I want to make a Scientific Calculator(Android app) but some problems appears. I don't know Java but I understand the code because I know C++. I had modified the code of a normal Calculator into a Scientific Calculator but the code doesn't seems to work. Only the basic functions like +,-,*,/ work but the functions which I added like Sin,Cos,Tan,Sqrt,Pow,Exp etc. doesn't seems to work when I use those functions the app crashes. This is my source code.
MainActivity.java
package com.example.anant.scientificcalculator;
import android.databinding.DataBindingUtil;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import static java.lang.Math.*;
import java.text.DecimalFormat;
import com.example.anant.scientificcalculator.databinding.MainActivityBinding;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
private MainActivityBinding binding;
private static final char FACT = '!';
private static final char POWER = '^';
private static final String SQRT = "SQRT";
private static final String SIN = "SIN";
private static final String COS = "COS";
private static final String TAN = "TAN";
private static final String LOG = "LOG";
private static final char LEFTC = '(';
private static final char RIGHTC = ')';
private static final String EXP = "EXP";
private static final String PIE = "PIE";
private static final char ADD = '+';
private static final char SUBTRACT = '-';
private static final char MULTIPlY = '*';
private static final char DIVIDE = '/';
private char CURRENT_ACTION;
private String ADVANCE_ACTION;
private double valueOne = Double.NaN;
private double valueTwo;
private double valueTemp;
private DecimalFormat decimalFormat;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
decimalFormat = new DecimalFormat("#.##########");
binding = DataBindingUtil.setContentView(this, R.layout.main_activity);
binding.buttonDot.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view){
binding.editText.setText(binding.editText.getText() + ".");
}
});
binding.buttonZero.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view){
binding.editText.setText(binding.editText.getText() + "0");
}
});
binding.buttonOne.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view){
binding.editText.setText(binding.editText.getText() + "1");
}
});
binding.buttonTwo.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view){
binding.editText.setText(binding.editText.getText() + "2");
}
});
binding.buttonThree.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view){
binding.editText.setText(binding.editText.getText() + "3");
}
});
binding.buttonFour.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view){
binding.editText.setText(binding.editText.getText() + "4");
}
});
binding.buttonFive.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view){
binding.editText.setText(binding.editText.getText() + "5");
}
});
binding.buttonSix.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view){
binding.editText.setText(binding.editText.getText() + "6");
}
});
binding.buttonSeven.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view){
binding.editText.setText(binding.editText.getText() + "7");
}
});
binding.buttonEight.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view){
binding.editText.setText(binding.editText.getText() + "8");
}
});
binding.buttonNine.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view){
binding.editText.setText(binding.editText.getText() + "9");
}
});
binding.buttonLeftC.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view){
binding.editText.setText(binding.editText.getText() + "(");
}
});
binding.buttonRightC.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view){
binding.editText.setText(binding.editText.getText() + ")");
}
});
binding.buttonExp.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view){
computeCalculation();
ADVANCE_ACTION = EXP;
binding.infoTextView.setText(decimalFormat.format(valueOne) + "EXP");
binding.editText.setText(null);
}
});
binding.buttonPie.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view){
computeCalculation();
ADVANCE_ACTION = PIE;
binding.infoTextView.setText(decimalFormat.format(valueOne) + "PIE");
binding.editText.setText(null);
}
});
binding.buttonAdd.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
computeCalculation();
CURRENT_ACTION = ADD;
binding.infoTextView.setText(decimalFormat.format(valueOne) + "+");
binding.editText.setText(null);
}
});
binding.buttonSubtract.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
computeCalculation();
