alias不能接受参数，请定义如下函数:

An alias is not made to accept parameters, define a function like this:

jcar() { javac $1.java && java $1 ; }

然后使用它:

jcar Program

(jcar旨在作为java-compile-and-run的首字母缩写)

(jcar was intended as an acronym for java-compile-and-run)