Android实现简单计算器界面

<?xml version="1.0" encoding="utf-8"?>
<gridlayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:rowcount="6"
 android:columncount="4"
 android:id="@+id/root">
 
 <textview
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:layout_columnspan="4"
 android:textsize="50sp"
 android:layout_marginleft="2pt"
 android:layout_marginright="2pt"
 android:padding="3pt"
 android:layout_gravity="right"
 android:background="#eee"
 android:textcolor="#000"
 android:text="0" />
 
 <button
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:layout_columnspan="4"
 android:text="清除"/>
 
</gridlayout>

package learn.li.com.learnthree;
 
import android.os.handler;
import android.os.message;
import android.support.v7.app.appcompatactivity;
import android.os.bundle;
import android.view.gravity;
import android.widget.button;
import android.widget.gridlayout;
import android.widget.textview;
 
import java.util.timer;
import java.util.timertask;
 
public class mainactivity extends appcompatactivity {
 gridlayout gridlayout;
 string[] chars = new string[]{
  "7","8","9","÷",
  "4","5","6","x",
  "1","2","3","-",
  ".","0","=","="
 };
 @override
 protected void oncreate(bundle savedinstancestate) {
 super.oncreate(savedinstancestate);
 setcontentview(r.layout.activity_main);
 gridlayout = (gridlayout)findviewbyid(r.id.root);
 for(int i = 0;i < chars.length;i++){
  button bn = new button(this);
  bn.settext(chars[i]);
  bn.settextsize(40);
  bn.setpadding(5,35,5,35);
  gridlayout.spec rowspec = gridlayout.spec(i/4 + 2);
  gridlayout.spec columnspec = gridlayout.spec(i%4);
  gridlayout.layoutparams params = new gridlayout.layoutparams(rowspec,columnspec);
  params.setgravity(gravity.fill);
  gridlayout.addview(bn,params);
 
 }
 }
}