CURRENT_ACTION = SUBTRACT;
binding.infoTextView.setText(decimalFormat.format(valueOne) + "-");
binding.editText.setText(null);
}
});
binding.buttonMultiply.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
computeCalculation();
CURRENT_ACTION = MULTIPlY;
binding.infoTextView.setText(decimalFormat.format(valueOne) + "*");
binding.editText.setText(null);
}
});
binding.buttonDivide.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
computeCalculation();
CURRENT_ACTION = DIVIDE;
binding.infoTextView.setText(decimalFormat.format(valueOne) + "/");
binding.editText.setText(null);
}
});
binding.buttonFact.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
computeCalculation();
CURRENT_ACTION = FACT;
binding.infoTextView.setText(decimalFormat.format(valueOne) + "!");
binding.editText.setText(null);
}
});
binding.buttonPow.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
computeCalculation();
CURRENT_ACTION = POWER;
binding.infoTextView.setText(decimalFormat.format(valueOne) + "^");
binding.editText.setText(null);
}
});
binding.buttonSqrt.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
computeCalculation();
ADVANCE_ACTION = SQRT;
binding.infoTextView.setText("SQRT(" + decimalFormat.format(valueOne) + ")");
binding.editText.setText(null);
}
});
binding.buttonSine.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
computeCalculation();
ADVANCE_ACTION = SIN;
binding.infoTextView.setText("SIN(" + decimalFormat.format(valueOne) + ")");
binding.editText.setText(null);
}
});
binding.buttonCosine.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
computeCalculation();
ADVANCE_ACTION = COS;
binding.infoTextView.setText("COS(" + decimalFormat.format(valueOne) + ")");
binding.editText.setText(null);
}
});
binding.buttonTangent.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
computeCalculation();
ADVANCE_ACTION = TAN;
binding.infoTextView.setText("TAN(" + decimalFormat.format(valueOne) + ")");
binding.editText.setText(null);
}
});
binding.buttonLog.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
computeCalculation();
ADVANCE_ACTION = LOG;
binding.infoTextView.setText("LOG(" + decimalFormat.format(valueOne) + ")");
binding.editText.setText(null);
}
});
binding.buttonEqual.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
computeCalculation();
binding.infoTextView.setText(binding.infoTextView.getText().toString() +
decimalFormat.format(valueTwo) + " = " + decimalFormat.format(valueOne));
valueOne = Double.NaN;
CURRENT_ACTION = '0';
}
});
binding.buttonClear.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if(binding.editText.getText().length() > 0) {
CharSequence currentText = binding.editText.getText();
binding.editText.setText(currentText.subSequence(0, currentText.length()-1));
}
else {
valueOne = Double.NaN;
valueTwo = Double.NaN;
binding.editText.setText("");
binding.infoTextView.setText("");
}
}
});
}
private void computeCalculation() {
if(!Double.isNaN(valueOne)) {
valueTwo = Double.parseDouble(binding.editText.getText().toString());
binding.editText.setText(null);
if(CURRENT_ACTION == ADD)
valueOne = this.valueOne + valueTwo;
else if(CURRENT_ACTION == SUBTRACT)
valueOne = this.valueOne - valueTwo;
else if(CURRENT_ACTION == MULTIPlY)
valueOne = this.valueOne * valueTwo;
else if(CURRENT_ACTION == DIVIDE)
valueOne = this.valueOne / valueTwo;
else if(CURRENT_ACTION == FACT)
{
valueTemp = this.valueOne;
int i,valueThree=1;
for(i=(int) valueTemp;i>0;i--) //type conversion
{
valueThree *= i;
}
valueOne = valueThree;
}
else if(CURRENT_ACTION == POWER) {
valueTemp = this.valueOne;
valueTemp = Math.pow(valueOne, valueTwo);
valueOne = valueTemp;
}
else if(ADVANCE_ACTION == SQRT) {
valueTemp = this.valueOne;
valueOne = Math.sqrt(valueTemp);
}
else if(ADVANCE_ACTION == SIN) {
valueTemp = this.valueOne;
valueOne = Math.sin(valueTemp);
}
else if(ADVANCE_ACTION == COS) {
valueTemp = this.valueOne;
valueOne = Math.cos(valueTemp);
}
else if(ADVANCE_ACTION == TAN) {
valueTemp = this.valueOne;
valueOne = Math.tan(valueTemp);
}
else if(ADVANCE_ACTION == LOG) {
valueTemp = this.valueOne;
valueOne = Math.log(valueTemp);
}
else if(ADVANCE_ACTION == PIE) {
valueTemp = this.valueOne;
valueTemp = Math.PI;
valueOne = valueTemp;
}
else if(ADVANCE_ACTION == EXP) {
valueTemp = this.valueOne;
valueTemp = Math.E;
valueOne = valueTemp;
}
}
else {
try {
valueOne = Double.parseDouble(binding.editText.getText().toString());
}
catch (Exception e){}
}
}
}
Can anyone tell me why my app keeps on crashing?
