小编nkv*_*nkv的帖子

为什么System.out.println(e.getCause());给出null？并且可以像这样存储整个HashSet集合吗？

private void saving() throws IOException, ClassNotFoundException {
    ObjectOutputStream out = null;
    try {
        out = new ObjectOutputStream(new BufferedOutputStream(new FileOutputStream(dataFile)));

        out.writeObject(c);

    } catch (java.io.NotSerializableException e) {
        System.out.println(e.getCause());
    } finally {
        out.close();
    }
}

用来printStackTrace()代替getCause()

java.io.NotSerializableException: Data$1
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1180)
    at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1528)
    at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1493)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1416)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1174)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:346)
    at java.util.HashSet.writeObject(HashSet.java:284)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:616)
    at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:962)
    at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1480)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1416)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1174)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:346)
    at Prozor.saving(Prozor.java:81)
    at Prozor.actionPerformed(Prozor.java:57) …

我会很简短,我拥有的是什么

array=( one.a two.b tree.c four.b five_b_abc)

我要这个

array=( two.b four.b five_b_abc )

从这里 我发现了这个

# replace any array item matching "b*" with "foo"
array=( foo bar baz )
array=( "${array[@]/%b*/foo}" )
echo "${orig[@]}"$'\n'"${array[@]}"

怎么这不起作用

array2=( ${array[@]//%^.p/})

结果 array2=array

这会删除所有p

array2=(${array[@]/*p*/})

结果 array2=( one.a tree.c )

我需要一个想法如何添加^ p(所有接受p),并得到我的解决方案

array2=(${array[@]/*^p*/}

它是一个相当大的数组,大约10k元素,我需要这样做,我需要它尽可能快地与数据,所以请不要循环解决方案.

它关于 http://en.wikipedia.org/wiki/Parallel_(software)和非常丰富的联机帮助页http://www.gnu.org/software/parallel/man.html

(for x in `cat list` ; do 
       do_something $x
   done) | process_output

被这取代

 cat list | parallel do_something | process_output

我正试图在此实现这一点

    while [ "$n" -gt 0 ]
        do          
        percentage=${"scale=2;(100-(($n / $end) * 100))"|bc -l}}
    #get url from line specified by n from file done1              
nextUrls=`sed -n "${n}p" < done1`
    echo -ne "${percentage}%  $n / $end urls saved going to line 1. current: $nextUrls\r"
#    function that gets links from the url
    getlinks $nextUrls
#save n
    echo …

当您通过终端安装或更新时,有些人可能已经发现在Ubuntu中

你得到一个类似的问题

"你有没有安装或删除包[Y/n]？"

当你按下输入时就像输入"Y"或"y"时一样

所以我想知道如何在bash中实现这一点这是我到目前为止所拥有的？

echo "question?[Y/n]"
read choose
if [ $choose ~= "Y" ] [ $choose ~= "y" ] [ $choose ~= "" ]
then 
#code
fi

当hinernate尝试将此类映射到MySQL数据库时

/*
*To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package projekat.entities;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import java.util.Objects;
import javax.persistence.*;
import org.apache.tapestry5.beaneditor.NonVisual;

/**
 *
 * @author nikola
 */
@Entity
public class Student implements Serializable {

  @Id
  @NonVisual
  @GeneratedValue(strategy = GenerationType.AUTO)
  @Basic(optional = false)
  private Long kljuc;
  @Basic(optional = false)
  private String ime;
  @Basic(optional = false)
  private String prezime;
  @Basic(optional = false)
  private Integer index;
  @ManyToMany
  private List<Grupa> grupaList = …