java - putExtra() not working for Button:onClick -

i have 2 activities , i'm trying put values first 1 second one. in first activity, created button onclick parameter.

<button     android:id="@+id/navibutton"     android:layout_width="match_parent"     android:layout_height="60dp"     android:text="navigate"     android:layout_alignparentbottom="true"     android:onclick="startnavigation"/> 

then created 2 methods in activity selecteddock: oncreate , startnavigation

public void startnavigation (view view) {     intent gpsintent = new intent(selecteddock.this, gpsactivity.class);     string xcorvalue = "what's wrong you?!";     gpsintent.putextra("selectedxcor", xcorvalue);     startactivity(gpsintent); 

in gpsactivity have:

public class gpsactivity extends appcompatactivity {  @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_gps);     textview xcortv = (textview) findviewbyid(r.id.textview2);     xcortv.settext(getintent().getextras().getstring("selectedxcor")); } } 

and in app see nothing. text. if remove .settext can see default value of textview. used tutorial , simple code works, mine.. not. wrong? have add selecteddock third activity in project , first , second, used intent.

gpsintent.putextra("selectedxcor", xcorvalue);  xcortv.settext(getintent().getextras().getstring("selectedxcor")); 

instead of hardcoding "selectedxcor", use final static variable in different class can use variable in whole application minimizing such mistakes.

make class named "intentkeys" , declare variable

public static final string keycore = "selectedxcor"; 

now use wherever want them,

gpsintent.putextra(intentkeys.keycore, xcorvalue);  xcortv.settext(getintent().getextras().getstring(intentkeys.keycore));