Android UI--开源项目IndexableListView(字母索引），Android最新实习面试经验总结

android:layout_height=“fill_parent”

android:id="@+id/listview" />

Activity

package com.woozzu.android.indexablelistview;

import java.util.ArrayList;

import java.util.Collections;

import java.util.List;

import android.app.Activity;

import android.content.Context;

import android.os.Bundle;

import android.widget.ArrayAdapter;

import android.widget.SectionIndexer;

import com.woozzu.android.util.StringMatcher;

import com.woozzu.android.widget.IndexableListView;

public class IndexableListViewActivity extends Activity {

private ArrayList mItems;

private IndexableListView mListView;

/** Called when the activity is first created. */

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

// 初始化一些数据

mItems = new ArrayList();

mItems.add(“Diary of a Wimpy Kid 6: Cabin Fever”);

mItems.add(“Steve Jobs”);

mItems.add(“Inheritance (The Inheritance Cycle)”);

mItems.add(“11/22/63: A Novel”);

mItems.add(“The Hunger Games”);

mItems.add(“The LEGO Ideas Book”);

mItems.add(“Explosive Eighteen: A Stephanie Plum Novel”);

mItems.add(“Catching Fire (The Second Book of the Hunger Games)”);

mItems.add(“Elder Scrolls V: Skyrim: Prima Official Game Guide”);

mItems.add(“Death Comes to Pemberley”);

mItems.add(“Diary of a Wimpy Kid 6: Cabin Fever”);

mItems.add(“Steve Jobs”);

mItems.add(“Inheritance (The Inheritance Cycle)”);

mItems.add(“11/22/63: A Novel”);

mItems.add(“The Hunger Games”);

mItems.add(“The LEGO Ideas Book”);

mItems.add(“Explosive Eighteen: A Stephanie Plum Novel”);

mItems.add(“Catching Fire (The Second Book of the Hunger Games)”);

mItems.add(“Elder Scrolls V: Skyrim: Prima Official Game Guide”);

mItems.add(“做作”);

mItems.add(“wokao”);

Collections.sort(mItems); // 排序

ContentAdapter adapter = new ContentAdapter(this,

android.R.layout.simple_list_item_1, mItems);

mListView = (IndexableListView) findViewById(R.id.listview);

mListView.setAdapter(adapter);

mListView.setFastScrollEnabled(true); // 设置快速滑动

}

private class ContentAdapter extends ArrayAdapter implements

SectionIndexer {

private String mSections = “#ABCDEFGHIJKLMNOPQRSTUVWXYZ”;

public ContentAdapter(Context context, int textViewResourceId,

List objects) {

super(context, textViewResourceId, objects);

}

@Override

public int getPositionForSection(int section) {

// If there is no item for current section, previous section will be

// selected

// 如果当前部分没有item，则之前的部分将被选择

for (int i = section; i >= 0; i–) {

for (int j = 0; j < getCount(); j++) {

System.out.println(getCount());

if (i == 0) { // #

// For numeric section 数字

for (int k = 0; k <= 9; k++) {// 1…9

// 字符串第一个字符与1~9之间的数字进行匹配

if (StringMatcher.match(

String.valueOf(getItem(j).charAt(0)),

String.valueOf(k)))

return j;

}

} else { // A~Z

if (StringMatcher.match(

String.valueOf(getItem(j).charAt(0)),

String.valueOf(mSections.charAt(i))))

return j;

}

}

}

return 0;

}

@Override

public int getSectionForPosition(int position) {

return 0;

}

@Override

public Object[] getSections() {

String[] sections = new String[mSections.length()];

for (int i = 0; i < mSections.length(); i++)

sections[i] = String.valueOf(mSections.charAt(i));

return sections;

}

}

}

字符串匹配工具类

/*

• Copyright 2011 woozzu

• Licensed under the Apache License, Version 2.0 (the “License”);

• you may not use this file except in compliance with the License.

• You may obtain a copy of the License at

• http://www.apache.org/licenses/LICENSE-2.0
  

• Unless required by applicable law or agreed to in writing, software

• distributed under the License is distributed on an “AS IS” BASIS,

• WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

• See the License for the specific language governing permissions and

• limitations under the License.

