java8新特性中stream接口 distinct,sorted,peek,limit,skip reverse() 的用法
实例:
/** * @param invoiceType 发票类型 * @param reimburseStatus 发票状态 * @param keyword 关键字 * @param startTime 开始时间 * @param endTime 结束时间 * @param selectLable 标签 * @param wtUid 委托人账号 * @return */ private Stream<InvoiceModel> getInvoiceModelStream(String invoiceType, String reimburseStatus, String keyword, String startTime, String endTime, String selectLable, String wtUid) { Stream<InvoiceModel> stream = null; if (UtilString.isNotEmpty(wtUid)) { stream = InvoiceCache.getCache().stream().filter(model -> wtUid.equals(model.getCreateUser())).filter(model -> model.getResultStatus().startsWith(InvoiceConstant.RESULT_STATUS_VALUE_SUCCESS) || model.getResultStatus().startsWith(InvoiceConstant.RESULT_STATUS_VALUE_SUCCESS_WX));//success or success_wx } else { stream = InvoiceCache.getCache().stream().filter(model -> getContext().getUID().equals(model.getCreateUser())).filter(model -> model.getResultStatus().startsWith(InvoiceConstant.RESULT_STATUS_VALUE_SUCCESS) || model.getResultStatus().startsWith(InvoiceConstant.RESULT_STATUS_VALUE_SUCCESS_WX)); } if (UtilString.isNotEmpty(invoiceType)) { stream = stream.filter(model -> invoiceType.equals(model.getTicketType())); } if (UtilString.isNotEmpty(reimburseStatus)) { stream = stream.filter(model -> reimburseStatus.equals(model.getReimburseStatus())); } if (UtilString.isNotEmpty(selectLable)) { stream = stream.filter(invoiceModel -> { if (InvoiceConstant.TICKET_TYPE_INVOICE.equals(invoiceModel.getTicketType())) { InvoiceTicketModel model = (InvoiceTicketModel) invoiceModel.getTicketModel(); if (model != null) { return model.getLableName() != null && model.getLableName().contains(selectLable); } } else if (InvoiceConstant.TICKET_TYPE_TRAIN.equals(invoiceModel.getTicketType())) { TrainTicketModel model = (TrainTicketModel) invoiceModel.getTicketModel(); if (model != null) { return model.getLableName() != null && model.getLableName().contains(selectLable); } } else if (InvoiceConstant.TICKET_TYPE_PLANE.equals(invoiceModel.getTicketType())) { AirTicketModel model = (AirTicketModel) invoiceModel.getTicketModel(); if (model != null) { return model.getLableName() != null && model.getLableName().contains(selectLable); } } else if (InvoiceConstant.TICKET_TYPE_MANUAL.equals(invoiceModel.getTicketType())) { OtherTicketModel model = (OtherTicketModel) invoiceModel.getTicketModel(); if (model != null) { return model.getLableName() != null && model.getLableName().contains(selectLable); } } return false; }); } if (UtilString.isNotEmpty(keyword)) { stream = stream.filter(invoiceModel -> { if (InvoiceConstant.TICKET_TYPE_INVOICE.equals(invoiceModel.getTicketType())) { InvoiceTicketModel model = (InvoiceTicketModel) invoiceModel.getTicketModel(); if (model != null) { return model.getSellerTaxName().contains(keyword) || model.getBuyerTaxName().contains(keyword)||model.getAmount().contains(keyword); } } else if (InvoiceConstant.TICKET_TYPE_TRAIN.equals(invoiceModel.getTicketType())) { TrainTicketModel model = (TrainTicketModel) invoiceModel.getTicketModel(); if (model != null) { return model.getName().contains(keyword) || model.getStartLocation().contains(keyword) || model.getEndLocation().contains(keyword) || model.getTrainNumber().contains(keyword)||model.getAmount().contains(keyword); } } else if (InvoiceConstant.TICKET_TYPE_PLANE.equals(invoiceModel.getTicketType())) { AirTicketModel model = (AirTicketModel) invoiceModel.getTicketModel(); if (model != null) { return