Question

如果函数doesWifiExist为false，如果确实每件事情都正常，我就会出现内存错误。有人告诉我，我做错了什么

想法是获取附近的wifi网络列表，并检查列表中是否存在插入的网络。

这是wifi网络扫描代码和检查wifi网络是否存在的功能。

MainActivity：

    private WiFiConnection _wifiConnection = null;
    static final int MY_PERMISSIONS_REQUEST = 1042;
    private static final String PERMISSIONS_TAG = "PERMISSION";
    ...
   @Override
    protected void onStart() {
        super.onStart();
        _wifiConnection = new WiFiConnection(this);
        startScan();
    }

    @Override
    protected void onStop() {
        super.onStop();

        _wifiConnection.stopScan();
        unregisterReceiver(_wifiScanReceiver);
    }

    void startScan() {
        checkPermission(this);

        registerReceiver(_wifiScanReceiver,
                new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
        Thread t = new Thread(_wifiConnection.getWifiScanner());
        t.start();
    }

    private final BroadcastReceiver _wifiScanReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context c, Intent intent) {
            if (intent.getAction().equals(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION)) {
                if (_wifiConnection != null && _wifiConnection.isWifiEnabled()) {
                    _wifiConnection.updateScanData();
                }

            }
        }
    };


    public static boolean checkPermission(Activity activity) {
        boolean permission = true;
        if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            List<String> requiringList = new ArrayList<>();
            permission = activity.checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED;
            Log.d(PERMISSIONS_TAG, "ACCESS_COARSE_LOCATION: " + permission);
            if (!permission) {
                requiringList.add(Manifest.permission.ACCESS_COARSE_LOCATION);
            }

            if (requiringList.size() > 0) {
                String[] stringArray = requiringList.toArray(new String[0]);
                activity.requestPermissions(stringArray, MY_PERMISSIONS_REQUEST);
            }
        }
        return permission;
    }

    private boolean doesWifiExist(String s){
            String[] array = s.split(" ");
            String ssid = array[0];
            boolean flag = false;
            //Check if wifi exists in the area
            for(int i = 0 ; i < _wifiConnection.getListSSIDs().size(); i++){
                if(_wifiConnection.getListSSIDs().get(i).equals(ssid)){
                    flag = true;
                    break;
                }
            }
            return flag;
        }

WiFiConnection类：

public class WiFiConnection
    {
        private static final int SCAN_INTERVAL = 5000;

        final private List<String> _listSSIDs = new ArrayList<>();

        private WifiManager _wifiManager;

        private final WiFiScanner _startScan = new WiFiScanner();
        private List<ScanResult> scanResults;

        WiFiConnection(Activity activity) {
            _wifiManager = (WifiManager) activity.getApplicationContext().getSystemService(Context.WIFI_SERVICE);
        }

        //Puts wifi networks in a list
        public List<String> getListSSIDs() {

            for(int i = 0; i < scanResults.size(); i++)
            {
                _listSSIDs.add(scanResults.get(i).SSID);
            }
            return _listSSIDs;

        }
        WiFiScanner getWifiScanner() { return _startScan; }
        void stopScan() { _startScan.stop(); }

        boolean isWifiEnabled() { return _wifiManager.isWifiEnabled(); }

        //Gets the wifi networks
        void updateScanData() {
            if ((_wifiManager != null && _wifiManager.isWifiEnabled())) {
                scanResults = _wifiManager.getScanResults();
            }
        }

        //Scans at an interval
        private class WiFiScanner implements Runnable
        {
            private boolean _stop = false;
            public void stop() {_stop = true;}
            @Override
            public void run() {
                while (!_stop) {
                    _listSSIDs.clear();
                    _wifiManager.startScan();
                    try {
                        Thread.sleep(SCAN_INTERVAL);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    }

使用wifiExist的代码。

 //Check if wifi exists in the area
 if(doesWifiExist(barcode.displayValue)){
   //Connects to wifi
   WifiConnect(barcode.displayValue);
   //Saves item in db
   insertItem();

   if(networkSecurity.equals("None")){
      networkPass = empty;
   }
   //Adds item to recyclerview
   historyItems.add(0, new HistoryItem(wifiName + " " + networkSSID, wifiPass + " " + networkPass));
   adapter.notifyItemInserted(0);
 } else
       Snackbar.make(findViewById(R.id.main_activity), R.string.snackInvalidQrCode, Snackbar.LENGTH_SHORT).show();

Answer 1

此方法被多次调用，并且每次都在字段_listSSIDS的末尾添加所有scanResults。

   public List<String> getListSSIDs() {
        for(int i = 0; i < scanResults.size(); i++)
        {
            _listSSIDs.add(scanResults.get(i).SSID);
        }
        return _listSSIDs;
    }

使用带有新List的局部变量或更好地设置那里。

取而代之的是

        for(int i = 0 ; i < _wifiConnection.getListSSIDs().size(); i++){
            if(_wifiConnection.getListSSIDs().get(i).equals(ssid)){
                flag = true;
                break;
            }
        }

与

        flag = _wifiConnection.hasSSID(String ssid);

  public boolean hasSSID(String ssid) {
        for (int i = 0; i < scanResults.size(); i++) {
            if (ssid.equals(scanResults.get(i).SSID)) {
                return true;
            }
        }
        return false;
    }

内存不足错误的问题

1 个答案: