小编Lav*_*nia的帖子

我想从criteria.txt文件中读取 ,以标记化并在同一文件的末尾附加标记.该程序抛出异常:No file found!我不知道我的错误在哪里.任何建议都会对我有所帮助.先感谢您!

这是我的代码:

import java.io.*;
import java.util.StringTokenizer;

public class Test
{
    private FileReader fr;
    private BufferedReader br;
    private FileWriter fw;
    private BufferedWriter bw;
    private StringTokenizer strtok;
    private String s;

    //constructor
    public Test()  
    {
        try
        {
            fw=new FileWriter("criteria.txt", true);
            bw=new BufferedWriter(fw);

            try
            {
                fr=new FileReader("criteria.txt");
                br=new BufferedReader(fr);

                while((s=br.readLine())!=null)
                {
                    strtok=new StringTokenizer(s," ");
                    while(strtok.hasMoreTokens())
                    {
                        bw.write("\n"+strtok.nextToken());
                    }
                    br.close();
                }
            }
            catch(FileNotFoundException e)
            {
                System.out.println("File was not found!");
            }
            catch(IOException e)    
            {
                System.out.println("No file found!");
            }

            bw.close(); …

我有一个矢量:

p[0]=0.40816269
p[1]=0.37576407
p[2]=0.16324950
p[3]=0.05282373

我需要以4位小数的形式打印矢量值作为百分比.我试过了:

for(int i=0; i<p.length;i++)
{
    System.out.printf("Criterion "+i+" has the weigth=%.4f \n" , p[i]*100);
}

这给了我:

Criterion 0 has the weigth=40.8163, .....

但我想打印:

Criterion 0 has the weigth=40.8163 %, ..... 

我不能在每行的末尾添加符号"%".如果我尝试:

System.out.printf("Criterion "+i+" has the weigth=%.4f %\n" , p[i]*100);

要么:

System.out.printf("Criterion "+i+" has the weigth=%.4f "+"%\n" , p[i]*100);

程序引发异常.先感谢您!

我试图生成随机基本的数学运算(加法,减法,乘法和除法),有时我的函数返回NaN.我使用了函数parseInt(),但我仍然遇到同样的问题.如果有人可以帮我提出任何建议,我将不胜感激.先感谢您!

Here is my code:

function randNum(min,max)
{
    var num = min+Math.floor((Math.random()*(max-min+1)));
    return num;
}

var choose, operator, firstNum, secondNum,rightAnswer;
function getProb()
{
    var chooseOp=randNum(1,4);
    choose=parseInt(chooseOp);

if (choose==1)
{
    oprator="+";
    var choose1=randNum(0,10);
    var choose2=randNum(0,10);
    firstNum=parseInt(choose1);
    secondNum=parseInt(choose2);
    document.getElementById("mathProb").innerHTML=firstNum+operator+secondNum+"=";
    rightAnswer=choose1 + choose2;
}
else if (choose==2)
{
    operator="-";
    var choose1=randNum(0,10);
    var choose2=randNum(0,10);
    firstNum=parseInt(choose1);
    secondNum=parseInt(choose2);
    document.getElementById("mathProb").innerHTML=firstNum+operator+secondNum+"=";
    rightAnswer=firstNum - secondNum;
}
else if (choose==3)
{
    operator="x";
    var choose1=randNum(0,10);
    var choose2=randNum(0,10);
    firstNum=parseInt(choose1);
    secondNum=parseInt(choose2);
    document.getElementById("mathProb").innerHTML=firstNum+operator+secondNum+"=";
    rightAnswer=choose1 * choose2;
}
    else if (choose==4)
{
    operator="/";
    var choose1=randNum(0,10); …

我想在表格中间插入一个新行.我正在使用MySql.我怎样才能做到这一点？

我的表中有以下记录:

ZipCode  CityName 

60101,   Addison
60004,   Arlington Heights
60502,   Aurora
62223,   Belleville 
61008,   Belvidere
60105,   Bensenville
60402,   Berwyn
60108,   Bloomingdal
61701,   Bloomington

我想插入一个新记录,但不是在表的末尾.

例如,我想插入:

60103, Bartlett

在第三条记录之后,决赛桌应如下:

60101,   Addison
60004,   Arlington Heights
60502,   Aurora
60103,   Bartlett
62223,   Belleville 
61008,   Belvidere
60105,   Bensenville
60402,   Berwyn
60108,   Bloomingdal
61701,   Bloomington.

任何建议都会对我有所帮助.先感谢您!