动画导致垃圾回收器创建日志条目

Question

我使用的是每个选项卡都是视图的TabActivity。 我想在更改选项卡时创建滑动动画。 动画启动logcat的每次给出了一个GC项：

08-17 16:37:00.840: D/dalvikvm(2767): GC_CONCURRENT freed 1920K, 43% free 6852K/11975K, paused 12ms+14ms, total 72ms 
08-17 16:37:01.235: D/dalvikvm(2767): GC_CONCURRENT freed 1480K, 40% free 7215K/11975K, paused 2ms+3ms, total 46ms 
08-17 16:37:01.235: D/dalvikvm(2767): WAIT_FOR_CONCURRENT_GC blocked 18ms 
08-17 16:37:05.715: D/dalvikvm(2767): GC_CONCURRENT freed 2092K, 43% free 6882K/11975K, paused 12ms+28ms, total 104ms 
08-17 16:37:06.370: D/dalvikvm(2767): GC_CONCURRENT freed 779K, 34% free 7912K/11975K, paused 14ms+6ms, total 65ms 
08-17 16:37:09.825: D/dalvikvm(2767): GC_FOR_ALLOC freed 1464K, 47% free 6455K/11975K, paused 19ms, total 19ms 
08-17 16:37:09.865: D/dalvikvm(2767): GC_FOR_ALLOC freed 1K, 34% free 7988K/11975K, paused 19ms, total 19ms 
08-17 16:37:09.865: I/dalvikvm-heap(2767): Grow heap (frag case) to 16.811MB for 944656-byte allocation 
08-17 16:37:10.370: D/dalvikvm(2767): GC_CONCURRENT freed 1427K, 38% free 8706K/13959K, paused 2ms+5ms, total 41ms 

每当你点击一个选项卡上，有两个动画：一个是当前标签滑出，一个新选项卡上滑动

。

这些是Animation定义：

public Animation inFromRightAnimation() { 
    Animation inFromRight = new TranslateAnimation(
      Animation.RELATIVE_TO_PARENT, +1.0f, 
      Animation.RELATIVE_TO_PARENT, 0.0f, 
      Animation.RELATIVE_TO_PARENT, 0.0f, 
      Animation.RELATIVE_TO_PARENT, 0.0f); 
    inFromRight.setDuration(500); 
    return inFromRight; 
} 

public Animation outToLeftAnimation() { 
    Animation outtoLeft = new TranslateAnimation(
      Animation.RELATIVE_TO_PARENT, 0.0f, 
      Animation.RELATIVE_TO_PARENT, -1.0f, 
      Animation.RELATIVE_TO_PARENT, 0.0f, 
      Animation.RELATIVE_TO_PARENT, 0.0f); 
    outtoLeft.setDuration(500); 
    return outtoLeft; 
} 

