add the order restriction

.idea/vcs.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$" vcs="Git" />
+  </component>
+</project>

app/src/main/java/me/jj97181818/ch05_foodmenueventhw/MainActivity.java

@@ -1,15 +1,12 @@
 package me.jj97181818.ch05_foodmenueventhw;
 
-import android.graphics.Color;
-import android.support.v7.app.AppCompatActivity;
 import android.os.Bundle;
+import android.support.v7.app.AppCompatActivity;
 import android.view.View;
 import android.widget.CheckBox;
 import android.widget.CompoundButton;
 import android.widget.TextView;
 
-import org.w3c.dom.Text;
-
 import java.util.ArrayList;
 
 public class MainActivity extends AppCompatActivity implements CompoundButton.OnCheckedChangeListener {
@@ -50,13 +47,34 @@ public class MainActivity extends AppCompatActivity implements CompoundButton.On
     public void  takeOrder(View v) {
         String msg = "";
 
-        for (CompoundButton chk:selected)
-            msg += "\n" + chk.getText();
+        if (selected.size() == 3) {
+            for (CompoundButton chk:selected)
+                msg += "\n" + chk.getText();
 
-        if(msg.length() > 0)
-            msg = "你點購的餐點是：" + msg;
-        else
+            msg = "你點購的餐點是：" + msg + "\n總共是 50 元。";
+        }
+        else if (selected.size() == 4) {
+            for (CompoundButton chk:selected)
+                msg += "\n" + chk.getText();
+
+            msg = "你點購的餐點是：" + msg + "\n總共是 60 元。";
+        }
+        else if (selected.size() == 0){
             msg = "請點餐！";
+        }
+        else if (selected.size() > 4) {
+            msg = "點餐不得點超過 4 樣。";
+        }
+        else {
+            msg = "點餐不得點少於 3 樣。";
+        }
+
+
+
+//        if(msg.length() > 0)
+//
+//        else
+//            msg = "請點餐！";
 
         ((TextView) findViewById(R.id.showOrder)).setText(msg);
     }

app/src/main/res/layout/activity_main.xml

@@ -79,7 +79,7 @@
         android:layout_marginEnd="8dp"
         android:layout_marginBottom="165dp"
         android:text="請點餐"
-        android:textSize="30sp"
+        android:textSize="20sp"
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"