Conversion between Java List and JSON Author: Chuwen Time: 2020-10-26 Classification: Android , Java comment <trans data-src="# 使用谷歌 `Gson`:">#Use Google 'Gson':</trans> <trans data-src="```">```</trans> <trans data-src="//list转换为json">//Convert list to json</trans> <trans data-src="Gson gson = new Gson(); ">Gson gson = new Gson(); </trans> <trans data-src="List<Person> persons = new ArrayList<Person>(); ">List<Person> persons = new ArrayList<Person>(); </trans> <trans data-src="String str = gson.toJson(persons); ">String str = gson.toJson(persons); </trans> <trans data-src="```">```</trans> <trans data-src="```">```</trans> <trans data-src="//json转换为list">//Json to list</trans> <trans data-src="Gson gson = new Gson(); ">Gson gson = new Gson(); </trans> <trans data-src="List<Person> persons = gson.fromJson(str, new TypeToken<List<Person>>(){}.getType()); ">List<Person> persons = gson.fromJson(str, new TypeToken<List<Person>>(){}.getType()); </trans> <trans data-src="```">```</trans>
Java time (formatted time format) to day of the week Author: Chuwen Time: 2020-10-19 Classification: Java comment <trans data-src="> 学习过程中的笔记，可能有不严谨的地方">>The notes in the learning process may be imprecise</trans> <trans data-src="# Java 时间(格式化的时间格式) 转 星期几">#Java time (formatted time format) to day of the week</trans> <trans data-src="```">```</trans> <trans data-src="import java.text.">import java.text.</trans> <trans data-src="ParseException;">ParseException;</trans> <trans data-src="import java.text.">import java.text.</trans> <trans data-src="SimpleDateFormat;">SimpleDateFormat;</trans> <trans data-src="import java.util.">import java.util.</trans> <trans data-src="Locale;">Locale;</trans> <trans data-src="public class Test {">public class Test {</trans> <trans data-src="public static void main(String[] args) throws ParseException {">public static void main(String[] args) throws ParseException {</trans> <trans data-src="System.out.println(strToWeek("2020-10-19 15:11:20", null));">System.out.println(strToWeek("2020-10-19 15:11:20", null));</trans> <trans data-src="}">}</trans> <trans data-src="/**">/**</trans> <trans data-src="* 格式化的时间字符串 转 星期几">*Formatted time string converted to day of week</trans> <trans data-src="* @param date 例如 2020-10-19 15:46:32">*@ param date, for example, 2020-10-19 15:46:32</trans> <trans data-src="* @param format 与 date 参数对应的格式，yyyy-MM-dd HH:mm:ss">*@ param format is the format corresponding to the date parameter, yyyy MM dd HH: mm: ss</trans> <trans data-src="* @return">* @return</trans> <trans data-src="*/">*/</trans> <trans data-src="public static String strToWeek(String date, String format) {">public static String strToWeek(String date, String format) {</trans> <trans data-src="if (format == null || format.isEmpty()) {">if (format == null || format.isEmpty()) {</trans> <trans data-src="format = "yyyy-MM-dd HH:mm:ss";">format = "yyyy-MM-dd HH:mm:ss";</trans> <trans data-src="}">}</trans> <trans data-src="SimpleDateFormat simpleDateFormat = new SimpleDateFormat("E", Locale.CHINA);">SimpleDateFormat simpleDateFormat = new SimpleDateFormat("E", Locale.CHINA);</trans> <trans data-src="try {">try {</trans> <trans data-src="return simpleDateFormat.format(">return simpleDateFormat.format(</trans> <trans data-src="(new SimpleDateFormat(format)).parse(date)">(new SimpleDateFormat(format)).parse(date)</trans> <trans data-src=");">);</trans> <trans data-src="} catch (ParseException e) {">} catch (ParseException e) {</trans> <trans data-src="return "error";">return "error";</trans> <trans data-src="}">}</trans> <trans data-src="}">}</trans> <trans data-src="}">}</trans> <trans data-src="```">```</trans>
