
+}

java-demo/src/main/java/org/levintech/javademo/g3noop/G3AndOOPDemo.java

+package org.levintech.javademo.g3noop;
+
+/**
+ * @author levin
+ * Created on 2021/6/17
+ * [雷学委] CSDN/Juejin Code Demo
+ */
+public class G3AndOOPDemo {
+    public static void main(String[] args) {
+        System.out.println("【雷学委代码Demo】");
+        EarnMoney wz = new WangZong();
+        EarnMoney wzSon = new XiaoWang01();
+        EarnMoney wzDaughter = new XiaoWang02();
+        System.out.println("王总的生财之道:" + wz.earnW());
+        System.out.println("王总儿子的生财之道:" + wzSon.earnW());
+        System.out.println("王总女儿的生财之道:" + wzDaughter.earnW());
+        System.out.println("------------demo 一下继承 ------------");
+        System.out.println("王总资产：" + ((WangZong) wz).saving());
+        System.out.println("儿子继承的资产：" + ((WangZong) wzSon).saving());
+        System.out.println("女儿继承资产：" + ((WangZong) wzDaughter).saving());
+        System.out.println("------------宣布一下遗嘱 ------------");
+        System.out.println("王总遗嘱：" + ((WangZong) wz).testament());
+    }
+}

java-demo/src/main/java/org/levintech/javademo/g3noop/WangZong.java

+package org.levintech.javademo.g3noop;
+
+/**
+ * @author levin
+ * Created on 2021/6/17
+ * [雷学委] CSDN/Juejin Code Demo
+ */
+public class WangZong implements EarnMoney {
+    /**
+     * 存款
+     * @return
+     */
+    public String saving() {
+        return "¥3000亿";
+    }
+
+    public String earnW() {
+        return "搞房地产挣钱！！！";
+    }
+
+    /**
+     * 遗嘱
+     * @return
+     */
+    public String testament(){
+        return "我有多少"+saving()+"分给儿子1500亿，分给女儿1500亿。";
+    }
+}

java-demo/src/main/java/org/levintech/javademo/g3noop/XiaoWang01.java

+package org.levintech.javademo.g3noop;
+
+/**
+ * @author levin
+ * Created on 2021/6/17
+ * [雷学委] CSDN/Juejin Code Demo
+ */
+public class XiaoWang01 extends WangZong {
+    @Override
+    public String earnW() {
+        return "搞游戏特挣钱！！！";
+    }
+}

java-demo/src/main/java/org/levintech/javademo/g3noop/XiaoWang02.java

+package org.levintech.javademo.g3noop;
+
+/**
+ * @author levin
+ * Created on 2021/6/17
+ * [雷学委] CSDN/Juejin Code Demo
+ */
+public class XiaoWang02 extends WangZong {
+    @Override
+    public String earnW() {
+        return "搞电商生态也特挣钱！！！";
+    }
+}