calculator

package com.example.admin.calculator;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

import org.w3c.dom.Text;

public class MainActivity extends AppCompatActivity {
    private TextView result;
    private EditText a;
    private EditText b;
    private Button add ;
    private Button sub;
    private Button mul;
    private Button div;



    @Override
    protected void onCreate(Bundle savedInstanceState) {


        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        result = (TextView)findViewById(R.id.textView);
        a = (EditText)findViewById(R.id.editText);
        b = (EditText)findViewById(R.id.editText2);



        add = (Button)findViewById(R.id.button);
        sub = (Button)findViewById(R.id.button2);
        mul = (Button)findViewById(R.id.button3);
        div = (Button)findViewById(R.id.button4);
        add.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                result.setText("");

                if(a.getText().toString().matches("") || b.getText().toString().matches("")){
                    result.setText("");
                }
                else {
                    double temp1 = Double.parseDouble(a.getText().toString());
                    double temp2 = Double.parseDouble(b.getText().toString());
                    double temp3 = temp1 + temp2;
                    result.setText("" + temp3);
                }
            }
        });

    }

//    public void add(View view) {
//        result.setText("");
//        double temp1 = Double.parseDouble(a.getText().toString());
//        double temp2 = Double.parseDouble(b.getText().toString());
//        double temp3 = temp1 + temp2;
//        if(a.getText().toString().matches("") || b.getText().toString().matches("")){
//            result.setText("");
//        }
//        else {
//            result.setText("" + temp3);
//        }
//    }

    public void sub(View view) {
        result.setText("");
        if(a.getText().equals("") || b.getText().equals("")){
            result.setText("");
        }
        else {
            double temp1 = Double.parseDouble(a.getText().toString());
            double temp2 = Double.parseDouble(b.getText().toString());
            double temp3 = temp1 - temp2;
            result.setText("" + temp3);
        }
    }

    public void mul(View view) {
        result.setText("");
        double temp1 = Double.parseDouble(a.getText().toString());
        double temp2 = Double.parseDouble(b.getText().toString());
        double temp3 = temp1 * temp2;
        if(a.getText().equals("") || b.getText().equals("")){
            result.setText("");
        }
        else {
            result.setText("" + temp3);
        }
    }

    public void div(View view) {
        result.setText("");
        double temp1 = Double.parseDouble(a.getText().toString());
        double temp2 = Double.parseDouble(b.getText().toString());
        double temp3 = temp1 / temp2;
        if(a.getText().equals("") || b.getText().equals("")){
            result.setText("");
        }
        else {
            result.setText("" + temp3);
        }
    }
}