*/

package com.wwj.indexableListView.util;

public class StringMatcher {

// 这些变量是韩文，小巫也不知道是什么意思，有谁懂的马上联系我啊

private final static char KOREAN_UNICODE_START = ‘가’; // 韩文字符编码开始？

private final static char KOREAN_UNICODE_END = ‘힣’; // 韩文字符编码结束？

private final static char KOREAN_UNIT = ‘까’ - ‘가’; // 不知道是啥？

// 韩文的一些字符初始化

private final static char[] KOREAN_INITIAL = { ‘ㄱ’, ‘ㄲ’, ‘ㄴ’, ‘ㄷ’, ‘ㄸ’,

‘ㄹ’, ‘ㅁ’, ‘ㅂ’, ‘ㅃ’, ‘ㅅ’, ‘ㅆ’, ‘ㅇ’, ‘ㅈ’, ‘ㅉ’, ‘ㅊ’, ‘ㅋ’, ‘ㅌ’, ‘ㅍ’,

‘ㅎ’ };

/**

• 字符匹配

• @param value 需要keyword匹配的字符串

• @param keyword #ABCDEFGHIJKLMNOPQRSTUVWXYZ中的一个

• @return

*/

public static boolean match(String value, String keyword) {

if (value == null || keyword == null)

return false;

if (keyword.length() > value.length())

return false;

int i = 0, j = 0;

do {

// 如果是韩文字符并且在韩文初始数组里面

if (isKorean(value.charAt(i)) && isInitialSound(keyword.charAt(j))) {

if (keyword.charAt(j) == getInitialSound(value.charAt(i))) {

i++;

j++;

} else if (j > 0)

break;

else

i++;

} else {

// 逐个字符匹配

if (keyword.charAt(j) == value.charAt(i)) {

i++;

j++;

} else if (j > 0)

break;

else

i++;

}

} while (i < value.length() && j < keyword.length());

// 如果最后j等于keyword的长度说明匹配成功

return (j == keyword.length()) ? true : false;

}

// 判断字符是否在韩文字符编码范围内

private static boolean isKorean(char c) {

if (c >= KOREAN_UNICODE_START && c <= KOREAN_UNICODE_END)

return true;

return false;

}

// 判断是否在韩文字符里面

private static boolean isInitialSound(char c) {

for (char i : KOREAN_INITIAL) {

if (c == i)

return true;

}

return false;

}

// 获得韩文初始化字符数组里面的一个字符

private static char getInitialSound(char c) {

return KOREAN_INITIAL[(c - KOREAN_UNICODE_START) / KOREAN_UNIT];

}

}

自定义索引列表

/*

• Copyright 2011 woozzu

• Licensed under the Apache License, Version 2.0 (the “License”);

• you may not use this file except in compliance with the License.

• You may obtain a copy of the License at

• http://www.apache.org/licenses/LICENSE-2.0
  

• Unless required by applicable law or agreed to in writing, software

• distributed under the License is distributed on an “AS IS” BASIS,

• WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

• See the License for the specific language governing permissions and

• limitations under the License.

*/

package com.wwj.indexableListView.widget;

import android.content.Context;

import android.graphics.Canvas;

import android.util.AttributeSet;

import android.view.GestureDetector;

import android.view.MotionEvent;

import android.widget.ListAdapter;

import android.widget.ListView;

/**

• 自定义索引列表

• @author by 佚名

*/

public class IndexableListView extends ListView {

private boolean mIsFastScrollEnabled = false;

private IndexScroller mScroller = null;

private GestureDetector mGestureDetector = null;

public IndexableListView(Context context) {

super(context);

}

public IndexableListView(Context context, AttributeSet attrs) {

super(context, attrs);

}

public IndexableListView(Context context, AttributeSet attrs, int defStyle) {

super(context, attrs, defStyle);

}

@Override

public boolean isFastScrollEnabled() {

return mIsFastScrollEnabled;

}

@Override

public void setFastScrollEnabled(boolean enabled) {

mIsFastScrollEnabled = enabled;

if (mIsFastScrollEnabled) {

if (mScroller == null)

mScroller = new IndexScroller(getContext(), this);

} else {

if (mScroller != null) {

mScroller.hide();

mScroller = null;

}

}

}

@Override

public void draw(Canvas canvas) {

super.draw(canvas);

// Overlay index bar

if (mScroller != null)

mScroller.draw(canvas);

}

@Override

public boolean onTouchEvent(MotionEvent ev) {

// Intercept ListView’s touch event

if (mScroller != null && mScroller.onTouchEvent(ev))

return true;

if (mGestureDetector == null) {

// 创建一个GestureDetector（手势探测器）

mGestureDetector = new GestureDetector(getContext(),

new GestureDetector.SimpleOnGestureListener() {

@Override

public boolean onFling(MotionEvent e1, MotionEvent e2,

float velocityX, float velocityY) {

// If fling happens, index bar shows

// 显示索引条

mScroller.show();

return super.onFling(e1, e2, velocityX, velocityY);

}

});

}

mGestureDetector.onTouchEvent(ev);

return super.onTouchEvent(ev);

}

@Override

public boolean onInterceptTouchEvent(MotionEvent ev) {

return true;

}

@Override

public void setAdapter(ListAdapter adapter) {

super.setAdapter(adapter);

if (mScroller != null)

mScroller.setAdapter(adapter);

}

@Override

protected void onSizeChanged(int w, int h, int oldw, int oldh) {

super.onSizeChanged(w, h, oldw, oldh);

if (mScroller != null)

mScroller.onSizeChanged(w, h, oldw, oldh);

}

}

索引条

/*

• Copyright 2011 woozzu

• Licensed under the Apache License, Version 2.0 (the “License”);

• you may not use this file except in compliance with the License.

