ERROR/AndroidRuntime(363): java.lang.RuntimeException: Unable to start activity ComponentInfo{dongguk.ac/dongguk.ac.rssiScan}: java.lang.NullPointerException
ERROR/AndroidRuntime(363): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
ERROR/AndroidRuntime(363): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
ERROR/AndroidRuntime(363): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
ERROR/AndroidRuntime(363): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
ERROR/AndroidRuntime(363): at android.os.Handler.dispatchMessage(Handler.java:99)
ERROR/AndroidRuntime(363): at android.os.Looper.loop(Looper.java:123)
ERROR/AndroidRuntime(363): at android.app.ActivityThread.main(ActivityThread.java:4627)
ERROR/AndroidRuntime(363): at java.lang.reflect.Method.invokeNative(Native Method)
ERROR/AndroidRuntime(363): at java.lang.reflect.Method.invoke(Method.java:521)
ERROR/AndroidRuntime(363): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
ERROR/AndroidRuntime(363): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
ERROR/AndroidRuntime(363): at dalvik.system.NativeStart.main(Native Method)
ERROR/AndroidRuntime(363): Caused by: java.lang.NullPointerException
ERROR/AndroidRuntime(363): at dongguk.ac.rssiScan.onCreate(rssiScan.java:40)
ERROR/AndroidRuntime(363): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
ERROR/AndroidRuntime(363): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
ERROR/AndroidRuntime(363): ... 11 more
이클립스 상에 에러는 없는데 에뮬레이터 실행시 접속이 되지않습니다.
LogCat 에러 를 보니 이렇게 나오는데 잘 이해가 가지않아 올립니다.
고수님들의 가르침을 좀 받고 싶습니다.
ERROR/AndroidRuntime(363): at dongguk.ac.rssiScan.onCreate(rssiScan.java:40)
이부분이 자꾸 선택이되던데... 어떻게 수정을 해야할지 모르겟습니다..
해당위치는 노란색으로 가르켜놓겟습니다.
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// Setup UI
textStatus = (TextView) findViewById(R.id.textStatus);
buttonScan = (Button) findViewById(R.id.buttonScan);
buttonScan.setOnClickListener(this);
// Setup WiFi
wifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);
// List<ScanResult>
List<ScanResult> results = wifiDemo.wifi.getScanResults();
ArrayList<Integer> maxsignal = new ArrayList <Integer> ();
ScanResult bestSignal = null;
for (ScanResult result : results) {
if (bestSignal == null
|| WifiManager.compareSignalLevel(bestSignal.level, result.level) < 0){
maxsignal.add(result.level);
bestSignal = result;
}
}
java.util.Collections.sort(maxsignal);
textStatus.append("\n\nWiFi Status: " + maxsignal.toString());
// Get WiFi status
WifiInfo info = wifi.getConnectionInfo();
textStatus.append("\n\nWiFi Status: " +
"\nSSID : " + info.getSSID() +
"\nMacAddress : " + info.getMacAddress() +
"\nRssi : " + info.getRssi());
// List available networks
List<WifiConfiguration> configs = wifi.getConfiguredNetworks();
for (WifiConfiguration config : configs) {
textStatus.append("\n\n" + config.SSID);
}
// Register Broadcast Receiver
if (receiver == null)
receiver = new WiFiScanReceiver(this);
registerReceiver(receiver, new IntentFilter(
WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
Log.d(TAG, "onCreate()");
}




wifiDemo가 무슨 객체인지는 모르지만
흔한 런타임 null오류네요.
wifi가 null이면 아래코드 실행안되게 하면 되지 않을까요