<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"

    >

    <RelativeLayout

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_centerHorizontal="true"

        android:layout_centerVertical="true"

        >

        <EditText

            android:id="@+id/textUser_ID"

            android:layout_width="150dp"

            android:layout_height="wrap_content"

            android:maxLength="20"

            android:maxLines="1"

            android:layout_marginBottom="10dp"

            android:layout_marginRight="10dp"

            android:hint="아이디"

            />

        <EditText

            android:id="@+id/textPassword"

            android:inputType="textPassword"

            android:layout_width="150dp"

            android:layout_height="wrap_content"

            android:layout_below="@id/textUser_ID"

            android:maxLength="40"

            android:maxLines="1"

            android:hint="비밀번호"

            />

        <Button

            android:id="@+id/buttonLogin"

            android:layout_width="wrap_content"

            android:layout_height="100dp"

            android:layout_alignBaseline="@id/textUser_ID"

            android:layout_toRightOf="@id/textUser_ID"

            android:onClick="onButtonLoginClicked"

            android:text="로그인" />

    </RelativeLayout>

</RelativeLayout>

public class MainActivity extends AppCompatActivity {

    public static final int REQUEST_CODE_ANOTHER = 1001;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

    }

    public void onButtonLoginClicked(View v) {

        Intent intent = new Intent(getBaseContext(), MenuActivity.class);

        startActivityForResult(intent, REQUEST_CODE_ANOTHER);

    }

}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="match_parent"

android:layout_height="match_parent"

>

<RelativeLayout

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_centerHorizontal="true"

android:layout_centerVertical="true"

>

<Button

android:id="@+id/buttonCustomerMng"

android:layout_width="180dp"

android:layout_height="wrap_content"

android:text="고객 관리"

android:textSize="22dp"

android:layout_marginBottom="10dp"

android:onClick="onButtonCustomerMngClicked"

/>

<Button

android:id="@+id/buttonSalesMng"

android:layout_width="180dp"

android:layout_height="wrap_content"

android:text="매출 관리"

android:textSize="22dp"

android:layout_below="@id/buttonCustomerMng"

android:layout_marginBottom="10dp"

android:onClick="onButtonSalesMngClicked"

/>

<Button

android:id="@+id/buttonProductMng"

android:layout_width="180dp"

android:layout_height="wrap_content"

android:text="상품 관리"

android:textSize="22dp"

android:layout_below="@id/buttonSalesMng"

android:onClick="onButtonProductMngClicked"

/>

</RelativeLayout>

</RelativeLayout>

public class MenuActivity extends Activity {

    public static final int REQUEST_CODE_CUSTOMER_MNG = 2001;

    public static final int REQUEST_CODE_SALES_MNG = 2002;

    public static final int REQUEST_CODE_PRODUCT_MNG = 2003;

    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_menu);

    }

    public void onButtonCustomerMngClicked(View v) {

        Intent intent = new Intent(getBaseContext(), CustomerMngActivity.class);

        startActivityForResult(intent, REQUEST_CODE_CUSTOMER_MNG);

    }

    public void onButtonSalesMngClicked(View v) {

        Intent intent = new Intent(getBaseContext(), SalesMngActivity.class);

        startActivityForResult(intent, REQUEST_CODE_SALES_MNG);

    }

    public void onButtonProductMngClicked(View v) {

        Intent intent = new Intent(getBaseContext(), ProductMngActivity.class);

        startActivityForResult(intent, REQUEST_CODE_PRODUCT_MNG);

    }

    /**

     * 새로운 액티비티에서 돌아올 때 자동 호출되는 메소드

     */

    protected void onActivityResult(int requestCode, int resultCode, Intent intent) {

        super.onActivityResult(requestCode, resultCode, intent);

        if (requestCode == REQUEST_CODE_CUSTOMER_MNG || requestCode == REQUEST_CODE_SALES_MNG || requestCode == REQUEST_CODE_PRODUCT_MNG) {

            Toast toast = Toast.makeText(getBaseContext(), "요청코드 : " + requestCode + ", 결과코드 : " + resultCode, Toast.LENGTH_LONG);

            toast.show();

            if (resultCode == RESULT_OK) {

                String menu = intent.getExtras().getString("menu");

                toast = Toast.makeText(getBaseContext(), "응답으로 전달된 메뉴명 : " + menu, Toast.LENGTH_LONG);

                toast.show();

            }

        }

    }

}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="300dp"

android:layout_height="400dp" >

<Button

android:id="@+id/backButton"

android:layout_width="180dp"

android:layout_height="wrap_content"

android:layout_centerHorizontal="true"

android:layout_alignParentBottom="true"

android:layout_marginBottom="20dp"

android:text="닫기"

android:textSize="22dp"

/>

</RelativeLayout>

public class CustomerMngActivity extends Activity {

    Button backButton;

    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_customer_mng);

        backButton = (Button) findViewById(R.id.backButton);

        backButton.setOnClickListener(new OnClickListener() {

            public void onClick(View v) {

                Intent resultIntent = new Intent();

                resultIntent.putExtra("menu", "고객 관리");

                setResult(RESULT_OK, resultIntent);

                finish();

            }

        });

    }

}

public class SalesMngActivity extends Activity {

    Button backButton;

    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_sales_mng);

        backButton = (Button) findViewById(R.id.backButton);

        backButton.setOnClickListener(new OnClickListener() {

            public void onClick(View v) {

                Intent resultIntent = new Intent();

                resultIntent.putExtra("menu", "매출 관리");

                setResult(RESULT_OK, resultIntent);

                finish();

            }

        });

    } 

}

public class ProductMngActivity extends Activity {

    Button backButton;

    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_product_mng);

        backButton = (Button) findViewById(R.id.backButton);

        backButton.setOnClickListener(new OnClickListener() {

            public void onClick(View v) {

                Intent resultIntent = new Intent();

                resultIntent.putExtra("menu", "상품 관리");

                setResult(RESULT_OK, resultIntent);

                finish();

            }

        });

    } 

}

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

package="net.dev.mission04">

<application

    android:allowBackup="true"

    android:icon="@mipmap/ic_launcher"

    android:label="@string/app_name"

    android:roundIcon="@mipmap/ic_launcher_round"

    android:supportsRtl="true"

    android:theme="@style/AppTheme">

    <activity android:name="net.dev.mission04.MainActivity">

        <intent-filter>

            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />

        </intent-filter>

    </activity>

    <activity android:name="net.dev.mission04.MenuActivity">

    </activity>

    <activity android:name="net.dev.mission04.CustomerMngActivity"

        android:label="고객 관리"

        android:theme="@android:style/Theme.Dialog"

        >

    </activity>

    <activity android:name="net.dev.mission04.SalesMngActivity"

        android:label="매출 관리"

        android:theme="@android:style/Theme.Dialog"

        >

    </activity>

    <activity android:name="net.dev.mission04.ProductMngActivity"

        android:label="상품 관리"

        android:theme="@android:style/Theme.Dialog"

        >

    </activity>

</application>

</manifest>