• You may obtain a copy of the License at

• http://www.apache.org/licenses/LICENSE-2.0
  

• Unless required by applicable law or agreed to in writing, software

• distributed under the License is distributed on an “AS IS” BASIS,

• WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

• See the License for the specific language governing permissions and

• limitations under the License.

*/

package com.wwj.indexableListView.widget;

import android.content.Context;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.Paint;

import android.graphics.RectF;

import android.os.Handler;

import android.os.Message;

import android.os.SystemClock;

import android.view.MotionEvent;

import android.widget.Adapter;

import android.widget.ListView;

import android.widget.SectionIndexer;

/**

• 右侧的索引条

• @author by 佚名

*/

public class IndexScroller {

private float mIndexbarWidth; // 索引条宽度

private float mIndexbarMargin; // 索引条外边距

private float mPreviewPadding; //

private float mDensity; // 密度

private float mScaledDensity; // 缩放密度

private float mAlphaRate; // 透明度

private int mState = STATE_HIDDEN; // 状态

private int mListViewWidth; // ListView宽度

private int mListViewHeight; // ListView高度

private int mCurrentSection = -1; // 当前部分

private boolean mIsIndexing = false; // 是否正在索引

private ListView mListView = null;

private SectionIndexer mIndexer = null;

private String[] mSections = null;

private RectF mIndexbarRect;

// 4种状态（已隐藏、正在显示、已显示、正在隐藏）

private static final int STATE_HIDDEN = 0;

private static final int STATE_SHOWING = 1;

private static final int STATE_SHOWN = 2;

private static final int STATE_HIDING = 3;

public IndexScroller(Context context, ListView lv) {

mDensity = context.getResources().getDisplayMetrics().density;

mScaledDensity = context.getResources().getDisplayMetrics().scaledDensity;

总结

【Android 详细知识点思维脑图（技能树）】

其实Android开发的知识点就那么多，面试问来问去还是那么点东西。所以面试没有其他的诀窍，只看你对这些知识点准备的充分程度。so，出去面试时先看看自己复习到了哪个阶段就好。

虽然 Android 没有前几年火热了，已经过去了会四大组件就能找到高薪职位的时代了。这只能说明 Android 中级以下的岗位饱和了，现在高级工程师还是比较缺少的，很多高级职位给的薪资真的特别高（钱多也不一定能找到合适的），所以努力让自己成为高级工程师才是最重要的。

这里附上上述的面试题相关的几十套字节跳动，京东，小米，腾讯、头条、阿里、美团等公司19年的面试题。把技术点整理成了视频和PDF（实际上比预期多花了不少精力），包含知识脉络 + 诸多细节。

由于篇幅有限，这里以图片的形式给大家展示一小部分。

详细整理在GitHub：Android架构视频+BAT面试专题PDF+学习笔记​

y = context.getResources().getDisplayMetrics().density;

mScaledDensity = context.getResources().getDisplayMetrics().scaledDensity;

总结

【Android 详细知识点思维脑图（技能树）】

[外链图片转存中…(img-Lgq9b7lw-1644027192654)]

其实Android开发的知识点就那么多，面试问来问去还是那么点东西。所以面试没有其他的诀窍，只看你对这些知识点准备的充分程度。so，出去面试时先看看自己复习到了哪个阶段就好。

虽然 Android 没有前几年火热了，已经过去了会四大组件就能找到高薪职位的时代了。这只能说明 Android 中级以下的岗位饱和了，现在高级工程师还是比较缺少的，很多高级职位给的薪资真的特别高（钱多也不一定能找到合适的），所以努力让自己成为高级工程师才是最重要的。

这里附上上述的面试题相关的几十套字节跳动，京东，小米，腾讯、头条、阿里、美团等公司19年的面试题。把技术点整理成了视频和PDF（实际上比预期多花了不少精力），包含知识脉络 + 诸多细节。

由于篇幅有限，这里以图片的形式给大家展示一小部分。

[外链图片转存中…(img-IPZkIecC-1644027192655)]

详细整理在GitHub：Android架构视频+BAT面试专题PDF+学习笔记​

网上学习 Android的资料一大堆，但如果学到的知识不成体系，遇到问题时只是浅尝辄止，不再深入研究，那么很难做到真正的技术提升。希望这份系统化的技术体系对大家有一个方向参考。