Project

package com.example.scientificcalculator;

import androidx.appcompat.app.AppCompatActivity;

import android.annotation.SuppressLint;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

TextView input, signBox;

String sign, value1, value2;
Double num1, num2, result;
boolean hasDot;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

input = (TextView) findViewById(R.id.input);
signBox = (TextView) findViewById(R.id.sign);

hasDot = false;

}

@SuppressLint("SetTextI18n")
public void btnClick_0(View view) {
input.setText(input.getText() + "0");
}

@SuppressLint("SetTextI18n")
public void btnClick_1(View view) {
input.setText(input.getText() + "1");
}

@SuppressLint("SetTextI18n")
public void btnClick_2(View view) {
input.setText(input.getText() + "2");
}

@SuppressLint("SetTextI18n")
public void btnClick_3(View view) {
input.setText(input.getText() + "3");
}

@SuppressLint("SetTextI18n")
public void btnClick_4(View view) {
input.setText(input.getText() + "4");
}

@SuppressLint("SetTextI18n")
public void btnClick_5(View view) {
input.setText(input.getText() + "5");
}

@SuppressLint("SetTextI18n")
public void btnClick_6(View view) {
input.setText(input.getText() + "6");
}

@SuppressLint("SetTextI18n")
public void btnClick_7(View view) {
input.setText(input.getText() + "7");
}

@SuppressLint("SetTextI18n")
public void btnClick_8(View view) {
input.setText(input.getText() + "8");
}

@SuppressLint("SetTextI18n")
public void btnClick_9(View view) {
input.setText(input.getText() + "9");
}

@SuppressLint("SetTextI18n")
public void btnClick_dot(View view) {
if (!hasDot) {
if (input.getText().equals("")) {

input.setText("0.");
} else {

input.setText(input.getText() + ".");
}

hasDot = true;
}

}

public void btnClick_add(View view) {
sign = "+";
value1 = input.getText().toString();
input.setText(null);
signBox.setText("+");
hasDot = false;
}

public void btnClick_subtract(View view) {
sign = "-";
value1 = input.getText().toString();
input.setText(null);
signBox.setText("-");
hasDot = false;
}

public void btnClick_multiply(View view) {
sign = "*";
value1 = input.getText().toString();
input.setText(null);
signBox.setText("×");
hasDot = false;
}

public void btnClick_divide(View view) {
sign = "/";
value1 = input.getText().toString();
input.setText(null);
signBox.setText("÷");
hasDot = false;
}

@SuppressLint("SetTextI18n")
public void btnClick_log(View view) {
sign = "log";
input.setText(null);
signBox.setText("log");
hasDot = false;
}

@SuppressLint("SetTextI18n")
public void btnClick_ln(View view) {
sign = "ln";
input.setText(null);
signBox.setText("ln");
hasDot = false;
}

public void btnClick_power(View view) {
sign = "power";
value1 = input.getText().toString();
input.setText(null);
hasDot = false;
signBox.setText("xⁿ");
}

public void btnClick_factorial(View view) {
sign = "factorial";
input.setText(null);
hasDot = false;
signBox.setText("!");
}

@SuppressLint("SetTextI18n")
public void btnClick_sin(View view) {
sign = "sin";
input.setText(null);
hasDot = false;
signBox.setText("sin");
}

@SuppressLint("SetTextI18n")
public void btnClick_cos(View view) {
sign = "cos";
input.setText(null);
hasDot = false;
signBox.setText("cos");
}

@SuppressLint("SetTextI18n")
public void btnClick_tan(View view) {
sign = "tan";
input.setText(null);
hasDot = false;
signBox.setText("tan");
}

public void btnClick_root(View view) {
sign = "root";
input.setText(null);
hasDot = false;
signBox.setText("√");
}

@SuppressLint("SetTextI18n")
public void btnClick_equal(View view) {
if (sign == null) {
signBox.setText("Error!");
} else if (input.getText().equals("")) {
signBox.setText("Error!");
} else if ((sign.equals("+") || sign.equals("-") || sign.equals("*") || sign.equals("/")) && value1.equals("")) {
signBox.setText("Error!");
} else {
switch (sign) {
default:
break;
case "log":
value1 = input.getText().toString();
num1 = Double.parseDouble(value1);
input.setText(Math.log10(num1) + "");
sign = null;
signBox.setText(null);
break;
case "ln":
value1 = input.getText().toString();
num1 = Double.parseDouble(value1);
input.setText(Math.log(num1) + "");
sign = null;
signBox.setText(null);
break;
case "power":
num1 = Double.parseDouble((value1));
value2 = input.getText().toString();
num2 = Double.parseDouble(value2);
input.setText(Math.pow(num1, num2) + "");
sign = null;
signBox.setText(null);
break;
case "root":
value1 = input.getText().toString();
num1 = Double.parseDouble((value1));
input.setText(Math.sqrt(num1) + "");
sign = null;
signBox.setText(null);
break;
case "factorial":
value1 = input.getText().toString();
num1 = Double.parseDouble((value1));
int i = Integer.parseInt(value1) - 1;

while (i > 0) {
num1 = num1 * i;
i--;
}

input.setText(num1 + "");
sign = null;
signBox.setText(null);
break;
case "sin":
value1 = input.getText().toString();
num1 = Double.parseDouble((value1));
input.setText(Math.sin(num1) + "");
sign = null;
signBox.setText(null);
break;
case "cos":
value1 = input.getText().toString();
num1 = Double.parseDouble((value1));
input.setText(Math.cos(num1) + "");
sign = null;
signBox.setText(null);
break;
case "tan":
value1 = input.getText().toString();
num1 = Double.parseDouble((value1));
input.setText(Math.tan(num1) + "");
sign = null;
signBox.setText(null);
break;
case "+":
value2 = input.getText().toString();
num1 = Double.parseDouble(value1);
num2 = Double.parseDouble(value2);
result = num1 + num2;
input.setText(result + "");
sign = null;
signBox.setText(null);
break;
case "-":
value2 = input.getText().toString();
num1 = Double.parseDouble(value1);
num2 = Double.parseDouble(value2);
result = num1 - num2;
input.setText(result + "");
sign = null;
signBox.setText(null);
break;
case "*":
value2 = input.getText().toString();
num1 = Double.parseDouble(value1);
num2 = Double.parseDouble(value2);
result = num1 * num2;
input.setText(result + "");
sign = null;
signBox.setText(null);
break;
case "/":
value2 = input.getText().toString();
num1 = Double.parseDouble(value1);
num2 = Double.parseDouble(value2);
result = num1 / num2;
input.setText(result + "");
sign = null;
signBox.setText(null);
break;
}

}
}

public void btnClick_delete(View view) {
if (input.getText().equals("")) {
input.setText(null);
} else {
int len = input.getText().length();
String s = input.getText().toString();
if (s.charAt(len - 1) == '.') {
hasDot = false;
input.setText(input.getText().subSequence(0, input.getText().length() - 1));

} else {
input.setText(input.getText().subSequence(0, input.getText().length() - 1));
}
}
}

public void btnClick_clear(View view) {

input.setText(null);
signBox.setText(null);
value1 = null;
value2 = null;
sign = null;
hasDot = false;
}

}