Android: Hiệu ứng Animation Alpha

Video hướng dẫn:

Bài viết hướng dẫn:

File activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">
    <ImageView
            android:layout_width="180dp"
            android:layout_height="180dp" app:srcCompat="@drawable/logov1study" android:id="@+id/imageViewLogo"
            app:layout_constraintTop_toTopOf="parent" app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent" app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintHorizontal_bias="0.497" app:layout_constraintVertical_bias="0.145"/>
    <Button
            android:text="Start Alpha"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:id="@+id/buttonStartAlpha"
            app:layout_constraintTop_toBottomOf="@+id/imageViewLogo"
            app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintVertical_bias="0.489"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintEnd_toEndOf="parent" android:textSize="24sp" android:textStyle="bold"
            android:textColor="#4CAF50"/>
</androidx.constraintlayout.widget.ConstraintLayout>

File resource anim_alpha.xml:

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
    <alpha android:fromAlpha="1"
           android:toAlpha="0"
           android:duration="3000"
           android:repeatMode="reverse"
           android:repeatCount="1"></alpha>
</set>

File MainActivity.java:

package v1study.com.animationalphav1study;

import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {
    ImageView imageViewLogo;
    Button buttonStartAlpha;
    Animation animation;

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

        getViews();

        buttonStartAlpha.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                animation=AnimationUtils.loadAnimation(getApplicationContext(),R.anim.anim_alpha);
                start(animation);
            }
        });
    }

    private void getViews() {
        imageViewLogo=findViewById(R.id.imageViewLogo);
        buttonStartAlpha=findViewById(R.id.buttonStartAlpha);
    }

    void start(Animation animation){
        imageViewLogo.startAnimation(animation);
    }
}