Scanner报错java.util.NoSuchElementException

代码：

import java.util.Scanner;
public class Test_Scanner {
    
    
	public static void main(String[] args) {
    
    
		Scanner sc = new Scanner(System.in);
		String input = sc.next();
		sc.close();
		Scanner in = new Scanner(System.in);
		in.next();
	}
}

编译可以通过，但运行输入第一个数据后抛出异常。

问题：

Exception in thread "main" java.util.NoSuchElementException
	at java.util.Scanner.throwFor(Unknown Source)
	at java.util.Scanner.next(Unknown Source)
	at com.tulun.classandobject.Test_Scanner.main(Test_Scanner.java:12)

原因

源码：

  /**
     * Closes this scanner.
     *
     * <p> If this scanner has not yet been closed then if its underlying
     * {@linkplain java.lang.Readable readable} also implements the {@link
     * java.io.Closeable} interface then the readable's <tt>close</tt> method
     * will be invoked.  If this scanner is already closed then invoking this
     * method will have no effect.
     *
     * <p>Attempting to perform search operations after a scanner has
     * been closed will result in an {@link IllegalStateException}.
     *
     */
    public void close() {
    
    
        if (closed)
            return;
        if (source instanceof Closeable) {
    
    
            try {
    
    
                ((Closeable)source).close();
            } catch (IOException ioe) {
    
    
                lastException = ioe;
            }
        }
        sourceClosed = true;
        source = null;
        closed = true;
    }

 这样理解：创建的多个Scanner对象共用的是同一个输入流(System.in)。调用close()方法时，就关闭了System.in这个输入流。因此对于第二次创建的in来说，System.in已经被关闭了，就无法正常创建出对象，从而会产生java.util.NoSuchElementException异常。

解决方案：

 在代码的最后再调用close()来关闭输入流。

参考资料

https://www.cnblogs.com/qingyibusi/p/5812725.html
https://blog.csdn.net/fashion_man/article/details/82973029