Java view the number of cpu cores and jvm memory

/**
 * 我的机器是8核心，16G内存
 */
public class JvmDemo {
    
    

    public static void main(String[] args) {
    
    
        // 查看机器的核数
        System.out.println(Runtime.getRuntime().availableProcessors());
        // 返回java虚拟机试图使用最大的内存量
        long maxMemory = Runtime.getRuntime().maxMemory();
        // 返回java虚拟机中的内存总量
        long totalMemory = Runtime.getRuntime().totalMemory();
        System.out.println("-Xmx:maxMemory = " + maxMemory + " byte\t" + maxMemory / (double) 1024 / 1024 + " MB");
        System.out.println("-Xms:totalMemory = " + totalMemory + " byte\t" + totalMemory / (double) 1024 / 1024 + " MB");
    }
}