Android XML buttons -

i trying make calculator android. have started using xml make buttons , such , going reference them in java math. having trouble making them buttons instead of lines. understand weight sum, don't know if supposed using kind of thing. code following: (code has been updated)

<?xml version="1.0" encoding="utf-8"?> <linearlayout xmlns:android="http://schemas.android.com/apk/res/android"     android:layout_width="match_parent"     android:layout_height="wrap_content"     android:orientation="vertical" >      <textview     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:layout_gravity="center"     android:text="@string/total"     android:textsize="45sp"      android:id="@+id/calcdisplay"     />      <linearlayout         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:orientation="horizontal"      >      <button         android:id="@+id/number1"         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:gravity="center"         android:text="1"      />              <button         android:id="@+id/number2"         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:gravity="center"         android:text="2"       />        <button         android:id="@+id/number3"         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:gravity="center"       />      </linearlayout>      <linearlayout         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:orientation="horizontal"                 >      <button         android:id="@+id/number4"         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:gravity="center"      />              <button         android:id="@+id/number5"         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:gravity="center"       />              <button         android:id="@+id/number6"         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:gravity="center"      />         </linearlayout>      <linearlayout         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:orientation="horizontal"      >      <button         android:id="@+id/number7"         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:gravity="center"       />      <button         android:id="@+id/number8"         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:gravity="center"      />      <button         android:id="@+id/number9"         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:gravity="center"      />      </linearlayout>      <button         android:id="@+id/number0"         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:gravity="center"         android:layout_gravity="center_horizontal"          />   </linearlayout> 

try this:

 <button android:id="@+id/number1"     android:layout_width="match_parent"     android:layout_height="wrap_content"     android:gravity="center" />       

you want replace fill_parent match_parent, unless targeting api 7 or lower. if api 8 or higher use match_parent. also, want add android:text="my string here" each button otherwise wrap_content nothing more line since there nothing "wrap" around.

then in java can following in oncreate():

button number1 = (button) findviewbyid(r.id.number1); number1.setonclicklistener(new view.onclicklistener() {    public void onclick(view v) {       //do action stuff!!!    } }); 

i use lower case in xml, on occasion uppercase cause problems.