Java Process.waitFor() Method Explained

In Java, the Process.waitFor() method is used to wait for the associated child process to terminate and return the exit value of the child process. In other words, it suspends the current thread until the child process is finished.

This method returns an integer value that indicates the exit status of the child process. It returns a value of 0 if the child process terminates normally, and a non-zero value if the child process terminates abnormally.

The Process.waitFor() method is commonly used together with the Process.exitValue() method, which is used to retrieve the exit value of the child process. For example, you can use the waitFor() and exitValue() methods in the following way:

Process process = Runtime.getRuntime().exec("some_command");
int exitValue = process.waitFor();
System.out.println("子进程的退出值为：" + exitValue);

In the code above, Runtime.getRuntime().exec(“some_command”) will create a new process to execute the given command. Then, the waitFor() method will wait for the child process to finish execution and return the exit value. Finally, the exit value will be printed out.

It is important to note that the waitFor() method will cause the current thread to block until the child process is finished. If you do not want the current thread to be blocked, you can create a process using the ProcessBuilder class and start it with the start() method. Then, you can use Process.waitFor() method to wait for the child process to finish. This way, the current thread’s execution will not be blocked.