main_activity.xml
<?xml version="1.0" encoding="utf-8"?>
<layout>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/main_activity"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.anant.scientificcalculator.MainActivity">
<TextView
android:id="@+id/infoTextView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="30dp"
android:textSize="30sp" />
<EditText
android:id="@+id/editText"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@id/infoTextView"
android:enabled="false"
android:gravity="bottom"
android:hint="0"
android:inputType="numberDecimal"
android:lines="2"
android:maxLines="2"
android:textAlignment="textEnd"
android:textColor="@android:color/black"
android:textSize="40sp" />
<Button
android:id="@+id/buttonFact"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/editText"
android:text="@string/buttonFact"
android:textSize="20sp" />
<Button
android:id="@+id/buttonPow"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/editText"
android:layout_toRightOf="@id/buttonFact"
android:text="@string/buttonPow"
android:textSize="20sp" />
<Button
android:id="@+id/buttonSqrt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/editText"
android:layout_toRightOf="@id/buttonPow"
android:text="@string/buttonSqrt"
android:textSize="20sp" />
<Button
android:id="@+id/buttonClear"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="@id/buttonSqrt"
android:layout_below="@id/editText"
android:text="@string/buttonClear"
android:textSize="20sp" />
<Button
android:id="@+id/buttonSine"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/buttonFact"
android:text="@string/buttonSine"
android:textSize="20sp" />
<Button
android:id="@+id/buttonCosine"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/buttonPow"
android:layout_toRightOf="@id/buttonSine"
android:text="@string/buttonCosine"
android:textSize="20sp" />
<Button
android:id="@+id/buttonTangent"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/buttonSqrt"
android:layout_toRightOf="@id/buttonCosine"
android:text="@string/buttonTangent"
android:textSize="20sp" />
<Button
android:id="@+id/buttonLog"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/buttonClear"
android:layout_toRightOf="@id/buttonTangent"
android:text="@string/buttonLog"
android:textSize="20sp" />
<Button
android:id="@+id/buttonLeftC"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/buttonSine"
android:text="@string/buttonLeftC"
android:textSize="20sp" />
<Button
android:id="@+id/buttonRightC"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/buttonCosine"
android:layout_toRightOf="@id/buttonLeftC"
android:text="@string/buttonRightC"
android:textSize="20sp" />
<Button
android:id="@+id/buttonExp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/buttonTangent"
android:layout_toRightOf="@id/buttonRightC"
android:text="@string/buttonExp"
android:textSize="20sp" />
<Button
android:id="@+id/buttonPie"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/buttonLog"
android:layout_toRightOf="@id/buttonExp"
android:text="@string/buttonPie"
android:textSize="20sp" />
<Button
android:id="@+id/buttonSeven"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/buttonLeftC"
android:text="@string/buttonSeven"
android:textSize="20sp" />
<Button
android:id="@+id/buttonEight"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/buttonRightC"
android:layout_toRightOf="@id/buttonSeven"
android:text="@string/buttonEight"
android:textSize="20sp" />
<Button
android:id="@+id/buttonNine"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/buttonExp"
android:layout_toRightOf="@id/buttonEight"
android:text="@string/buttonNine"
android:textSize="20sp" />
<Button
android:id="@+id/buttonFour"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/buttonSeven"
android:text="@string/buttonFour"
android:textSize="20sp" />
<Button
android:id="@+id/buttonFive"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/buttonEight"
android:layout_toRightOf="@id/buttonFour"
android:text="@string/buttonFive"
android:textSize="20sp" />
<Button
android:id="@+id/buttonSix"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/buttonNine"
android:layout_toRightOf="@id/buttonFive"
android:text="@string/buttonSix"
android:textSize="20sp" />
<Button
