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/**
** 为KProperty0添加一个扩展函数addObserver()，用来监听当值发生变化的时候刷新observer代码块
**/

fun <T> KProperty0<T>.addObserver(observer: (T) -> Unit) {
    (getDelegate(this) as ObservableProperty<T>?)?.addObserver(observer)
}

private fun <T> getDelegate(kProperty: KProperty0<T>) : Any? {
    val owner = (kProperty as PropertyReference).owner

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Iterable提供了一个sumByDouble方法，但是对于BigDecimal类型的Iterable运算的结果实在是差强人意，看下面这段代码的运行结果：

var list = listOf<BigDecimal>(BigDecimal(10.21.toString()), BigDecimal(8.21.toString()), BigDecimal(12.21.toString()))
    var repaymentAmount = BigDecimal(list.sumByDouble { it.toDouble() })
//    var repaymentAmount = list.sumByBigDecimal { it }
    println("repaymentAmount == $repaymentAmount")

输出的是repaymentAmount == 30.63000000000000255795384873636066913604736328125

仿照sumByDouble方法扩展了一个新的方法sumByBigDecimal，做了部分修改，具体如下

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Image source

https://gyazo.com/eb5c5741b6a9a16c692170a41a49c858.png

Try resize it!

• ![](https://gyazo.com/eb5c5741b6a9a16c692170a41a49c858.png | width=100)

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1. mysql 报错：

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock'

使用brew install mysql 安装MySQL后，有时候会出现这个问题，是由于mysql的服务还没有启动。 需要执行mysql.server start 命令就可以了

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/**
 * https://pspdfkit.com/blog/2016/keyboard-handling-on-android/
 * 监听软键盘变化(针对full screen model)
 */
public class KeyBoardChangeListener implements ViewTreeObserver.OnGlobalLayoutListener {
    private static final String TAG = "KeyBoardChangeListener";
    // Threshold for minimal keyboard height.
    final int MIN_KEYBOARD_HEIGHT_PX = 150;
    private final Rect windowVisibleDisplayFrame = new Rect();
    // Top-level window decor view.

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import java.util.regex.Matcher; 
import java.util.regex.Pattern; 

public class HTMLSpirit{ 
    public static String delHTMLTag(String htmlStr){ 
         String regEx_script="<script[^>]*?>[\\s\\S]*?<\\/script>"; //定义script的正则表达式 
         String regEx_style="<style[^>]*?>[\\s\\S]*?<\\/style>"; //定义style的正则表达式 
         String regEx_html="<[^>]+>"; //定义HTML标签的正则表达式 
         
         Pattern p_script=Pattern.compile(regEx_script,Pattern.CASE_INSENSITIVE); 

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/*
 * Copyright 2017 Google Inc.
 *
 * 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

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/**
*最近在研究网络请求数据解析的问题，发现json数据被强制转换为map结构的时候，会出现int变成double的问题
*在stackoverflow上看到了一个这个How can I prevent gson from converting integers to doubles 的问题，采用了这个答案
*https://stackoverflow.com/a/36529534/5279354答案
*/

import com.google.gson.JsonArray;
import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;

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// BSD License (http://lemurproject.org/galago-license)
package org.lemurproject.galago.utility.json;

public class JSONUtil {
  public static String escape(String input) {
    StringBuilder output = new StringBuilder();

    for(int i=0; i<input.length(); i++) {
      char ch = input.charAt(i);
      int chx = (int) ch;

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/**
* 将一个json串拍平为纯粹的字符串，也就是说，将json串序列化为string的过程中保留双引号这样的，保留转义字符
*/
@Test
public void test2() {
        String str = "[{\"image\"=\"https://pic4.zhimg.com/v2-01d1919be61d42c9ff2e4b82e6e55f1b.jpg\",\"type\"=0, \"id\"=9540230,\"ga_prefix\"=072507, \"title\"=\"日本新推出的「减肥可乐」，喝了真能减肥吗\"}, " +
                "{\"image\"=\"https://pic2.zhimg.com/v2-9caa37a6eba40ce688f25d88dc1d747d.jpg\", \"type\"=0, \"id\"=9539691, \"ga_prefix\"=072507, \"title\"=\"为了演好崇祯皇帝朱由检，和金士杰对戏前我好几天没吃饭\"}, " +
                "{\"image\"=\"https://pic2.zhimg.com/v2-34d7bfd12dfc8e3e73ee1450eb8ede35.jpg\", \"type\"=0, \"id\"=9539642, \"ga_prefix\"=072511, \"title\"=\"安徽小岗村第一个包产到户，为什么现在还是那么穷？\"}, " +