import android.content.Intent;
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 implements View.OnClickListener {

    private EditText e1;
    private EditText e2;
    private TextView t1;
    Button addButton;
    Button minusButton;

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

    }

    private void initialize (){
        e1 = (EditText) findViewById(R.id.editText);
        e2 = (EditText) findViewById(R.id.editText2);
        t1 = (TextView) findViewById(R.id.textView);
        addButton = (Button) findViewById(R.id.button);
        minusButton = (Button) findViewById(R.id.button2);

        addButton.setOnClickListener(this);
        minusButton.setOnClickListener(this);

    }
    @Override
    public void onClick (View view) {
        String num1 = e1.getText().toString();
        String num2 = e2.getText().toString();

        switch (view.getId()){
            case R.id.button:
                int add = Integer.parseInt(num1) + Integer.parseInt(num2);
                t1.setText(String.valueOf("the sum is: "+add));
                break;
            case R.id.button2:
                int sub = Integer.parseInt(num1) - Integer.parseInt(num2);
                t1.setText(String.valueOf("the difference is: "+sub));
                break;
        }

    }

}