Android：文字淡入淡出

我已经阅读了这个stackoverflow问题和答案，并尝试实现淡入淡出的文本：

如何让Android中的文字淡入淡出？

这是我的实现：

public class ShowActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_show); final TextView mSwitcher = (TextView) findViewById(R.id.textFade); mSwitcher.setText("old text"); final Animation in = new AlphaAnimation(0.0f, 1.0f); in.setDuration(5000); final Animation out = new AlphaAnimation(1.0f, 0.0f); out.setDuration(5000); out.setAnimationListener(new AnimationListener() { @Override public void onAnimationEnd(Animation animation) { mSwitcher.setText("New Text"); mSwitcher.startAnimation(in); } @Override public void onAnimationRepeat(Animation arg0) { // TODO Auto-generated method stub } @Override public void onAnimationStart(Animation arg0) { // TODO Auto-generated method stub } }); mSwitcher.startAnimation(out); mSwitcher.setText("Text 1."); mSwitcher.startAnimation(in); mSwitcher.startAnimation(out); mSwitcher.setText("Text 2."); mSwitcher.startAnimation(in); } } 

问题是，只显示文本2，它只会淡入而不淡出。 可能有什么不对？

Answer 1

问题是，每次开始淡出动画时，您都会立即开始淡入淡出动画。

我能够修改你的代码并得到一个简单的例子，这里是代码：

 import android.os.Handler; public class ShowActivity extends Activity { Handler handler; TextView mSwitcher; Animation in; Animation out; int fadeCount; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_show); fadeCount = 0; handler = new Handler(); mSwitcher = (TextView) findViewById(R.id.textView); mSwitcher.setText("old text"); in = new AlphaAnimation(0.0f, 1.0f); in.setDuration(5000); out = new AlphaAnimation(1.0f, 0.0f); out.setDuration(5000); out.setAnimationListener(new Animation.AnimationListener() { @Override public void onAnimationEnd(Animation animation) { fadeCount++; if (fadeCount == 3){ mSwitcher.setText(""); Intent i = new Intent(getApplication() , MainActivity.class); startActivity(i); } else { if (fadeCount == 1) { mSwitcher.setText("Text 2."); } else { mSwitcher.setText("New Text"); } mSwitcher.startAnimation(in); handler.postDelayed(mFadeOut, 5000); } } @Override public void onAnimationRepeat(Animation arg0) { // TODO Auto-generated method stub } @Override public void onAnimationStart(Animation arg0) { // TODO Auto-generated method stub } }); //mSwitcher.startAnimation(out); mSwitcher.setText("Text 1."); mSwitcher.startAnimation(in); /* mSwitcher.startAnimation(out); mSwitcher.setText("Text 2."); mSwitcher.startAnimation(in); */ handler.postDelayed(mFadeOut, 5000); } private Runnable mFadeOut =new Runnable(){ @Override public void run() { //Speed up the last fade-out so that the Activity opens faster if (fadeCount == 2){ out.setDuration(2000); } mSwitcher.startAnimation(out); } }; } 

Answer 2

看看我的课。 你只需要包括它。

 public class SuperTextView extends TextView { private boolean ready; public SuperTextView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); ready = false; addTextChangedListener(new CustomTextWatcher(this)); } public SuperTextView(Context context, AttributeSet attrs) { super(context, attrs); ready = false; addTextChangedListener(new CustomTextWatcher(this)); } public SuperTextView(Context context) { super(context); ready = false; addTextChangedListener(new CustomTextWatcher(this)); } @Override public void setText(CharSequence text, BufferType type) { if (ready && getText() != null && text != null) { String toChange = (String) text.toString(); String myText = "" + getText(); if (!myText.equals(toChange)) super.setText(text, type); } else super.setText(text, type); } public class CustomTextWatcher implements TextWatcher { private TextView element; private Integer[] rgb; public CustomTextWatcher(TextView element) { this.element = element; } @Override public void beforeTextChanged(CharSequence s, int start, int count, int after) { final int from = 255, to = 0; ValueAnimator anim = ValueAnimator.ofFloat(0, 1); anim.setDuration(500); rgb = parseColor(element.getCurrentTextColor()); final int[] alpha = new int[1]; anim.addUpdateListener(new ValueAnimator.AnimatorUpdateListener(){ @Override public void onAnimationUpdate(ValueAnimator animation) { alpha[0] = (int) (from + (to - from)*animation.getAnimatedFraction()); element.setTextColor(Color.argb(alpha[0], rgb[0], rgb[1], rgb[2])); } }); anim.start(); } @Override public void onTextChanged(CharSequence s, int start, int before, int count) { //Log.e("Text","change"); } @Override public void afterTextChanged(Editable s) { ready = true; final int from = 0, to = 255; ValueAnimator anim = ValueAnimator.ofFloat(0, 1); anim.setDuration(500); final int[] alpha = new int[1]; anim.addUpdateListener(new ValueAnimator.AnimatorUpdateListener(){ @Override public void onAnimationUpdate(ValueAnimator animation) { alpha[0] = (int) (from + (to - from)*animation.getAnimatedFraction()); element.setTextColor(Color.argb(alpha[0], rgb[0], rgb[1], rgb[2])); } }); anim.start(); } public Integer[] parseColor(int value) { Integer[] rgb = new Integer[3]; String hexColor = String.format("%06X", (0xFFFFFF & value)); int color = (int)Long.parseLong(hexColor, 16); rgb[0] = (color >> 16) & 0xFF; rgb[1] = (color >> 8) & 0xFF; rgb[2] = (color >> 0) & 0xFF; return rgb; } } } 

请注意，此类不能在ViewHolders管理的ListView项目中使用。