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我是Android新手。我目前正在開發一個多選文件列表和壓縮文件。所以我編碼多選擇，但我有異常，這是IllegalstateException。到目前爲止，我已經在我的onSdcardistner方法執行調試工作，但listTree（）方法不起作用。當我從OnsdcardlistenerMethod（） 稱之爲所以這裏是代碼和異常IllegalStateException發生在調用方法
package com.example.testmutilplefile;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import java.io.File;
import java.io.FileFilter;
import java.util.ArrayList;
import android.os.Environment;
import android.util.Log;
import android.app.Activity;
import android.view.View;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.ArrayAdapter;
public class MainActivity extends ActionBarActivity {
public static String TAG = "SelectFiles";
// public static String ZIP="zippingfile";
public File filepath = Environment.getExternalStorageDirectory();
public ListView directorytree;
public ListView filetree;
public TextView directorynames;
public TextView files;
public Button sdclick;
public ArrayList<File> directorylist = new ArrayList<File>();
public ArrayList<String> directoryname = new ArrayList<String>();
public ArrayList<File> filelist = new ArrayList<File>();
public ArrayList<String> myfilename = new ArrayList<String>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initialComponent();
sdclick.setClickable(true);
}
public void initialComponent() {
sdclick = (Button) findViewById(R.id.sdcardbutton);
directorynames = (TextView) findViewById(R.id.directoriesname);
files = (TextView) findViewById(R.id.filesname);
directorytree = (ListView) findViewById(R.id.directorySelectionList);
filetree = (ListView) findViewById(R.id.fileSelectionList);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public void onSdCardListener(View v) {
File parentfile = filepath.getParentFile();
Log.d(TAG, parentfile.toString());
//listTree();
if (filepath.equals(Environment.getExternalStorageDirectory())) {
Toast.makeText(this, "cant exit external storage",
Toast.LENGTH_SHORT).show();
listTree();
} else {
filepath = parentfile;
//listTree();
}
}
private void listTree() {
// TODO Auto-generated method stub
FileFilter filefilter = new FileFilter() {
public boolean accept(File file) {
return file.isFile();
}
};
FileFilter directoryfilter = new FileFilter() {
public boolean accept(File file) {
return file.isDirectory();
}
};
/* List of Directory */
if (filepath.exists() && filepath.length() > 0) {
File[] directorylistArray = filepath.listFiles(directoryfilter);
for (File file : directorylistArray) {
directorylist.add(file);
directoryname.add(file.getName());
}
ArrayAdapter<String> directoryadapter = new ArrayAdapter<String>(
this, android.R.layout.simple_list_item_1, directoryname);
directorytree.setAdapter(directoryadapter);
File[] filelistArray = filepath.listFiles(filefilter);
for (File file : filelistArray) {
filelist.add(file);
myfilename.add(file.getName());
}
ArrayAdapter<String> fileadapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, myfilename);
filetree.setAdapter(fileadapter);
Log.d(TAG, "List Created");
}
}
}
和我的例外是
01-15 13:06:57.640: D/dalvikvm(804): GC_FOR_ALLOC freed 65K, 5% free 3223K/3364K, paused 25ms, total 28ms
01-15 13:06:57.650: I/dalvikvm-heap(804): Grow heap (frag case) to 4.285MB for 1127536-byte allocation
01-15 13:06:57.690: D/dalvikvm(804): GC_FOR_ALLOC freed 3K, 4% free 4321K/4468K, paused 35ms, total 35ms
01-15 13:06:57.980: D/gralloc_goldfish(804): Emulator without GPU emulation detected.
01-15 13:07:08.210: D/SelectFiles(804): /storage
01-15 13:07:08.340: D/AndroidRuntime(804): Shutting down VM
01-15 13:07:08.340: W/dalvikvm(804): threadid=1: thread exiting with uncaught exception (group=0xb2a77ba8)
01-15 13:07:08.430: E/AndroidRuntime(804): FATAL EXCEPTION: main
01-15 13:07:08.430: E/AndroidRuntime(804): Process: com.example.testmutilplefile, PID: 804
01-15 13:07:08.430: E/AndroidRuntime(804): java.lang.IllegalStateException: Could not execute method of the activity
01-15 13:07:08.430: E/AndroidRuntime(804): at android.view.View$1.onClick(View.java:3823)
01-15 13:07:08.430: E/AndroidRuntime(804): at android.view.View.performClick(View.java:4438)
01-15 13:07:08.430: E/AndroidRuntime(804): at android.view.View$PerformClick.run(View.java:18422)
01-15 13:07:08.430: E/AndroidRuntime(804): at android.os.Handler.handleCallback(Handler.java:733)
01-15 13:07:08.430: E/AndroidRuntime(804): at android.os.Handler.dispatchMessage(Handler.java:95)
01-15 13:07:08.430: E/AndroidRuntime(804): at android.os.Looper.loop(Looper.java:136)
01-15 13:07:08.430: E/AndroidRuntime(804): at android.app.ActivityThread.main(ActivityThread.java:5001)
01-15 13:07:08.430: E/AndroidRuntime(804): at java.lang.reflect.Method.invokeNative(Native Method)
01-15 13:07:08.430: E/AndroidRuntime(804): at java.lang.reflect.Method.invoke(Method.java:515)
01-15 13:07:08.430: E/AndroidRuntime(804): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
01-15 13:07:08.430: E/AndroidRuntime(804): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
01-15 13:07:08.430: E/AndroidRuntime(804): at dalvik.system.NativeStart.main(Native Method)
01-15 13:07:08.430: E/AndroidRuntime(804): Caused by: java.lang.reflect.InvocationTargetException
01-15 13:07:08.430: E/AndroidRuntime(804): at java.lang.reflect.Method.invokeNative(Native Method)
01-15 13:07:08.430: E/AndroidRuntime(804): at java.lang.reflect.Method.invoke(Method.java:515)
01-15 13:07:08.430: E/AndroidRuntime(804): at android.view.View$1.onClick(View.java:3818)
01-15 13:07:08.430: E/AndroidRuntime(804): ... 11 more
01-15 13:07:08.430: E/AndroidRuntime(804): Caused by: java.lang.NullPointerException
01-15 13:07:08.430: E/AndroidRuntime(804): at com.example.testmutilplefile.MainActivity.listTree(MainActivity.java:118)
01-15 13:07:08.430: E/AndroidRuntime(804): at com.example.testmutilplefile.MainActivity.onSdCardListener(MainActivity.java:91)
01-15 13:07:08.430: E/AndroidRuntime(804): ... 14 more
01-15 13:07:18.930: I/Process(804): Sending signal. PID: 804 SIG: 9
請給我一個指導我怎麼能解決這個問題，我沒有得到它在此先感謝
東西是空的檢查你的日誌是否正確引起：java.lang.NullPointerException – Nik