searchEdittext.addTextChangedListener(new TextWatcher() {
  @Override
  public void onTextChanged(CharSequence cs, int arg1, int arg2, int arg3) {
    // When user change the text
    mAdapter.getFilter().filter(cs);
  }
  
  @Override
  public void beforeTextChanged(CharSequence cs, int arg1, int arg2, int arg3) {
    //
  }
  
  @Override
  public void afterTextChanged(Editable arg0) {
    //
  }
});

public class ArrayAdapter<T> extends BaseAdapter implements Filterable {
  /**
   * Contains the list of objects that represent the data of this ArrayAdapter.
   * The content of this list is referred to as "the array" in the documentation.
   */
  private List<T> mObjects;
  
  /**
   * Lock used to modify the content of {@link #mObjects}. Any write operation
   * performed on the array should be synchronized on this lock. This lock is also
   * used by the filter (see {@link #getFilter()} to make a synchronized copy of
   * the original array of data.
   */
  private final Object mLock = new Object();
  
  // A copy of the original mObjects array, initialized from and then used instead as soon as
  // the mFilter ArrayFilter is used. mObjects will then only contain the filtered values.
  private ArrayList<T> mOriginalValues;
  private ArrayFilter mFilter;
  
  ...
  
  public Filter getFilter() {
    if (mFilter == null) {
      mFilter = new ArrayFilter();
    }
    return mFilter;
  }

  /**
   * <p>An array filter constrains the content of the array adapter with
   * a prefix. Each item that does not start with the supplied prefix
   * is removed from the list.</p>
   */
  private class ArrayFilter extends Filter {
    @Override
    protected FilterResults performFiltering(CharSequence prefix) {
      FilterResults results = new FilterResults();

      if (mOriginalValues == null) {
        synchronized (mLock) {
          mOriginalValues = new ArrayList<T>(mObjects);
        }
      }

      if (prefix == null || prefix.length() == 0) {
        ArrayList<T> list;
        synchronized (mLock) {
          list = new ArrayList<T>(mOriginalValues);
        }
        results.values = list;
        results.count = list.size();
      } else {
        String prefixString = prefix.toString().toLowerCase();

        ArrayList<T> values;
        synchronized (mLock) {
          values = new ArrayList<T>(mOriginalValues);
        }

        final int count = values.size();
        final ArrayList<T> newValues = new ArrayList<T>();

        for (int i = 0; i < count; i++) {
          final T value = values.get(i);
          final String valueText = value.toString().toLowerCase();

          // First match against the whole, non-splitted value
          if (valueText.startsWith(prefixString)) {
            newValues.add(value);
          } else {
            final String[] words = valueText.split(" ");
            final int wordCount = words.length;

            // Start at index 0, in case valueText starts with space(s)
            for (int k = 0; k < wordCount; k++) {
              if (words[k].startsWith(prefixString)) {
                newValues.add(value);
                break;
              }
            }
          }
        }

        results.values = newValues;
        results.count = newValues.size();
      }

      return results;
    }

    @Override
    protected void publishResults(CharSequence constraint, FilterResults results) {
      //noinspection unchecked
      mObjects = (List<T>) results.values;
      if (results.count > 0) {
        notifyDataSetChanged();
      } else {
        notifyDataSetInvalidated();
      }
    }
  }
}

public class User {
  private int avatarResId;
  private String name;

  public User(int avatarResId, String name) {
    this.avatarResId = avatarResId;
    this.name = name;
  }

  public int getAvatarResId() {
    return avatarResId;
  }

  public void setAvatarResId(int avatarResId) {
    this.avatarResId = avatarResId;
  }

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }
}

/**
   * Contains the list of objects that represent the data of this Adapter.
   * Adapter數(shù)據(jù)源
   */
  private List<User> mDatas;

 //過(guò)濾相關(guān)
  /**
   * This lock is also used by the filter
   * (see {@link #getFilter()} to make a synchronized copy of
   * the original array of data.
   * 過(guò)濾器上的鎖可以同步復(fù)制原始數(shù)據(jù)。
   * 
   */
  private final Object mLock = new Object();

  // A copy of the original mObjects array, initialized from and then used instead as soon as
  // the mFilter ArrayFilter is used. mObjects will then only contain the filtered values.
  //對(duì)象數(shù)組的備份，當(dāng)調(diào)用ArrayFilter的時(shí)候初始化和使用。此時(shí)，對(duì)象數(shù)組只包含已經(jīng)過(guò)濾的數(shù)據(jù)。
  private ArrayList<User> mOriginalValues;
  private ArrayFilter mFilter;

