属性动画-526互联

activity_main.xml

<?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"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/hv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity

package com.example.anim3;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import android.animation.ObjectAnimator;
import android.animation.ValueAnimator;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ValueAnimator valueAnimator = ValueAnimator.ofFloat(0f, 1f);
        valueAnimator.setDuration(2000);
        valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(@NonNull ValueAnimator valueAnimator) {
                float animatedValue = (float) valueAnimator.getAnimatedValue();
                Log.e("leo", "onAnimationUpdate: "+animatedValue );
            }
        });
        valueAnimator.start();
        TextView textView = findViewById(R.id.hv);
        ObjectAnimator objectAnimator = (ObjectAnimator) ObjectAnimator.ofFloat(textView,"alpha",0f,1f);
        objectAnimator.setDuration(4000);
        objectAnimator.start();
    }
}