Java exec（）函数参数

Question

这有什么区别 -

Process process=Runtime.getRuntime().exec(
  new String[] {"cmd", "/c", command.toString()},
  null, new File("D:/test"));

和 -

Process process=Runtime.getRuntime().exec(
  command.toString(), null, new File("D:/test"));

如果我使用第一个它正在工作，但如果我使用第二个，它会给出以下异常 -

java.io.IOException: Cannot run program "gst" (in directory "D:\test"): CreateProcess error=2, The system cannot find the file specified
    at java.lang.ProcessBuilder.start(ProcessBuilder.java:1041)
    at java.lang.Runtime.exec(Runtime.java:617)
    at java.lang.Runtime.exec(Runtime.java:450)
    at CommandInvoker.main(CommandInvoker.java:38)
Caused by: java.io.IOException: CreateProcess error=2, The system cannot find the file specified
    at java.lang.ProcessImpl.create(Native Method)
    at java.lang.ProcessImpl.<init>(ProcessImpl.java:385)
    at java.lang.ProcessImpl.start(ProcessImpl.java:136)
    at java.lang.ProcessBuilder.start(ProcessBuilder.java:1022)
    ... 3 more