java - App crashing during onTextChanged() -
this question has answer here:
- what nullpointerexception, , how fix it? 12 answers
i making simple notes app sqlite. has 2 activities , helper class sqlite. when click on example note(akhilesh chobey) in mainactivity.java, , try edit in main2activity.java application crashes.
main activity:
public class mainactivity extends appcompatactivity { listview noteslistview; static arraylist<string> notesarraylist; arrayadapter<string> adapter; @override protected void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.activity_main); noteslistview = (listview) findviewbyid(r.id.noteslistview); notesarraylist = new arraylist<string>(); notesarraylist.add("akhilesh chobey"); adapter = new arrayadapter<string>(this, android.r.layout.simple_list_item_1, notesarraylist); noteslistview.setadapter(adapter); noteslistview.setonitemclicklistener(new adapterview.onitemclicklistener() { @override public void onitemclick(adapterview<?> adapterview, view view, int i, long l) { intent intent = new intent(getapplicationcontext(), main2activity.class); intent.putextra("noteposition", i); startactivity(intent); } }); } } main2activity:
public class main2activity extends appcompatactivity implements textwatcher { databaseoperations mydb; edittext editnote; @override protected void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.activity_main2); editnote = (edittext) findviewbyid(r.id.noteedittext); mydb = new databaseoperations(main2activity.this); intent intent = getintent(); int position = intent.getintextra("noteposition", -1); if(position != -1){ editnote.settext(mainactivity.notesarraylist.get(position)); } editnote.addtextchangedlistener(this); } @override public void ontextchanged(charsequence charsequence, int i, int i1, int i2) { if (mydb == null){ boolean isinserted = mydb.insertdata(editnote.gettext().tostring()); if(isinserted){ toast.maketext(getapplicationcontext(), "inserted", toast.length_short).show(); }else { toast.maketext(getapplicationcontext(), "error", toast.length_short).show(); } } } helper class:
public class databaseoperations extends sqliteopenhelper { public static final string databasename = "notes.db"; public static final string tablename = "notes"; public static final string col1 = "text"; public databaseoperations(context context) { super(context, databasename, null, 1); } @override public void oncreate(sqlitedatabase db) { db.execsql("create table " + tablename + " (text text primary key autoincrement) "); } @override public void onupgrade(sqlitedatabase db, int i, int i1) { db.execsql("drop table if exists " + tablename); oncreate(db); } public boolean insertdata(string note){ sqlitedatabase db = this.getwritabledatabase(); contentvalues contentvalues = new contentvalues(); contentvalues.put(col1, note); long result = db.insert(tablename, null, contentvalues); if(result == -1){ return false; }else { return true; } } } log:
06-29 17:23:34.996 2231-2231/com.akhileshchobey.mynotes e/androidruntime: fatal exception: main process: com.akhileshchobey.mynotes, pid: 2231 java.lang.nullpointerexception: attempt invoke virtual method 'boolean com.akhileshchobey.mynotes.databaseoperations.insertdata(java.lang.string)' on null object reference @ com.akhileshchobey.mynotes.main2activity.ontextchanged(main2activity.java:39) @ android.widget.textview.sendontextchanged(textview.java:7746) @ android.widget.textview.handletextchanged(textview.java:7806) @ android.widget.textview$changewatcher.ontextchanged(textview.java:9724) @ android.text.spannablestringbuilder.sendtextchanged(spannablestringbuilder.java:964) @ android.text.spannablestringbuilder.replace(spannablestringbuilder.java:515) @ android.text.spannablestringbuilder.replace(spannablestringbuilder.java:454) @ android.text.spannablestringbuilder.replace(spannablestringbuilder.java:33) @ android.view.inputmethod.baseinputconnection.replacetext(baseinputconnection.java:685) @ android.view.inputmethod.baseinputconnection.setcomposingtext(baseinputconnection.java:445) @ com.android.internal.view.iinputconnectionwrapper.executemessage(iinputconnectionwrapper.java:340) @ com.android.internal.view.iinputconnectionwrapper$myhandler.handlemessage(iinputconnectionwrapper.java:78) @ android.os.handler.dispatchmessage(handler.java:102) @ android.os.looper.loop(looper.java:135) @ android.app.activitythread.main(activitythread.java:5264) @ java.lang.reflect.method.invoke(native method) @ java.lang.reflect.method.invoke(method.java:372) @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:900) @ com.android.internal.os.zygoteinit.main(zygoteinit.java:695)
don't initialize mydb = null;,
initialize mydb in oncreate() of main2activity
mydb = new databaseoperations(main2activity.this); edit
you have initialized mydb, , not null. have change below in ontextchanged() method.
if (mydb == null) to
if (mydb != null)
Comments
Post a Comment