Notes on deleting elements from List Author: Chuwen Time: 2020-10-15 Classification: Java comment <trans data-src="# 有以下代码">#The following codes are available</trans> <trans data-src="> 个人理解，可能有错">>Personal understanding, may be wrong</trans> <trans data-src="`MiBean.java`">`MiBean.java`</trans> <trans data-src="```">```</trans> <trans data-src="public class MiBean {">public class MiBean {</trans> <trans data-src="private int id;">private int id;</trans> <trans data-src="private String name;">private String name;</trans> <trans data-src="public MiBean(int id, String name) {">public MiBean(int id, String name) {</trans> <trans data-src="this.id = id;">this.id = id;</trans> <trans data-src="this.name = name;">this.name = name;</trans> <trans data-src="}">}</trans> <trans data-src="public int getId() {">public int getId() {</trans> <trans data-src="return id;">return id;</trans> <trans data-src="}">}</trans> <trans data-src="public void setId(int id) {">public void setId(int id) {</trans> <trans data-src="this.id = id;">this.id = id;</trans> <trans data-src="}">}</trans> <trans data-src="public String getName() {">public String getName() {</trans> <trans data-src="return name;">return name;</trans> <trans data-src="}">}</trans> <trans data-src="public void setName(String name) {">public void setName(String name) {</trans> <trans data-src="this.name = name;">this.name = name;</trans> <trans data-src="}">}</trans> <trans data-src="}">}</trans> <trans data-src="```">```</trans> <trans data-src="```">```</trans> <trans data-src="List<MiBean> miBeanLists = new ArrayList<>();">List<MiBean> miBeanLists = new ArrayList<>();</trans> <trans data-src="miBeanLists.add(new MiBean(9, "小米 10"));">MiBeanLists. add (new MiBean (9, "Xiaomi 10"));</trans> <trans data-src="miBeanLists.add(new MiBean(8, "小米 10 Pro"));">MiBeanLists.add (new MiBean (8, "Xiaomi 10 Pro"));</trans> <trans data-src="miBeanLists.add(new MiBean(7, "小米 10 Ultra"));">MiBeanLists. add (new MiBean (7, "Xiaomi 10 Ultra"));</trans> <trans data-src="miBeanLists.add(new MiBean(12, "Redmi K30 Pro"));">miBeanLists.add(new MiBean(12, "Redmi K30 Pro"));</trans> <trans data-src="miBeanLists.add(new MiBean(11, "Redmi K30 5G"));">miBeanLists.add(new MiBean(11, "Redmi K30 5G"));</trans> <trans data-src="miBeanLists.add(new MiBean(10, "Redmi K30 4G"));">miBeanLists.add(new MiBean(10, "Redmi K30 4G"));</trans> <trans data-src="//我以为可以直接遍历，然后调用 remove 方法移除">//I think you can directly traverse, and then call the remove method to remove</trans> <trans data-src="for(int i=0; i<miBeanLists.size(); ">for(int i=0; i<miBeanLists.size(); </trans> <trans data-src="i++){">i++){</trans> <trans data-src="miBeanLists.remove(i);">miBeanLists.remove(i);</trans> <trans data-src="}">}</trans> <trans data-src="//结果它只能删除部分">//As a result, it can only delete parts</trans> <trans data-src="//究其原因，原来是当删除之后 i<miBeanLists.size() 会重新判断">//The reason is that after deletion, i<miBeanLists. size() will re judge</trans> <trans data-src="//因为我们之前删除了一个，所以在删除之后加一句 i--; ">//Since we deleted one before, we add an i -;</trans> <trans data-src="就可以全部删除了">You can delete all</trans> <trans data-src="//修改后的代码如下">//The modified code is as follows</trans> <trans data-src="for(int i=0; i<miBeanLists.size(); ">for(int i=0; i<miBeanLists.size(); </trans> <trans