calculator in android

main.xml

android:layout_width="fill_parent"

android:layout_height="fill_parent" >

android:id="@+id/txtResultId"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:editable="false"

android:gravity="right" />

android:id="@+id/tableId"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_below="@id/txtResultId" android:layout_marginTop="60dp">

android:id="@+id/btnNum7Id"

android:text="7"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_weight="1" />

android:id="@+id/btnNum8Id"

android:text="8"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_weight="1" />

android:id="@+id/btnNum9Id"

android:text="9"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_weight="1" />

android:id="@+id/btnDivId"

android:text="÷"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_weight="1" />

android:id="@+id/btnNum4Id"

android:text="4"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_weight="1" />

android:id="@+id/btnNum5Id"

android:text="5"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_weight="1" />

android:id="@+id/btnNum6Id"

android:text="6"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_weight="1" >

android:id="@+id/btnMulId"

android:text="×"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_weight="1" >

android:id="@+id/btnNum1Id"

android:text="1"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_weight="1" />

android:id="@+id/btnNum2Id"

android:text="2"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_weight="1" >

android:id="@+id/btnNum3Id"

android:text="3"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_weight="1" >

android:id="@+id/btnSubId"

android:text="-"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_weight="1" >

android:id="@+id/btnNum0Id"

android:text="0"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_weight="1" >

android:id="@+id/btnClearId"

android:text="C"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_weight="1" >

android:id="@+id/btnEqualId"

android:text="="

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_weight="1" >

android:id="@+id/btnAddId"

android:text="+"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_weight="1" >

calc.java

package com.exam;

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 calc extends Activity implements OnClickListener {

private EditText txtResult; // Reference to EditText of result

private int result = 0; // Result of computation

private String inStr = "0"; // Current input string

// Previous operator: '+', '-', '*', '/', '=' or ' ' (no operator)

private char lastOperator = ' ';

/** Called when the activity is first created. */

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

// Retrieve a reference to the EditText field for displaying the result.

txtResult = (EditText)findViewById(R.id.txtResultId);

txtResult.setText("0");

// Register listener (this class) for all the buttons

((Button)findViewById(R.id.btnNum0Id)).setOnClickListener(this);

((Button)findViewById(R.id.btnNum1Id)).setOnClickListener(this);

((Button)findViewById(R.id.btnNum2Id)).setOnClickListener(this);

((Button)findViewById(R.id.btnNum3Id)).setOnClickListener(this);

((Button)findViewById(R.id.btnNum4Id)).setOnClickListener(this);

((Button)findViewById(R.id.btnNum5Id)).setOnClickListener(this);

((Button)findViewById(R.id.btnNum6Id)).setOnClickListener(this);

((Button)findViewById(R.id.btnNum7Id)).setOnClickListener(this);

((Button)findViewById(R.id.btnNum8Id)).setOnClickListener(this);

((Button)findViewById(R.id.btnNum9Id)).setOnClickListener(this);

((Button)findViewById(R.id.btnAddId)).setOnClickListener(this);

((Button)findViewById(R.id.btnSubId)).setOnClickListener(this);

((Button)findViewById(R.id.btnMulId)).setOnClickListener(this);

((Button)findViewById(R.id.btnDivId)).setOnClickListener(this);

((Button)findViewById(R.id.btnClearId)).setOnClickListener(this);

((Button)findViewById(R.id.btnEqualId)).setOnClickListener(this);

}

// On-click event handler for all the buttons

@Override

public void onClick(View view) {

switch (view.getId()) {

// Number buttons: '0' to '9'

case R.id.btnNum0Id:

case R.id.btnNum1Id:

case R.id.btnNum2Id:

case R.id.btnNum3Id:

case R.id.btnNum4Id:

case R.id.btnNum5Id:

case R.id.btnNum6Id:

case R.id.btnNum7Id:

case R.id.btnNum8Id:

case R.id.btnNum9Id:

String inDigit = ((Button)view).getText().toString();

if (inStr.equals("0")) {

inStr = inDigit; // no leading zero

} else {

inStr += inDigit; // accumulate input digit

}

txtResult.setText(inStr);

// Clear buffer if last operator is '='

if (lastOperator == '=') {

result = 0;

lastOperator = ' ';

}

break;

// Operator buttons: '+', '-', '*', '/' and '='

case R.id.btnAddId:

compute();

lastOperator = '+';

break;

case R.id.btnSubId:

compute();

lastOperator = '-';

break;

case R.id.btnMulId:

compute();

lastOperator = '*';

break;

case R.id.btnDivId:

compute();

lastOperator = '/';

break;

case R.id.btnEqualId:

compute();

lastOperator = '=';

break;

// Clear button

case R.id.btnClearId:

result = 0;

inStr = "0";

lastOperator = ' ';

txtResult.setText("0");

break;

}

}

// User pushes '+', '-', '*', '/' or '=' button.

// Perform computation on the previous result and the current input number,

// based on the previous operator.

private void compute() {

int inNum = Integer.parseInt(inStr);

inStr = "0";

if (lastOperator == ' ') {

result = inNum;

} else if (lastOperator == '+') {

result += inNum;

} else if (lastOperator == '-') {

result -= inNum;

} else if (lastOperator == '*') {

result *= inNum;

} else if (lastOperator == '/') {

result /= inNum;

} else if (lastOperator == '=') {

// Keep the result for the next operation

}

txtResult.setText(String.valueOf(result));

}

}