Button Android Calculator

Continuation of Android Calculator
SEE PREVIOUS TOPIC: https://youtu.be/eWv1x-hIhHU

FOLLOW THE LAYOUT IN THE FIRST PART OF THE VIDEO

public class MainActivity extends Activity {

EditText display;
Button num1;
Button num2;
Button add;
Button equal;
Button clear;

String temp1;
String temp2;

//FOR THE DEMO WE USE INT;
int Answer;

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

temp1="";
temp2="";


display = (EditText) findViewById(R.id.editTextDisplay);

//Para sa Num1 na Button Kapag na Click
num1=(Button) findViewById(R.id.button1);
num1.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View v) {
// Let's display the Value 1 to the EditText object
temp1=temp1 + 1;
display.setText(temp1);
//To set the focus out of the EditText object
display.setFocusable(false);
}
});

//For Num2 Button when Click
num2=(Button) findViewById(R.id.button2);
num2.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View v) {
// Let's display the Value 2 to the EditText object
temp1=temp1 + 2;
display.setText(temp1);

//To set the focus out of the EditText object
display.setFocusable(false);

}
});


add=(Button) findViewById(R.id.buttonaddition);
add.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//Add the number
temp2=temp1;
temp1="";

}
});


//For Equal Button When Click
equal=(Button) findViewById(R.id.buttonEqual);
equal.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Answer=Integer.parseInt(temp1) + Integer.parseInt(temp2);
display.setText(Integer.toString(Answer));
}
});

//For Clear Button When Click
clear=(Button) findViewById(R.id.buttonClear);
clear.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
temp1="";
temp2="";
display.setText("");
}
});

}