What went wrong: ask 'compileDebug' is ambiguous in root project

What went wrong:
Task 'compileDebug' is ambiguous in root project 'traveller-Android'. Candidates are: 'compileDebugAidl', 'compileDebugAndroidTestAidl', 'compileDebugAndroidTestJavaWithJavac', 'compileDebugAndroidTestNdk', 'compileDebugAndroidTes
tRenderscript', 'compileDebugAndroidTestShaders', 'compileDebugAndroidTestSources', 'compileDebugJavaWithJavac', 'compileDebugNdk', 'compileDebugRenderscript', 'compileDebugShaders', 'compileDebugSources', 'compileDebugUnitTestJav
aWithJavac', 'compileDebugUnitTestSources'

看你的错误信息提示Task 'compileDebug' is ambiguous in root project 'traveller-Android'.，大体意思就是compileDebug命令太模糊，参数不明确，后面提供的是候选，你把compileDebug替换成后面的试试，比如
在命令行中进入项目的根目录，运行 gradlew compileDebugJavaWithJavac