System.exit退出程序

方法源码：

/**

     * Terminates the currently running Java Virtual Machine. The

     * argument serves as a status code; by convention, a nonzero status

     * code indicates abnormal termination.

     * <p>

     * This method calls the <code>exit</code> method in class

     * <code>Runtime</code>. This method never returns normally.

     * <p>

     * The call <code>System.exit(n)</code> is effectively equivalent to

     * the call:

     * <blockquote><pre>

     * Runtime.getRuntime().exit(n)

     * </pre></blockquote>

     *

     * @param      status   exit status.

     * @throws  SecurityException

     *        if a security manager exists and its <code>checkExit</code>

     *        method doesn't allow exit with the specified status.

     * @see        java.lang.Runtime#exit(int)

     */

    public static void exit(int status) {

        Runtime.getRuntime().exit(status);

    }

这个方法将当前运行的Java虚拟结束，非0状态表示非正常退出

说明：

1. System.exit(0)是正常退出程序，会将整个虚拟机里的内容都停掉清空
2. System.exit(1)或者说非0表示非正常退出程序