data-src="i++){">i++){</trans> <trans data-src="miBeanLists.remove(i);">miBeanLists.remove(i);</trans> <trans data-src="i--;">i--;</trans> <trans data-src="}">}</trans> <trans data-src="```">```</trans> <trans data-src="# 结论">#Conclusion</trans> <trans data-src="> 究其原因，原来是当删除之后 `i<miBeanLists.size()` 会重新判断">>The reason is that 'i<miBeanLists. size()' will be re judged after deletion</trans> <trans data-src="> 因为我们之前删除了一个，所以在删除之后加一句 i--; ">>Since we deleted one before, we add an i -;</trans> <trans data-src="就可以全部删除了">You can delete all</trans> <trans data-src="---">---</trans> <trans data-src="> 复制别人总结的">>Copy others' summary</trans> <trans data-src=">> 在代码中，删除元素后，需要把下标减一。">>>In the code, after deleting the element, you need to subtract the subscript by one.</trans> <trans data-src="这是因为在每次删除元素后，ArrayList会将后面部分的元素依次往上挪一个位置(就是copy)，所以，下一个需要访问的下标还是当前下标，所以必须得减一才能把所有元素都遍历完">This is because every time an element is deleted, ArrayList will move the following elements up one position in turn (that is, copy), so the next subscript to be accessed is still the current subscript, so you must subtract one to traverse all elements</trans>
Use GsonFormat to parse json in array form Author: Chuwen Time: 2020-10-12 Classification: Android , Java comment <trans data-src="> 记下笔记，以访忘记">>Take notes to forget</trans> <trans data-src="# 假设有以下数据">#Assume the following data</trans> <trans data-src="```">```</trans> <trans data-src="[{">[{</trans> <trans data-src=""CarId": 1,">"CarId": 1,</trans> <trans data-src=""Time": "2017-11-26 16:58:11",">"Time": "2017-11-26 16:58:11",</trans> <trans data-src=""Cost": 10">"Cost": 10</trans> <trans data-src="}, {">}, {</trans> <trans data-src=""CarId": 1,">"CarId": 1,</trans> <trans data-src=""Time": "2017-11-26 16:58:19",">"Time": "2017-11-26 16:58:19",</trans> <trans data-src=""Cost": 20">"Cost": 20</trans> <trans data-src="}, {">}, {</trans> <trans data-src=""CarId": 1,">"CarId": 1,</trans> <trans data-src=""Time": "2017-11-26 16:58:24",">"Time": "2017-11-26 16:58:24",</trans> <trans data-src=""Cost": 30">"Cost": 30</trans> <trans data-src="}, {">}, {</trans> <trans data-src=""CarId": 1,">"CarId": 1,</trans> <trans data-src=""Time": "2017-11-26 16:58:28",">"Time": "2017-11-26 16:58:28",</trans> <trans data-src=""Cost": 40">"Cost": 40</trans> <trans data-src="}]">}]</trans> <trans data-src="```">```</trans> <trans data-src="# 以下类">#The following classes</trans> <trans data-src="```">```</trans> <trans data-src="public class GetCarAccountRecord {">public class GetCarAccountRecord {</trans> <trans data-src="/**">/**</trans> <trans data-src="* CarId : 1">* CarId : 1</trans> <trans data-src="* Time : 2017-11-26 04:58:11">* Time : 2017-11-26 04:58:11</trans> <trans data-src="* Cost : 10">* Cost : 10</trans> <trans data-src="*/">*/</trans> <trans data-src="private int CarId;">private int CarId;</trans> <trans data-src="private String Time;">private String Time;</trans> <trans data-src="private int Cost;">private int Cost;</trans> <trans data-src="public int getCarId() {">public int getCarId() {</trans> <trans data-src="return CarId;">return CarId;</trans> <trans data-src="}">}</trans> <trans data-src="public void setCarId(int CarId) {">public void setCarId(int CarId) {</trans> <trans data-src="this.">this.</trans> <trans data-src="CarId = CarId;">CarId = CarId;</trans> <trans data-src="}">}</trans> <trans data-src="public String getTime() {">public String getTime() {</trans> <trans data-src="return Time;">return Time;</trans> <trans data-src="}">}</trans> <trans data-src="public void setTime(String Time) {">public void setTime(String Time) {</trans> <trans data-src="this.">this.