這篇我們來實作MainActivity部分

activity_main.xml

layout部分我設計了兩個Button做跳轉頁面，分別為開始、設置，並使用Guideline作綁定元件位置

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#ab7557"
    tools:context=".main.MainActivity">

    <Button
        android:id="@+id/btn_start"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="@drawable/redbackground_blackline"
        android:gravity="center"
        android:text="開始"
        android:textColor="@color/white"
        android:textSize="30dp"
        android:textStyle="bold"
        app:backgroundTint="@null"
        app:layout_constraintBottom_toTopOf="@+id/guideline27"
        app:layout_constraintEnd_toStartOf="@+id/guideline25"
        app:layout_constraintStart_toStartOf="@+id/guideline24"
        app:layout_constraintTop_toTopOf="@+id/guideline26" />

    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/guideline24"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        app:layout_constraintGuide_percent="0.2" />

    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/guideline25"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        app:layout_constraintGuide_percent="0.8" />

    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/guideline62"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        app:layout_constraintGuide_percent="0.1" />

    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/guideline26"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        app:layout_constraintGuide_percent="0.3" />

    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/guideline27"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        app:layout_constraintGuide_percent="0.45" />

    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/guideline52"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        app:layout_constraintGuide_percent="0.65" />

    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/guideline53"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        app:layout_constraintGuide_percent="0.8" />

    <Button
        android:id="@+id/btn_set"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="@drawable/redbackground_blackline"
        android:gravity="center"
        android:text="設置"
        android:textColor="@color/white"
        android:textSize="30dp"
        android:textStyle="bold"
        app:backgroundTint="@null"
        app:layout_constraintBottom_toTopOf="@+id/guideline53"
        app:layout_constraintEnd_toStartOf="@+id/guideline25"
        app:layout_constraintStart_toStartOf="@+id/guideline24"
        app:layout_constraintTop_toTopOf="@+id/guideline52" />

    <TextView
        android:id="@+id/textView11"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="@color/black"
        android:gravity="center"
        android:text="Chess Game"
        android:textSize="30dp"
        android:textColor="@color/white"
        android:textStyle="bold"
        app:layout_constraintBottom_toTopOf="@+id/guideline62"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity

public class MainActivity extends AppCompatActivity {
    private Button btn_start,btn_set;
    private Intent intent;
    private ArrayList musicList = new ArrayList();
    private ArrayList colorList = new ArrayList();
    private DialogData dialogData = new DialogData(this);
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btn_start = findViewById(R.id.btn_start);
        btn_set = findViewById(R.id.btn_set);

        getLastPageData();

        btn_start.setOnClickListener(v -> {
            intent = new Intent(this, CreateJoinRoom.class);
            intent.putIntegerArrayListExtra("musicData",musicList);
            intent.putIntegerArrayListExtra("colorData",colorList);
            startActivity(intent);
        });
        btn_set.setOnClickListener(v -> {
            intent = new Intent(this, Setting.class);
            intent.putIntegerArrayListExtra("musicData",musicList);
            intent.putIntegerArrayListExtra("colorData",colorList);
            startActivity(intent);
            finish();
        });
    }
    public void getLastPageData(){
        musicList = getIntent().getIntegerArrayListExtra("musicData");
        colorList = getIntent().getIntegerArrayListExtra("colorData");
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            dialogData.showExitDialog("確定退出?","確定","取消");
        }
        return false;
    }
}

完成之後，我們可以到AndroidManifest中設置畫面鎖定為直向

<activity
            android:name=".main.MainActivity"
            android:exported="true"
            android:screenOrientation="portrait">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

這樣我們基本的主畫面就完成了