ValueAnimator属性动画

1 官方文档

This class provides a simple timing engine（计时器） for running animations which calculate animated values and set them on target objects.There is a single timing pulse that all animations use. It runs in a custom handler to ensure that property changes happen on the UI thread.By default, ValueAnimator uses non-linear time interpolation, via the AccelerateDecelerateInterpolator class, which accelerates into and decelerates out of an animation. This behavior can be changed by calling setInterpolator(TimeInterpolator).（这段话是说动画默认是非匀速的，可以加速播放动画也可以减速播放，需要使用setInterpolator方法）

2 使用方法

final ValueAnimator animator = ValueAnimator.ofInt(0, 50);        animator.setDuration(2000);        animator.addListener(new Animator.AnimatorListener() {            @Override            public void onAnimationStart(Animator animation) {            }            @Override            public void onAnimationEnd(Animator animation) {            //动画播放结束执行的操作            }            @Override            public void onAnimationCancel(Animator animation) {            }            @Override            public void onAnimationRepeat(Animator animation) {            }        });        animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {            @Override             public void onAnimationUpdate(ValueAnimator animation) {                Integer value = (Integer) animation.getAnimatedValue();                int top = value * 10;                int bottom = top + textView.getHeight();                //不停重新布局视图位置                setLayout(getRecyclerViewRect(top,bottom));            }         });        animator.start();

3 效果展示

4 完整代码

package com.demo1;import android.animation.Animator;import android.animation.ValueAnimator;import android.graphics.Rect;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.view.View;import android.widget.Button;import android.widget.TextView;public class MainActivity extends AppCompatActivity implements View.OnClickListener {    private Button btn_click;    private TextView textView;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        btn_click = (Button) findViewById(R.id.tv);        btn_click.setOnClickListener(this);        textView = (TextView) findViewById(R.id.tvext);        textView.setOnClickListener(this);    }    @Override    public void onClick(View v) {        switch (v.getId()){            case R.id.tv:                startAnimator();                break;        }    }    private void startAnimator() {        final ValueAnimator animator = ValueAnimator.ofInt(0, 50);        animator.setDuration(2000);        animator.addListener(new Animator.AnimatorListener() {            @Override            public void onAnimationStart(Animator animation) {            }            @Override            public void onAnimationEnd(Animator animation) {            }            @Override            public void onAnimationCancel(Animator animation) {            }            @Override            public void onAnimationRepeat(Animator animation) {            }        });        animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {            @Override             public void onAnimationUpdate(ValueAnimator animation) {                Integer value = (Integer) animation.getAnimatedValue();                int top = value * 10;                int bottom = top + textView.getHeight();                //重新布局视图位置                setLayout(getRecyclerViewRect(top,bottom));            }         });        animator.start();    }    public void setLayout (Rect rect) {        textView.layout(rect.left, rect.top, rect.right, rect.bottom);        textView.invalidate();    }    public Rect getRecyclerViewRect (int top, int bottom) {        return new Rect(textView.getLeft(), top, textView.getRight(), bottom);    }}