 @Override
  public Filter getFilter() {
    if (mFilter == null) {
      mFilter = new ArrayFilter();
    }
    return mFilter;
  }

//執(zhí)行過(guò)濾的方法
 protected FilterResults performFiltering(CharSequence prefix);

//得到過(guò)濾結(jié)果
 protected void publishResults(CharSequence prefix, FilterResults results);

 /**
   * 過(guò)濾數(shù)據(jù)的類(lèi)
   */
  /**
   * <p>An array filter constrains the content of the array adapter with
   * a prefix. Each item that does not start with the supplied prefix
   * is removed from the list.</p>
   * <p/>
   * 一個(gè)帶有首字母約束的數(shù)組過(guò)濾器，每一項(xiàng)不是以該首字母開(kāi)頭的都會(huì)被移除該list。
   */
  private class ArrayFilter extends Filter {
    //執(zhí)行刷選
    @Override
    protected FilterResults performFiltering(CharSequence prefix) {
      FilterResults results = new FilterResults();//過(guò)濾的結(jié)果
      //原始數(shù)據(jù)備份為空時(shí)，上鎖，同步復(fù)制原始數(shù)據(jù)
      if (mOriginalValues == null) {
        synchronized (mLock) {
          mOriginalValues = new ArrayList<>(mDatas);
        }
      }
      //當(dāng)首字母為空時(shí)
      if (prefix == null || prefix.length() == 0) {
        ArrayList<User> list;
        synchronized (mLock) {//同步復(fù)制一個(gè)原始備份數(shù)據(jù)
          list = new ArrayList<>(mOriginalValues);
        }
        results.values = list;
        results.count = list.size();//此時(shí)返回的results就是原始的數(shù)據(jù)，不進(jìn)行過(guò)濾
      } else {
        String prefixString = prefix.toString().toLowerCase();//轉(zhuǎn)化為小寫(xiě)

        ArrayList<User> values;
        synchronized (mLock) {//同步復(fù)制一個(gè)原始備份數(shù)據(jù)
          values = new ArrayList<>(mOriginalValues);
        }
        final int count = values.size();
        final ArrayList<User> newValues = new ArrayList<>();

        for (int i = 0; i < count; i++) {
          final User value = values.get(i);//從List<User>中拿到User對(duì)象
//          final String valueText = value.toString().toLowerCase();
          final String valueText = value.getName().toString().toLowerCase();//User對(duì)象的name屬性作為過(guò)濾的參數(shù)
          // First match against the whole, non-splitted value
          if (valueText.startsWith(prefixString) || valueText.indexOf(prefixString.toString()) != -1) {//第一個(gè)字符是否匹配
            newValues.add(value);//將這個(gè)item加入到數(shù)組對(duì)象中
          } else {//處理首字符是空格
            final String[] words = valueText.split(" ");
            final int wordCount = words.length;

            // Start at index 0, in case valueText starts with space(s)
            for (int k = 0; k < wordCount; k++) {
              if (words[k].startsWith(prefixString)) {//一旦找到匹配的就break，跳出for循環(huán)
                newValues.add(value);
                break;
              }
            }
          }
        }
        results.values = newValues;//此時(shí)的results就是過(guò)濾后的List<User>數(shù)組
        results.count = newValues.size();
      }
      return results;
    }

    //刷選結(jié)果
    @Override
    protected void publishResults(CharSequence prefix, FilterResults results) {
      //noinspection unchecked
      mDatas = (List<User>) results.values;//此時(shí)，Adapter數(shù)據(jù)源就是過(guò)濾后的Results
      if (results.count > 0) {
        notifyDataSetChanged();//這個(gè)相當(dāng)于從mDatas中刪除了一些數(shù)據(jù)，只是數(shù)據(jù)的變化，故使用notifyDataSetChanged()
      } else {
        /**
         * 數(shù)據(jù)容器變化 ----> notifyDataSetInValidated

         容器中的數(shù)據(jù)變化 ----> notifyDataSetChanged
         */
        notifyDataSetInvalidated();//當(dāng)results.count<=0時(shí)，此時(shí)數(shù)據(jù)源就是重新new出來(lái)的，說(shuō)明原始的數(shù)據(jù)源已經(jīng)失效了
      }
    }
  }

//User對(duì)象的name屬性作為過(guò)濾的參數(shù)
 final String valueText = value.getName().toString().toLowerCase();

//首字符匹配
valueText.startsWith(prefixString)

//你輸入的關(guān)鍵字包含在了某個(gè)item中，位置不做考慮，即可以不是第一個(gè)字符 
valueText.indexOf(prefixString.toString()) != -1