</trans> <trans data-src="Time = Time;">Time = Time;</trans> <trans data-src="}">}</trans> <trans data-src="public int getCost() {">public int getCost() {</trans> <trans data-src="return Cost;">return Cost;</trans> <trans data-src="}">}</trans> <trans data-src="public void setCost(int Cost) {">public void setCost(int Cost) {</trans> <trans data-src="this.">this.</trans> <trans data-src="Cost = Cost;">Cost = Cost;</trans> <trans data-src="}">}</trans> <trans data-src="}">}</trans> <trans data-src="```">```</trans> <trans data-src="# 使用 Gson 解析，然后遍历输出">#Use Gson to parse, and then traverse the output</trans> <trans data-src="```">```</trans> <trans data-src="List<GetCarAccountRecord> list = new Gson().fromJson(jsonObject.optJSONArray("ROWS_DETAIL").toString(), new TypeToken<List<GetCarAccountRecord>>() {}.getType());">List<GetCarAccountRecord> list = new Gson().fromJson(jsonObject.optJSONArray("ROWS_DETAIL").toString(), new TypeToken<List<GetCarAccountRecord>>() {}.getType());</trans> <trans data-src="for (GetCarAccountRecord getCarAccountRecord : list) {">for (GetCarAccountRecord getCarAccountRecord : list) {</trans> <trans data-src="Log.i("小车编号：", String.valueOf(getCarAccountRecord.getCarId()));">Log. i ("Car No.:", String. valueOf (getCarAccountRecord. getCarId()));</trans> <trans data-src="Log.i("充值金额：", String.valueOf(getCarAccountRecord.getCost()));">Log. i ("Recharge amount:", String. valueOf (getCarAccountRecord. getCost()));</trans> <trans data-src="}">}</trans> <trans data-src="```">```</trans>
Java creates a sub thread to start execution immediately Author: Chuwen Time: 2019-11-23 Classification: Java comment <trans data-src="```java">```java</trans> <trans data-src="public class InvokeRun extends Thread {">public class InvokeRun extends Thread {</trans> <trans data-src="private int i;">private int i;</trans> <trans data-src="@Override">@Override</trans> <trans data-src="public void run() {">public void run() {</trans> <trans data-src="for(; i<100; i++){">for(; i<100; i++){</trans> <trans data-src="System.out.println("["+Thread.currentThread().getName()+"]\t"+i);">System.out.println("["+Thread.currentThread().getName()+"]\t"+i);</trans> <trans data-src="}">}</trans> <trans data-src="}">}</trans> <trans data-src="public static void main(String[] args) throws Exception{">public static void main(String[] args) throws Exception{</trans> <trans data-src="for(int i=0; i<100; i++){">for(int i=0; i<100; i++){</trans> <trans data-src="System.out.println(Thread.currentThread().getName()+"\t"+i);">System.out.println(Thread.currentThread().getName()+"\t"+i);</trans> <trans data-src="if(i == 20){">if(i == 20){</trans> <trans data-src="new InvokeRun().start();">new InvokeRun().start();</trans> <trans data-src="new InvokeRun().start();">new InvokeRun().start();</trans> <trans data-src="//让当前主线程休眠 1ms">//Let the current main thread sleep for 1ms</trans> <trans data-src="//它会去执行另一个就绪状态的线程">//It will execute another ready thread</trans> <trans data-src="//这样的话，子线程就可以立即开始执行">//In this way, the child thread can start execution immediately</trans> <trans data-src="Thread.sleep(1);">Thread.sleep(1);</trans> <trans data-src="}">}</trans> <trans data-src="}">}</trans> <trans data-src="}">}</trans> <trans data-src="}">}</trans> <trans data-src="```">```</trans>