java file:
package com.example.calculator3;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
Button btn1, btn2, btn3, btn4, btn5, btn6, btn7, btn8, btn9, btn0;
Button btnPlus, btnMinus, btnMul, btnDiv, btnClr, btnEql;
boolean isPlus, isMinus, isDivide, isMul;
double val1, val2;
EditText tvResult;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnPlus = findViewById(R.id.btnPlus);
btnMinus = findViewById(R.id.btnMinus);
btnMul = findViewById(R.id.btnMul);
btnDiv = findViewById(R.id.btnDiv);
btn1 = findViewById(R.id.btn1);
btn2 = findViewById(R.id.btn2);
btn3 = findViewById(R.id.btn3);
btn4 = findViewById(R.id.btn4);
btn5 = findViewById(R.id.btn5);
btn6 = findViewById(R.id.btn6);
btn7 = findViewById(R.id.btn7);
btn8 = findViewById(R.id.btn8);
btn9 = findViewById(R.id.btn9);
btn0 = findViewById(R.id.btn0);
tvResult = findViewById(R.id.tvResult);
btn0.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String result = tvResult.getText() + "0";
tvResult.setText(result);
}
});
btn1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String result = tvResult.getText() + "1";
tvResult.setText(result);
}
});
btn2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String result = tvResult.getText() + "2";
tvResult.setText(result);
}
});
btn3.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String result = tvResult.getText() + "3";
tvResult.setText(result);
}
});
btn4.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String result = tvResult.getText() + "4";
tvResult.setText(result);
}
});
btn5.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String result = tvResult.getText() + "5";
tvResult.setText(result);
}
});
btn6.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String result = tvResult.getText() + "6";
tvResult.setText(result);
}
});
btn7.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String result = tvResult.getText() + "7";
tvResult.setText(result);
}
});
btn8.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String result = tvResult.getText() + "8";
tvResult.setText(result);
}
});
btn9.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String result = tvResult.getText() + "9";
tvResult.setText(result);
}
});
btnPlus.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (tvResult.getText() == null) {
tvResult.setText("");
}
val1 = Double.parseDouble(tvResult.getText().toString());
isPlus = true;
tvResult.setText(null);
}
});
btnMinus.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (tvResult.getText() == null) {
tvResult.setText("");
}
val1 = Double.parseDouble(tvResult.getText().toString());
isMinus = true;
tvResult.setText(null);
}
});
btnDiv.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (tvResult.getText() == null) {
tvResult.setText("");
}
val1 = Double.parseDouble(tvResult.getText().toString());
isDivide = true;
tvResult.setText(null);
}
});
btnMul.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (tvResult.getText() == null) {
tvResult.setText("");
}
val1 = Double.parseDouble(tvResult.getText().toString());
isMul = true;
tvResult.setText(null);
}
});
btnEql.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
val2 = Float.parseFloat(tvResult.getText().toString());
if (isPlus) {
tvResult.setText(val1 + val2 + "");
isPlus = false;
} else if (isMinus) {
tvResult.setText((val1 - val2) + "");
isMinus = false;
} else if (isMul) {
tvResult.setText((val1 * val2) + "");
isMul = false;
} else if (isDivide) {
tvResult.setText((val1 / val2) + "");
isDivide = false;
}
}
});
btnClr.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
tvResult.setText("");
val1 = 0.0;
val2 = 0.0;
}
});
}
}