Cách tạo AlertDialog tùy chỉnh trong Android

Giới thiệu

Ví dụ này minh họa cách tạo AlertDialog tùy chỉnh (custom) với layout riêng trong Android.

Các bước thực hiện

Bước 1: Tạo dự án mới

Mở Android Studio, chọn File → New Project và điền thông tin cần thiết.

Bước 2: Thiết kế giao diện chính (res/layout/activity_main.xml)

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="https://schemas.android.com/apk/res/android"
    xmlns:tools="https://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="MainActivity">

    <TextView
        android:id="@+id/textView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_above="@+id/buttonShowCustomDialog"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="86dp"
        android:gravity="center"
        android:text="NHẤN ĐỂ XEM CUSTOM ALERT DIALOG"
        android:textSize="18sp"
        android:textStyle="bold" />

    <Button
        android:id="@+id/buttonShowCustomDialog"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="131dp"
        android:onClick="showDialog"
        android:text="Mở Dialog"
        android:textStyle="bold"
        style="@android:style/Widget.DeviceDefault.Button.Inset" />

</RelativeLayout>

Bước 3: Tạo layout custom dialog (res/layout/custom_dialog.xml)

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="https://schemas.android.com/apk/res/android"
    xmlns:app="https://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:padding="16dp">

    <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="16dp"
        android:text="Cảnh báo!"
        android:textSize="18sp"
        android:textStyle="bold" />

    <ImageView
        android:id="@+id/image"
        android:layout_width="60dp"
        android:layout_height="60dp"
        android:layout_below="@+id/text"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="16dp"
        app:srcCompat="@drawable/ic_warning" />

    <Button
        android:id="@+id/dialogButtonOK"
        android:layout_width="200dp"
        android:layout_height="wrap_content"
        android:layout_below="@+id/image"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="24dp"
        android:layout_marginBottom="16dp"
        android:paddingRight="5dp"
        android:text="Đóng"
        android:textSize="18sp"
        style="@style/Widget.AppCompat.Button.Colored" />

</RelativeLayout>

Bước 4: Viết code MainActivity.java

import android.app.Dialog;
import android.content.Context;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    private Button button;

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

        button = findViewById(R.id.buttonShowCustomDialog);
        button.setOnClickListener(v -> showCustomDialog());
    }

    private void showCustomDialog() {
        final Dialog dialog = new Dialog(this);
        dialog.setContentView(R.layout.custom_dialog);
        dialog.setCancelable(true);

        Button dialogButton = dialog.findViewById(R.id.dialogButtonOK);
        dialogButton.setOnClickListener(v -> {
            dialog.dismiss();
            Toast.makeText(this, "Đã đóng dialog", Toast.LENGTH_SHORT).show();
        });

        dialog.show();
    }
}

Cách dùng AlertDialog.Builder (khuyên dùng):

AlertDialog.Builder builder = new AlertDialog.Builder(this);
View dialogView = getLayoutInflater().inflate(R.layout.custom_dialog, null);
builder.setView(dialogView);

AlertDialog dialog = builder.create();
dialog.show();

Bước 5: Cấu hình AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="https://schemas.android.com/apk/res/android"
    package="app.com.sample">

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

    </application>
</manifest>

Chạy ứng dụng

Kết nối thiết bị, nhấn Run. Nhấn nút "Mở Dialog" để xem custom AlertDialog.