java.lang.NullPointerException: println needs a message
Problemi is in e.getMessage() what can return null and Log.e (String tag, String msg) will throws an new exception !!!!
Problem and solution:
LogCat:
Or you can using this code:
Problem and solution:
try {
int [] i = {1};
int z = i[5];
} catch (ArrayIndexOutOfBoundsException e) {
String s = e.toString(); // s == java.lang.ArrayIndexOutOfBoundsException
// try to testing String s for null value
if(s != null)
Log.e("bla", s);
else
Log.e("bla", "My error text 1");
String s2 = e.getMessage(); // s2 == null !!!!!!!
// you need to testing String s2 for null value , or you get FATAL EXCEPTION: main
// and application will be crashed
String s2 = e.getMessage(); // s2 == null !!!!!!!
if(s2 != null)
Log.e("bla2", e.getMessage());
else
Log.e("bla2", "My error text 2");
// this is OK
e.printStackTrace();
}
LogCat:
E/bla(855): java.lang.ArrayIndexOutOfBoundsException
E/bla2(855): My error text 2
W/System.err(855): java.lang.ArrayIndexOutOfBoundsException
W/System.err(855): at cz.okhelp.motion._MotionActivity.onTouchEvent(_MotionActivity.java:54)
W/System.err(855): at android.app.Activity.dispatchTouchEvent(Activity.java:2099)
W/System.err(855): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1675)
W/System.err(855): at android.view.ViewRoot.deliverPointerEvent(ViewRoot.java:2194)
W/System.err(855): at android.view.ViewRoot.handleMessage(ViewRoot.java:1878)
W/System.err(855): at android.os.Handler.dispatchMessage(Handler.java:99)
W/System.err(855): at android.os.Looper.loop(Looper.java:123)
W/System.err(855): at android.app.ActivityThread.main(ActivityThread.java:3683)
W/System.err(855): at java.lang.reflect.Method.invokeNative(Native Method)
W/System.err(855): at java.lang.reflect.Method.invoke(Method.java:507)
W/System.err(855): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
W/System.err(855): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
W/System.err(855): at dalvik.system.NativeStart.main(Native Method)
Or you can using this code:
try {
int [] i = {1};
int z = i[5];
} catch (Exception e) {
StringBuilder sb = new StringBuilder().append(e.getClass().getSimpleName());
if (e.getMessage() != null) {
sb.append("
");
sb.append(e.getMessage());
}
Log.e("err", sb.toString()); // E/err(336): ArrayIndexOutOfBoundsException
// this code write out all message
Log.e("myError", "methodName", e);
}
// E/myError(371): methodName
// E/myError(371): java.lang.ArrayIndexOutOfBoundsException
// E/myError(371): at cz.okhelp.motion._MotionActivity.onTouchEvent(_MotionActivity.java:54)
// E/myError(371): at android.app.Activity.dispatchTouchEvent(Activity.java:2099)
// E/myError(371): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1675)
// E/myError(371): at android.view.ViewRoot.deliverPointerEvent(ViewRoot.java:2194)
// E/myError(371): at android.view.ViewRoot.handleMessage(ViewRoot.java:1878)
// E/myError(371): at android.os.Handler.dispatchMessage(Handler.java:99)
// E/myError(371): at android.os.Looper.loop(Looper.java:123)
// E/myError(371): at android.app.ActivityThread.main(ActivityThread.java:3683)
// E/myError(371): at java.lang.reflect.Method.invokeNative(Native Method)
// E/myError(371): at java.lang.reflect.Method.invoke(Method.java:507)
// E/myError(371): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
// E/myError(371): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
// E/myError(371): at dalvik.system.NativeStart.main(Native Method)
396LW NO topic_id
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Další témata ....(Topics)
Important: Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB
Example of usage:
int layout = Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB ?
android.R.layout.simple_list_item_activated_1 :
android.R.layout.simple_list_item_1;
getListView().setChoiceMode(ListView.CHOICE_MODE_SINGLE);
getListView().setItemChecked(position, true);
Example of usage:
public void updateList() {
Context ctx = getActivity();
Notes notes = new Notes(ctx);
String[] from = { Notes.COLUMN_TITLE };
int[] to = { android.R.id.text1 };
int layout = Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB ?
android.R.layout.simple_list_item_activated_1 : android.R.layout.simple_list_item_1;
ListAdapter adapter = new SimpleCursorAdapter(ctx,
layout, notes.getNotes(), from,
to, 0);
setListAdapter(adapter);
notes.close();
}
/..................
@Override
public void onListItemClick(ListView l, View v, int position, long id) {
// Set the item as checked to be highlighted when in two-pane layout
getListView().setChoiceMode(ListView.CHOICE_MODE_SINGLE);
getListView().setItemChecked(position, true);
}
Warning in AndroidManifest.xml:
tag should specify a target API level (the highest verified version; when running on
later versions, compatibility behaviors may be enabled) with android:targetSdkVersion="?"
Solution:
later versions, compatibility behaviors may be enabled) with android:targetSdkVersion="?"
Solution:
<uses-sdk android:minSdkVersion="4"
android:targetSdkVersion="16" />
Foreach in Java basic example source code.
MainClass.java
MainClass.java
public class MainClass {
public static void main(String[] arg) {
String[] arrayOfString = { "Hello", "people", "hello", "world!" };
for (String s : arrayOfString)
System.out.println(s);
}
}
Try add to AndroidManifest.xml configChanges for your Activity
android:configChanges="keyboardHidden|orientation|screenSize"
android:configChanges="keyboardHidden|orientation|screenSize"
<activity android:name=".MainActivity"
android:label="@string/app_name"
android:configChanges="keyboardHidden|orientation|screenSize"
>
Read file from URL to array of byte and convert to UTF-8 String Android examle source code.
URL urlLoc = new URL("//myweb.com/myfile.html");
URLConnection conexion = urlLoc.openConnection();
conexion.setConnectTimeout(4000);
conexion.setReadTimeout(1000);
conexion.connect();
// downlod the file
InputStream input = new BufferedInputStream(urlLoc
.openStream());
StringBuffer responseBuffer = new StringBuffer();
byte[] byteArray = new byte[1024];
while (input.read(byteArray) != -1)
{
String res = new String(byteArray, "UTF-8");
responseBuffer.append(res);
byteArray = null;
byteArray = new byte[1024];
}
String response = responseBuffer.toString().trim();
Editace: 2013-12-09 10:21:23
Počet článků v kategorii: 396
Url:java-lang-nullpointerexception-println-needs-a-message
