參考網址：https://stackoverflow.com/questions/45456210/could-not-find-tools-jar-when-build-gradle-project
執行：
gradlew.bat clean build -x test
出錯信息：
Parallel execution with configuration on demand is an incubating feature. > Task :compileJava FAILED FAILURE: Build failed with an exception. * What went wrong: Execution failed for task ':compileJava'. > Could not find tools.jar. Please check that D:\Java\jre contains a valid JDK installation.
解決：
在根目錄下新建一個gradle.properties，在其中加上一行即可：
org.gradle.java.home=C:/path/to/your/jdk
