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在我的应用程序中，我必须加载包含在文件夹中不同文件中的数据。它运作良好，在第一时间，但它会强制关闭第二次我要加载的文件（经过我修改它们）Android - java.lang.NullPointerException第二次加载文件时
01-07 14:55:51.034: W/dalvikvm(3650): threadid=1: thread exiting with uncaught exception (group=0x40018560)
01-07 14:55:51.044: E/AndroidRuntime(3650): FATAL EXCEPTION: main
01-07 14:55:51.044: E/AndroidRuntime(3650): java.lang.NullPointerException
01-07 14:55:51.044: E/AndroidRuntime(3650): at com.hangin.around.Modele.<init>(Modele.java:27)
01-07 14:55:51.044: E/AndroidRuntime(3650): at com.hangin.around.MainActivity$5.onClick(MainActivity.java:386)
01-07 14:55:51.044: E/AndroidRuntime(3650): at android.view.View.performClick(View.java:2506)
01-07 14:55:51.044: E/AndroidRuntime(3650): at android.view.View$PerformClick.run(View.java:9112)
01-07 14:55:51.044: E/AndroidRuntime(3650): at android.os.Handler.handleCallback(Handler.java:587)
01-07 14:55:51.044: E/AndroidRuntime(3650): at android.os.Handler.dispatchMessage(Handler.java:92)
01-07 14:55:51.044: E/AndroidRuntime(3650): at android.os.Looper.loop(Looper.java:130)
01-07 14:55:51.044: E/AndroidRuntime(3650): at android.app.ActivityThread.main(ActivityThread.java:3835)
01-07 14:55:51.044: E/AndroidRuntime(3650): at java.lang.reflect.Method.invokeNative(Native Method)
01-07 14:55:51.044: E/AndroidRuntime(3650): at java.lang.reflect.Method.invoke(Method.java:507)
01-07 14:55:51.044: E/AndroidRuntime(3650): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:864)
01-07 14:55:51.044: E/AndroidRuntime(3650): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:622)
01-07 14:55:51.044: E/AndroidRuntime(3650): at dalvik.system.NativeStart.main(Native Method)
这里就是我加载在MainActivity代码：
...
@Override
protected void onCreate(Bundle savedInstanceState) {
...
startButton.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View v) {
...
// Checking if storage is available
String storageState = Environment.getExternalStorageState();
if (storageState.equals(Environment.MEDIA_MOUNTED)){
// Listing the files contained in the folder
listFiles = listFiles(new File(Environment.getExternalStorageDirectory(), "HanginAround" + File.separator + "modeles"));
// Creating models
if (!(listFiles == null)){
listeModeles = new Modele[NB_MODELES];
for (int i = 0; i < listFiles.length ; i++){
listeModeles[i] = new Modele(listFiles[i]);
} // for
}// if (listFiles != 0)
}// if (MEDIA_MOUNTED)
else {
// If storage is unavailable, then show a popup indicating it's not available
...
}
...
}
});
...
}
public File[] listFiles(File directory) {
// This function return all *.csv files contained in the folder specified in the parameters
// Listing all files in the folder
File[] list = directory.listFiles();
ArrayList<File> arrayListOfFiles = new ArrayList<File>();
if(!(list == null)) {
for (int i = 0; i < list.length; i++)
{
if (list[i].isFile() && ((list[i].getName().endsWith(".csv")) || (list[i].getName().endsWith(".CSV"))))
{
Log.d(TAG, "MainActivity : " + list[i].getName());
arrayListOfFiles.add(list[i]);
NB_MODELES += 1;
} // if (*.csv)
} // for (i < list.length)
} // if (!(list == null))
if (NB_MODELES == 0){
// Showing a popup indicating there's no models in the directory
...
}
else {
File[] listOfFiles = new File[NB_MODELES];
Iterator<File> it = arrayListOfFiles.iterator();
int i = 0;
while (it.hasNext()){
listOfFiles[i] = (File) it.next();
i++;
}
return listOfFiles;
}
return null;
}
这里是我的课MODELE：
package com.hangin.around;
import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStreamReader;
import java.util.LinkedList;
import java.util.Queue;
import java.util.StringTokenizer;
import android.util.Log;
public class Modele {
private String nom;
private Queue<double[]> fifo = new LinkedList<double[]>();
private File file ;
private final static String TAG = "Modele";
public Modele(File parFile)
{
file = parFile;
// Cutting off the extention from the file name
String strLine = file.getName();
StringTokenizer string = new StringTokenizer(strLine, ".");
nom = string.nextToken();
// Reading the file
try{
// Open the file that is the first
// command line parameter
FileInputStream fstream = new FileInputStream(file);
// Get the object of DataInputStream
DataInputStream in = new DataInputStream(fstream);
BufferedReader br = new BufferedReader(new InputStreamReader(in));
strLine = "";
//Read File Line By Line
while ((strLine = br.readLine()) != null) {
// Add each value into a table
StringTokenizer stringTokenizer = new StringTokenizer(strLine, ";");
double values[] = new double[3];
int i=0;
while (stringTokenizer.hasMoreTokens()) {
values[i]= Double.parseDouble(stringTokenizer.nextToken());
i++;
}
// Adding the tab into the Queue
fifo.add(values);
}
// Close the input stream
in.close();
}catch (Exception e){// Catch exception if any
System.err.println("Error: " + e.getMessage());
}
}
// Class's getters and setters
public void setNom(String parNom)
{
nom=parNom;
}
public void setFifo(Queue<double[]> parFifo)
{
fifo=parFifo;
}
public void setFile(File parFile)
{
file=parFile;
}
public String getNom()
{
return nom;
}
public Queue<double[]> getFifo()
{
return fifo;
}
public File getFile()
{
return file;
}
}
我不能看到那里的错误来自于，你能帮助我吗？ 在此先感谢;）
编辑：
在Modele.java 27号线是
String strLine = file.getName();
而且在MainActitivy.java线386
listeModeles[i] = new Modele(listFiles[i]);
哪个是Modele.java中的第27行？ –
哦，我完全忘记了，对不起。 所以线在Modele.java 27是 '字符串strLine中= file.getName（）;' 而在MainActitivy.java线386是 'listeModeles [I] =新MODELE（listFiles [I]）;' –
@BlackEco不知何故，它无法在Modele.java中找到变量'file'的名称。但是我觉得奇怪的是，当你第一次启动它时会起作用，而不是第二次。你不是在第一次启动时以某种方式删除文件吗？这将是我的猜测 – Bigflow