Ⅰ 怎么知道电脑系统是否安装了java
打开cmd指令窗口输入:java-version
返回信息如下即是已经安装Java:
java version "1.8.0_40"
Java(TM) SE Runtime Environment (build 1.8.0_40-b27)
Java HotSpot(TM) 64-Bit Server VM (build 25.40-b25, mixed mode)