<?xml version="1.0" encoding="utf-8"?> <EditText     android:id="@+id/editText1"     android:layout_width="match_parent"     android:layout_height="wrap_content"     android:ems="10" >     <requestFocus /> </EditText> <Button     android:id="@+id/button1"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:text="1" /> <Button     android:id="@+id/button2"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:text="2" /> <Button     android:id="@+id/button3"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:text="+" /> <Button     android:id="@+id/button4"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:text="=" />

package com.action; import android.R.integer; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.EditText; public class jspActivity extends Activity{ private Button bt1; private Button bt2; private Button btadd; private Button bteql; private EditText et; private int a; private int b; private String stra=""; private String fh; protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.jsp);     bt1=(Button) findViewById(R.id.button1);     bt2=(Button) findViewById(R.id.button2);     btadd=(Button) findViewById(R.id.button3);     bteql=(Button) findViewById(R.id.button4);     et=(EditText) findViewById(R.id.editText1);     bt1.setOnClickListener(new sum());     bt2.setOnClickListener(new sum());     btadd.setOnClickListener(new OnClickListener() {         @Override         public void onClick(View v) {             // TODO Auto-generated method stub             a=Integer.parseInt(et.getText().toString()) ;             et.setText("");             stra="";             fh=btadd.getText().toString();         }     });     bteql.setOnClickListener(new OnClickListener() {         @Override         public void onClick(View v) {             // TODO Auto-generated method stub             b=Integer.parseInt(et.getText().toString()) ;             et.setText("");             stra="";             if(fh.equals("+"))             {                 int c=a+b;                 et.setText(""+c);             }         }     }); } public class sum implements OnClickListener{     @Override     public void onClick(View v) {         // TODO Auto-generated method stub         switch (v.getId()) {         case R.id.button1:             stra+=bt1.getText();             et.setText(stra);             break;         case R.id.button2:             stra+=bt2.getText();             et.setText(stra);             break;         default:             break;         }     } } }