계산기 참고용

package com.example.administrator.a8_15;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    Button Add, Subtract, Multiply, Divide;
    TextView FirstNum, SecondNum, Answer;
    String Num1, Num2;
    Float Result;



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

        Add = (Button) findViewById(R.id.Add1);
        Subtract = (Button) findViewById(R.id.Subtract1);
        Multiply = (Button) findViewById(R.id.Multiply1);
        Divide = (Button) findViewById(R.id.Divide1);

        FirstNum = (TextView) findViewById(R.id.FirstNum1);
        SecondNum = (TextView) findViewById(R.id.SecondNum1);
        Answer = (TextView) findViewById(R.id.Answer1);

        Answer.setText("숫자를 입력해라");


    }

    public void btnadd(View v) {

        Num1 = FirstNum.getText().toString();
        Num2 = SecondNum.getText().toString();

       /* Result = Float.parseFloat(Num1) + Float.parseFloat(Num2);        Answer.setText(Result.toString());*/
        if (Num1.isEmpty() != true && Num2.isEmpty() != true) {
            Result = Float.parseFloat(Num1) + Float.parseFloat(Num2);
            Answer.setText(Result.toString());
            Toast.makeText(getApplicationContext(), "Added", Toast.LENGTH_SHORT).show();
        } else {
            Answer.setText("숫자를 입력하십시오.");
            Toast.makeText(getApplicationContext(), "Not Added", Toast.LENGTH_SHORT).show();

        }
    }



    public void btnsub(View v) {
        Num1 = FirstNum.getText().toString();
        Num2 = SecondNum.getText().toString();

        if (Num1.isEmpty() != true && Num2.isEmpty() != true) {
            Result = Float.parseFloat(Num1) - Float.parseFloat(Num2);
            Answer.setText(Result.toString());
            Toast.makeText(getApplicationContext(), "Subtracted", Toast.LENGTH_SHORT).show();
        } else {
            Answer.setText("숫자를 입력하십시오.");
            Toast.makeText(getApplicationContext(), "Not Subtracted", Toast.LENGTH_SHORT).show();

        }
    }

    public void btnmul(View v) {
        Num1 = FirstNum.getText().toString();
        Num2 = SecondNum.getText().toString();

        if (Num1.isEmpty() != true && Num2.isEmpty() != true) {
            Result = Float.parseFloat(Num1) * Float.parseFloat(Num2);
            Answer.setText(Result.toString());
            Toast.makeText(getApplicationContext(), "Multiplied", Toast.LENGTH_SHORT).show();
        } else {
            Answer.setText("숫자를 입력하십시오.");
            Toast.makeText(getApplicationContext(), "Not Multiplied", Toast.LENGTH_SHORT).show();

        }
    }

    public void btndiv(View v) {
        Num1 = FirstNum.getText().toString();
        Num2 = SecondNum.getText().toString();

        if (Num1.isEmpty() != true && Num2.isEmpty() != true) {
            Result = Float.parseFloat(Num1) / Float.parseFloat(Num2);
            Answer.setText(Result.toString());
            Toast.makeText(getApplicationContext(), "Divided", Toast.LENGTH_SHORT).show();
        } else {
            Answer.setText("숫자를 입력하십시오.");
            Toast.makeText(getApplicationContext(), "Not Divided", Toast.LENGTH_SHORT).show();

        }

    }

    @Override    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will        // automatically handle clicks on the Home/Up button, so long        // as you specify a parent activity in AndroidManifest.xml.        int id = item.getItemId();

        //noinspection SimplifiableIfStatement        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">
   />/ android:id="@+id/">

    <TextView android:text="@string/hello_world" android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:id="@+id/textView2" />

    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="Insert numbers below"        android:id="@+id/textView"        android:layout_below="@+id/textView2"        android:layout_alignParentLeft="true"        android:layout_alignParentStart="true" />

    <EditText        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:id="@+id/FirstNum1"        android:layout_below="@+id/textView"        android:layout_alignParentLeft="true"        android:layout_alignParentStart="true" />

    <EditText        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:id="@+id/SecondNum1"        android:layout_below="@+id/FirstNum1"        android:layout_alignParentLeft="true"        android:layout_alignParentStart="true" />

    <Button        android:layout_width="200dp"        android:layout_height="wrap_content"        android:text="Add"        android:id="@+id/Add1"        android:layout_below="@+id/SecondNum1"        android:layout_alignParentLeft="true"        android:layout_alignParentStart="true"        android:onClick="btnadd" />

    <Button        android:layout_width="200dp"        android:layout_height="wrap_content"        android:text="Subtract"        android:id="@+id/Subtract1"        android:layout_below="@+id/Add1"        android:layout_alignParentLeft="true"        android:layout_alignParentStart="true"        android:onClick="btnsub" />

    <Button        android:layout_width="200dp"        android:layout_height="wrap_content"        android:text="Multiply"        android:id="@+id/Multiply1"        android:layout_below="@+id/Subtract1"        android:layout_alignParentLeft="true"        android:layout_alignParentStart="true"        android:onClick="btnmul" />

    <Button        android:layout_width="200dp"        android:layout_height="wrap_content"        android:text="Divide"        android:id="@+id/Divide1"        android:layout_below="@+id/Multiply1"        android:layout_alignParentLeft="true"        android:layout_alignParentStart="true"        android:onClick="btndiv" />

    <TextView        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:text="New Text"        android:id="@+id/Answer1"        android:layout_alignParentBottom="true"        android:layout_alignParentLeft="true"        android:layout_alignParentStart="true"        android:onClick="btnadd" />

    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="Answer:"        android:id="@+id/textView4"        android:layout_above="@+id/Answer1"        android:layout_alignParentLeft="true"        android:layout_alignParentStart="true" />

</RelativeLayout>