小编Var*_*ikh的帖子

我试图打开便携式Wifi热点ON,通过参考此链接:
如何设置android wifihotspot的高级设置

这在三星Galaxy S3 Android v4.4.2上运行良好.(没有问题)
但是在具有相同或更低Android版本的其他设备上,应用程序崩溃并重新启动设备.

代码如下:

package com.android.startwifi;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import android.app.Activity;
import android.content.Context;
import android.net.wifi.WifiConfiguration;
import android.net.wifi.WifiManager;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Toast;


public class Main extends Activity {

public WifiManager wifiManager;
public Context context;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Log.i("hi1","hi");
    createWifiAccessPoint();
}
private void createWifiAccessPoint() {
    WifiManager wifiManager = (WifiManager)getBaseContext().getSystemService(Context.WIFI_SERVICE);
    if(wifiManager.isWifiEnabled())
    {
        wifiManager.setWifiEnabled(false);          
    }       
    Method[] wmMethods = wifiManager.getClass().getDeclaredMethods();  
    boolean methodFound=false;
    for(Method method: wmMethods){
        if(method.getName().equals("setWifiApEnabled")){
            methodFound=true;
            WifiConfiguration …

试图创建一个应用程序来下载SD卡上的文件,这是我的代码:

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        new Thread(new Runnable() {
            public void run() {

                                Log.i("step0","it starts here");
                URLConnection urlConnection = null;
                // TODO Auto-generated method stub
                try {
                    //fetching the URL
                    Log.i("step 1.1","getting the url");
                    URL url = new URL("http://people.opera.com/howcome/2005/ala/sample.pdf");
                    Log.i("step 1.2","captured the url");                
                    urlConnection = url.openConnection();
                    Log.i("step 1.3","captured the url");    

                    urlConnection.connect();
                    Log.i("step 1","fetching the URL");

                    //specifying path and file name 
                    File sdcard = Environment.getExternalStorageDirectory();
                    File file = new File(sdcard, "filename.pdf"); …