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);
 
 }
 }
}