title: Android面试相关链接
date: 2020-04-10 18:08:32
tags: Android
categories: Android
######Blankj
RecyclerView性能优化
https://github.com/Blankj/AndroidOfferKiller/blob/master/android/RecyclerView%20%E6%80%A7%E8%83%BD%E4%BC%98%E5%8C%96.md
App启动过程(含Activity启动过程)
https://github.com/Blankj/AndroidOfferKiller/blob/master/android/App%20%E5%90%AF%E5%8A%A8%E8%BF%87%E7%A8%8B%EF%BC%88%E5%90%AB%20Activity%20%E5%90%AF%E5%8A%A8%E8%BF%87%E7%A8%8B%EF%BC%89.md
Handler相关
1.谈谈消息机制Handler作用?有哪些要素?流程是怎样的?
考点：
作用
四大要素
具体流程
参考答案：
Handler的作用主要是与UI线程进行通信和延迟任务执行
四大要素：Message、MessageQueue、Handler、Looper
MessageQueue负责消息的存储与管理，使用单链表实现，为了快速插入和删除，在其next()方法无限循环判断是否有新消息，有就返回并移除
Handler负责Message的发送和处理
Looper负责关联线程和分发消息，在该线程的MessageQueue中取Message，分发给Handler。
Looper在创建的时候会创建一个MessageQueue，调用loop()方法开始消息循环，然后不断调用MessageQueue的next()方法，有消息处理，没有就阻塞。
2.一个线程能否创建多个Handler，Handler跟Looper之间的对应关系？
对于一个线程来说，只能有一个Looper，创建Looper的时候创建一个MessageQueue，可以分发到多个Handler
—> 可以从Looper扩展到ThreadLocal
1.mCommonRecyclerView.addOnChildAttachStateChangeListener(this);
mCommonRecyclerView.addOnChildAttachStateChangeListener(this);
通过重写onChildViewAttachedToWindow与onChildViewDetachedFromWindow方法
version.gradle
1 | /** |
Define ListNode
1 | public class ListNode { |
TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.addTab(tabLayout.newTab().setText("Tab"));
/**
* The one-stop shop for setting up this {@link TabLayout} with a {@link ViewPager}.
*
* <p>This method will link the given ViewPager and this TabLayout together so that any
* changes in one are automatically reflected in the other. This includes adapter changes,
* scroll state changes, and clicks. The tabs displayed in this layout will be populated
* from the ViewPager adapter's page titles.</p>
*
* <p>After this method is called, you will not need this method again unless you want
* to change the linked ViewPager.</p>
*
* <p>If the given ViewPager is non-null, it needs to already have a
* {@link PagerAdapter} set.</p>
*
* @param viewPager The ViewPager to link, or {@code null} to clear any previous link.
*/
public void setupWithViewPager(@Nullable final ViewPager viewPager) {
if (mViewPager != null && mPageChangeListener != null) {
// If we've already been setup with a ViewPager, remove us from it
mViewPager.removeOnPageChangeListener(mPageChangeListener);
}
if (viewPager != null) {
final PagerAdapter adapter = viewPager.getAdapter();
if (adapter == null) {
throw new IllegalArgumentException("ViewPager does not have a PagerAdapter set");
}
mViewPager = viewPager;
// Add our custom OnPageChangeListener to the ViewPager
if (mPageChangeListener == null) {
mPageChangeListener = new TabLayoutOnPageChangeListener(this);
}
mPageChangeListener.reset();
viewPager.addOnPageChangeListener(mPageChangeListener);
// Now we'll add a tab selected listener to set ViewPager's current item
setOnTabSelectedListener(new ViewPagerOnTabSelectedListener(viewPager));
// Now we'll populate ourselves from the pager adapter
setPagerAdapter(adapter, true);
} else {
// We've been given a null ViewPager so we need to clear out the internal state,
// listeners and observers
mViewPager = null;
setOnTabSelectedListener(null);
setPagerAdapter(null, true);
}
}final finally finalize 区别及用法
final
1，final修饰的class，代表不可以继承扩展。
2、final的方法也是不可以重写的。
3、final修饰的变量是不可以修改的。这里所谓的不可修改对于基本类型来来，的确是不可以修改。而对于引用类型来说，只能说不能重新赋值。也就是不能改变引用地址。但是作为引用类型，它内部所包含的内容如果不是final则可以随意修改