我试图用cmake建立一个项目。这个项目正在使用Java等。问题是在代码处

find_package(Java REQUIRED)

我收到以下错误：

CMake Error at /usr/share/cmake-2.8/Modules/FindPackageHandleStandardArgs.cmake:108
(message):

Could NOT find Java (missing: Java_JAVA_EXECUTABLE Java_JAR_EXECUTABLE
Java_JAVAC_EXECUTABLE Java_JAVAH_EXECUTABLE Java_JAVADOC_EXECUTABLE)

Call Stack (most recent call first):
/usr/share/cmake-2.8/Modules/FindPackageHandleStandardArgs.cmake:315 (_FPHSA_FAILURE_MESSAGE)
/usr/share/cmake-2.8/Modules/FindJava.cmake:195 (find_package_handle_standard_args)
CMakeLists.txt:66 (find_package)

虽然

which java

输出

/usr/bin/java

怎么会？该错误的原因是什么？