我试图从用逗号分隔的文件中读取x,y坐标.但是,元素未正确添加到ArrayList.我在哪里错了？
ArrayList<Double> xpointArrayList = new ArrayList<Double>();
ArrayList<Double> ypointArrayList = new ArrayList<Double>();
try {
BufferedReader input = new BufferedReader(new FileReader(args[0]));
String line;
while ((line = input.readLine()) != null) {
line = input.readLine();
String[] splitLine = line.split(",");
double xValue = Double.parseDouble(splitLine[0]);
double yValue = Double.parseDouble(splitLine[1]);
xpointArrayList.add(xValue);
ypointArrayList.add(yValue);
}
input.close();
} catch (IOException e) {
} catch (NullPointerException npe) {
}
double[] xpoints = new double[xpointArrayList.size()];
for (int i = 0; i < xpoints.length; i++) {
xpoints[i] = xpointArrayList.get(i);
}
double[] ypoints = …我已经阅读了文档,但它没有告诉我们如何在open()函数中输入文件路径.
如果文件路径是:
/opt/myapp/report/sample.txt
要么
$MYPATH/report/sample.txt (其中$ MYPATH =/opt/myapp)
以这种方式编写语句是否可以:
f = open('/opt/myapp/report/sample.txt', "r")
要么
f = open('$MYPATH/report/sample.txt', "r")
我试图将对象保存到下面的类的文件,但它给了我java.io.NotSerializableException.
import java.io.FileOutputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;
import java.util.Calendar;
class Saver {
Calendar cal = Calendar.getInstance();
public void save(ArrayList<Product> products) {
for (int i = 0; i < products.size(); i++) {
try {
FileOutputStream saveFile = new FileOutputStream(
"/" + products.get(i) + ".product"
);
ObjectOutputStream oos = new ObjectOutputStream(saveFile);
oos.writeObject(products.get(i));
} catch(Exception ex) {
System.out.println(ex);
}
}
}
}
而产品类看起来像这样:
class Product {
private String title;
private int id;
private double price;
public Product(String title, int id, double price) { …我在磁盘上有一个数据集，正在逐行读取，我想将数据列之一转换为浮点向量（范围为0-23.99999）（当天）。
数据如下所示：
2010/01/01,00:00:00.979131, 27.4485, 51.9362, 14.8, 6
2010/01/01,00:00:01.021977, 27.5149, 51.9375, 16.0, 6
2010/01/01,00:00:01.074032, 27.4797, 51.9446, 14.5, 10
2010/01/01,00:00:01.663689, 25.8441,-152.8141, 14.6, 6
2010/01/01,00:00:01.639541, 25.8744,-152.6122, 1.5, 5
2010/01/01,00:00:02.232099, -2.2447, 11.5023, 18.8, 6
2010/01/01,00:00:02.256351, -0.8135, 27.3139, 17.7, 5
2010/01/01,00:00:02.306734, -2.7797, 28.5109, 26.0, 5
2010/01/01,00:00:02.620765, 25.6656,-154.2029, 26.2, 9
2010/01/01,00:00:02.658495, 25.6698,-154.2157, 23.0, 6
2010/01/01,00:00:02.731266, -5.7106, 126.4517, 3.6, 5
2010/01/01,00:00:02.787495, -5.7138, 126.5210, 24.4, 8
2010/01/01,00:00:02.811636, -3.2453, 124.6919, 21.1, 8
第2栏（例如00：00：00.979131）很有趣，我想做类似的事情
setenv GNUTERM 'x11';
fid = fopen('myfile.txt', 'r');
m = textscan(fid, '%d%d%d%d/%d%d/%d%d, %d%d:%d%d:%d%f, %f, %f, %f, %d'); …我的android File.exists功能有一个奇怪的问题.以下是我的代码
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
super.onCreateView(inflater, container, savedInstanceState);
View view = inflater.inflate(R.layout.fragment_file_browser, container);
DataBaseHelper tmpHelper = new DataBaseHelper(getActivity());
ButtonInfoContainer infoContainer = tmpHelper.getVideoWithId(videoId);
//Tmp way to use this. When UX is finished will create a better way.
File f = new File(Environment.getExternalStorageDirectory() + "/aslkfj");
Log.i(StaticValues.TAG, Environment.getExternalStorageDirectory() + "/aslkfj");
LinearLayout tmpView2 = (LinearLayout) view.findViewById(R.id.custom_recordings);
if(f.exists());
{
Log.i(StaticValues.TAG, "f exists");
String[] tmp = f.list();
View tmpView = null;
if(tmp != null)
{
for(int i = 0; …我在两个不同的班级有两个arraylists.一种是存储交易对象temporarily和其他permanent.我使用一种addAll方法将对象从temporaryarraylist 复制到permanent.然后将对象从permanentarraylist 保存到file.当我的程序重新启动时,permanentarraylists中的对象将从中恢复file.但我得到一个例外.我的代码有什么问题？
import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.util.ArrayList;
/****@author Haleemdeen*/public class FileImportExport {
Run Code Online (Sandbox Code Playgroud)private ArrayList<Stock> permntTransactions=new ArrayList<Stock>(); void cancatToPerrmntTransactions(ArrayList<Stock> arraylist1){ permntTransactions.addAll(arraylist1); } ArrayList<Stock> displayPermntTransactions(){ return permntTransactions; } void exportToFile(){ try{ // Catch errors in I/O if necessary. // Open a file to write to, named SavedObj.sav. FileOutputStream saveFile=new FileOutputStream("SaveObj.sav"); // Create an ObjectOutputStream to put …
我想从文件中读取并写入文件.输入文件如下
<ORLANDO> <0%>
As I remember, Adam, it was upon this fashion bequeathed me by will but poor a thousand crowns, and, as thou sayest,
<ORLANDO>
"A s I r e m e m b e r A d a m i t w a s u p o n t h i s f a s h i o n b e q u e a t h e d m e b y w i l l b …我已经看到一个较旧的问题,答案是下面的代码,但如果我使用netbeans,我已经设计了我的comboBox.所以我认为(我想象的是Java和netbeans中的新东西!)代码的最后一行应该改变,我在哪里插入这段代码？
BufferedReader input = new BufferedReader(new FileReader(filePath));
List<String> strings = new ArrayList<String>();
try {
String line = null;
while (( line = input.readLine()) != null){
strings.add(line);
}
}
catch (FileNotFoundException e) {
System.err.println("Error, file " + filePath + " didn't exist.");
}
finally {
input.close();
}
String[] lineArray = strings.toArray(new String[]{});
JComboBox comboBox = new JComboBox(lineArray);
以下代码给了我一个段错误,我不知道为什么.除了最后返回0之外,它是我的主函数中唯一的代码.此外,它成功打印"fr open".
//create file pointer and open file
FILE *fr;
fr = fopen("IntegerArray.txt", "r");
if(fr = NULL){
printf("fr is null\n");
}
else{
printf("fr opened\n");
}
int ch = fgetc(fr);
ch = fgetc(fr);
我的Java隐藏文件有问题.我想写一个隐藏的txt文件,但它总是说"访问被拒绝".我的建议是让文件可见,写入文件然后再次隐藏.但是如何让隐藏文件可见？