编辑：这是在标签的改变的代码：（currentTab是私人int类部件）

public void onTabChanged(String tabId) { 
    if (!initializatorFinished) { 
     getTabHost().setCurrentTab(currentTab); 
     return; 
    } 
    tab1 = (LinearLayout) findViewById(R.id.tabHome); 
    tab2 = (LinearLayout) findViewById(R.id.tabChanges); 
    tab3 = (LinearLayout) findViewById(R.id.tabTests); 
    tab4 = (ScrollView) findViewById(R.id.tabSettings); 
    tab5 = (LinearLayout) findViewById(R.id.tabInfo); 
    int currentTab = GetCurrentTab(); 
    int newTab = Integer.parseInt(tabId); 
     if (currentTab == 1 || currentTab == 0) { 
      if (newTab == 2) { 
       tab1.setAnimation(outToLeftAnimation()); 
       tab2.setAnimation(inFromRightAnimation()); 
      } 
      else if (newTab == 4) { 
       tab1.setAnimation(outToLeftAnimation()); 
       tab4.setAnimation(inFromRightAnimation()); 
      } 
      else if (newTab == 5) { 
       tab1.setAnimation(outToLeftAnimation()); 
       tab5.setAnimation(inFromRightAnimation()); 
      } 
     } 
     else if (currentTab == 2) { 
      if (newTab == 1) { 
       tab2.setAnimation(outToLeftAnimation()); 
       tab1.setAnimation(inFromRightAnimation()); 
      } 
      else if (newTab == 4) { 
       tab2.setAnimation(outToLeftAnimation()); 
       tab4.setAnimation(inFromRightAnimation()); 
      } 
      else if (newTab == 5) { 
       tab2.setAnimation(outToLeftAnimation()); 
       tab5.setAnimation(inFromRightAnimation()); 
      } 
     } 
     else if (currentTab == 4) { 
      if (newTab == 1) { 
       tab4.setAnimation(outToLeftAnimation()); 
       tab1.setAnimation(inFromRightAnimation()); 
      } 
      else if (newTab == 2) { 
       tab4.setAnimation(outToLeftAnimation()); 
       tab2.setAnimation(inFromRightAnimation()); 
      } 
      else if (newTab == 5) { 
       tab4.setAnimation(outToLeftAnimation()); 
       tab5.setAnimation(inFromRightAnimation()); 
      } 
     } 
     else if (currentTab == 5) { 
      if (newTab == 1) { 
       tab5.setAnimation(outToLeftAnimation()); 
       tab1.setAnimation(inFromRightAnimation()); 
      } 
      else if (newTab == 2) { 
       tab5.setAnimation(outToLeftAnimation()); 
       tab2.setAnimation(inFromRightAnimation()); 
      } 
      else if (newTab == 4) { 
       tab5.setAnimation(outToLeftAnimation()); 
       tab4.setAnimation(inFromRightAnimation()); 
      } 
     } 
     else if (currentTab == 3) { 
      if (newTab == 1) { 
       tab3.setAnimation(outToLeftAnimation()); 
       tab1.setAnimation(inFromRightAnimation()); 
      } 
      else if (newTab == 2) { 
       tab3.setAnimation(outToLeftAnimation()); 
       tab2.setAnimation(inFromRightAnimation()); 
      } 
      else if (newTab == 4) { 
       tab3.setAnimation(outToLeftAnimation()); 
       tab4.setAnimation(inFromRightAnimation()); 
      } 
      else if (newTab == 5) { 
       tab3.setAnimation(outToLeftAnimation()); 
       tab5.setAnimation(inFromRightAnimation()); 
      } 
     }   
     SetCurrentTab(Integer.parseInt(tabId)); 
    } 
private void SetCurrentTab(int tab) { 
    this.currentTab = tab; 
} 

private int GetCurrentTab() { 
    return this.currentTab; 
} 

Answer 1

如果您试图避免多余的分配，您可以在onCreate中创建一次这些动画，然后再简单地引用它们，而不是每次都创建一个新的动画。

事情是这样的：

private Animation mInFromRight; 
private Animation mInFromLeft; 

public Animation inFromRightAnimation() { 
    return mInFromRight; 
} 

public Animation outToLeftAnimation() { 
    return mInFromLeft; 
} 

@Override 
protected void onCreate (Bundle savedInstanceState){ 
    super.onCreate(savedInstanceState); 
    mInFromRight = new TranslateAnimation(
     Animation.RELATIVE_TO_PARENT, +1.0f, 
     Animation.RELATIVE_TO_PARENT, 0.0f, 
     Animation.RELATIVE_TO_PARENT, 0.0f, 
     Animation.RELATIVE_TO_PARENT, 0.0f); 
    mInFromRight.setDuration(500); 

    mInFromLeft = new TranslateAnimation(
     Animation.RELATIVE_TO_PARENT, 0.0f, 
     Animation.RELATIVE_TO_PARENT, -1.0f, 
     Animation.RELATIVE_TO_PARENT, 0.0f, 
     Animation.RELATIVE_TO_PARENT, 0.0f); 
    mInFromLeft.setDuration(500); 

    //...other oncreate code 
} 

除此之外，如果你仍然得到GC当你调用动画这是你无法控制的。某处android框架正在分配作为动画过程一部分被破坏的对象。

GC是正常的，必要的和预计会发生的，但是你最好留意事情。大多数情况下，过度的GC是由于在框架之外发生了一些愚蠢的事情，例如不必要地在循环中分配新对象。但是框架也需要GC，在这种情况下，似乎是发生了什么事情。

Answer 2

您在logcat中看到的条目告诉JVM执行了GC。如果启用了GC verbose，将会打印此信息。这些是详细的消息，在Java中，您可以通过删除详细信息（不确定关于android）来禁用它们。

原因可能是您的动画吃掉了更多的内存，这迫使达尔维克执行GC。