安装cassandra失败，因为存在未满足的依赖项

我试着安装卡桑德拉·阿帕奇。我是在按照程序中的步骤进行的。我已将这两行添加到我的源代码中。列表：

ola@station:~$ cat /etc/apt/sources.list | grep "apache"
deb http://www.apache.org/dist/cassandra/debian 30x main
deb-src http://www.apache.org/dist/cassandra/debian 30x main
ola@station:~$ 

我的java版本看起来也不错：

olas@station:~$ java -version
java version "1.8.0_60"
Java(TM) SE Runtime Environment (build 1.8.0_60-b27)
Java HotSpot(TM) 64-Bit Server VM (build 25.60-b23, mixed mode)
olas@station:~$ 

但是，当我尝试安装它时，会收到以下错误消息：

olas@station:~$ sudo apt-get install cassandra
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 cassandra : Depends: openjdk-8-jre-headless but it is not installable or
                      java8-runtime but it is not installable
             Recommends: ntp but it is not going to be installed or
                         time-daemon
E: Unable to correct problems, you have held broken packages.

如何解决此问题？

您需要从后端安装，运行：

sudo add-apt-repository ppa:openjdk-r/ppa
sudo apt-get update
sudo apt-get install cassandra

apt edit-sources

添加以下行：

deb http://httpredir.debian.org/debian jessie-backports main

更新：

apt-get update && apt-get upgrade
apt-get -f install

安装所需的软件包：

apt-get -t jessie-backports install openjdk-8-jre-headless 
apt-get install ntp

安装

cassandra

apt-get install cassandra

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您是否使用apt get安装了Java？