android:id="@+id/buttonOne"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/buttonFour"
android:text="@string/buttonOne"
android:textSize="20sp" />
<Button
android:id="@+id/buttonTwo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/buttonFive"
android:layout_toRightOf="@id/buttonOne"
android:text="@string/buttonTwo"
android:textSize="20sp" />
<Button
android:id="@+id/buttonThree"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/buttonSix"
android:layout_toRightOf="@id/buttonTwo"
android:text="@string/buttonThree"
android:textSize="20sp" />
<Button
android:id="@+id/buttonDot"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/buttonOne"
android:text="@string/buttonDot"
android:textSize="20sp" />
<Button
android:id="@+id/buttonZero"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/buttonTwo"
android:layout_toRightOf="@id/buttonDot"
android:text="@string/buttonZero"
android:textSize="20sp" />
<Button
android:id="@+id/buttonEqual"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignRight="@id/buttonNine"
android:layout_below="@id/buttonThree"
android:text="@string/buttonEqual"
android:textSize="20sp" />
<Button
android:id="@+id/buttonDivide"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignTop="@id/buttonNine"
android:layout_toRightOf="@id/buttonNine"
android:text="@string/buttonDIvide"
android:textSize="20sp" />
<Button
android:id="@+id/buttonMultiply"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignTop="@id/buttonSix"
android:layout_toRightOf="@id/buttonSix"
android:text="@string/buttonMultiply"
android:textSize="20sp" />
<Button
android:id="@+id/buttonSubtract"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignTop="@id/buttonThree"
android:layout_toRightOf="@id/buttonThree"
android:text="@string/buttonSubtract"
android:textSize="20sp" />
<Button
android:id="@+id/buttonAdd"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignTop="@id/buttonEqual"
android:layout_toRightOf="@id/buttonEqual"
android:text="@string/buttonAdd"
android:textSize="20sp" />
</RelativeLayout>
</layout>
I managed to run your code with minor changes.
The problem seems to be here:
private void computeCalculation() {
if(!Double.isNaN(valueOne)) {
valueTwo = Double.parseDouble(binding.editText.getText().toString());
binding.editText.setText(null);
If you check down below the Android Monitor after the crash you will see something like this:
04-10 13:01:01.531 20742-20742/com.johnurrutia.so_43315233 E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.johnurrutia.so_43315233, PID: 20742
java.lang.NumberFormatException: Invalid double: ""
at java.lang.StringToReal.invalidReal(StringToReal.java:63)
at java.lang.StringToReal.parseDouble(StringToReal.java:267)
at java.lang.Double.parseDouble(Double.java:301)
at com.johnurrutia.so_43315233.MainActivity.computeCalculation(MainActivity.java:303)
at com.johnurrutia.so_43315233.MainActivity.access$100(MainActivity.java:11)
...
It tells you have a FATAL EXCEPTION because of an ivalid double. Which you can track to MainActivity.java in line 303 (you will have a different line most likely).
With the debugger on that line you can check and see what is happening.
I think you are trying to convert an empty String to a Double.
The changes I did to run you code are the following.
1) In the layout file: a) Changed the layout tag with the android name space. b) Added an empty placeholder (not sure if its necessary or not)
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">
<data>
</data>
<RelativeLayout
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/main_activity"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.johnurrutia.so_43315233.MainActivity">
...
</layout>
c) In the EditText there is an alignment to "endText" that seems to be incompatible with the selected gravity so I just erased it.
d) As you haven't posted it, just make sure you have all your @string/stringname set in your res/values/string.xml file.
2) As you are working with Data Binding, check your Gradle App Module file. You have to have:
android {
...
dataBinding {
enabled = true
}
}
3) After that look at your files and check you see nothing in red.
4) Hit Build->Clean Project. And then Run.
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