model.getName().contains(keyword) || model.getStartLocation().contains(keyword) || model.getEndLocation().contains(keyword) || model.getFlightNumber().contains(keyword)||model.getAmount().contains(keyword); } } else if (InvoiceConstant.TICKET_TYPE_MANUAL.equals(invoiceModel.getTicketType())) { OtherTicketModel model = (OtherTicketModel) invoiceModel.getTicketModel(); if (model != null) { return model.getMemo() != null && model.getMemo().contains(keyword)||model.getAmount().contains(keyword); } } return false; }); } if (UtilString.isNotEmpty(startTime)) { Timestamp startTimeTS = UtilDate.parseTsFromDateTime(startTime); stream = stream.filter(invoiceModel -> { if (InvoiceConstant.TICKET_TYPE_INVOICE.equals(invoiceModel.getTicketType())) { InvoiceTicketModel model = (InvoiceTicketModel) invoiceModel.getTicketModel(); if (model != null) { return model.getBillingDate().compareTo(startTimeTS) >= 0; } } else if (InvoiceConstant.TICKET_TYPE_TRAIN.equals(invoiceModel.getTicketType())) { TrainTicketModel model = (TrainTicketModel) invoiceModel.getTicketModel(); if (model != null) { return model.getStartTime().compareTo(startTimeTS) >= 0 || model.getEndTime().compareTo(startTimeTS) >= 0; } } else if (InvoiceConstant.TICKET_TYPE_PLANE.equals(invoiceModel.getTicketType())) { AirTicketModel model = (AirTicketModel) invoiceModel.getTicketModel(); if (model != null) { return model.getStartTime().compareTo(startTimeTS) >= 0 || model.getEndTime().compareTo(startTimeTS) >= 0; } } else if (InvoiceConstant.TICKET_TYPE_MANUAL.equals(invoiceModel.getTicketType())) { OtherTicketModel model = (OtherTicketModel) invoiceModel.getTicketModel(); if (model != null && model.getBillingDate() != null) { return model.getBillingDate().compareTo(startTimeTS) >= 0; } } return false; }); } if (UtilString.isNotEmpty(endTime)) { Timestamp endTimeTS = UtilDate.parseTsFromDateTime(endTime); stream = stream.filter(invoiceModel -> { if (InvoiceConstant.TICKET_TYPE_INVOICE.equals(invoiceModel.getTicketType())) { InvoiceTicketModel model = (InvoiceTicketModel) invoiceModel.getTicketModel(); if (model != null) { return model.getBillingDate().compareTo(endTimeTS) <= 0; } } else if (InvoiceConstant.TICKET_TYPE_TRAIN.equals(invoiceModel.getTicketType())) { TrainTicketModel model = (TrainTicketModel) invoiceModel.getTicketModel(); if (model != null) { return model.getStartTime().compareTo(endTimeTS) <= 0 || model.getEndTime().compareTo(endTimeTS) <= 0; } } else if (InvoiceConstant.TICKET_TYPE_PLANE.equals(invoiceModel.getTicketType())) { AirTicketModel model = (AirTicketModel) invoiceModel.getTicketModel(); if (model != null) { return model.getStartTime().compareTo(endTimeTS) <= 0 || model.getEndTime().compareTo(endTimeTS) <= 0; } } else if (InvoiceConstant.TICKET_TYPE_MANUAL.equals(invoiceModel.getTicketType())) { OtherTicketModel model = (OtherTicketModel) invoiceModel.getTicketModel(); if (model != null) { return model.getBillingDate().compareTo(endTimeTS) <= 0; } } return false; }); } stream = stream.distinct().sorted(Comparator.comparing(InvoiceModel::getCreateTime).reversed()); return stream; }
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/** * 查询发票列表 * * @param skip 跳过的条数 * @param rowCount 此页查询的条数 * @param invoiceType 发票类型 * @param keyword 模糊搜索时的关键词 * @param startTime 发票时间的范围 - 开始 * @param endTime 发票时间的范围 - 结束 * @param selectLable 发票名称 * @param wtUid 委托人账号 * @return */ public String querySuccessInvoiceList(int skip, int rowCount, String invoiceType, String reimburseStatus, String keyword, String startTime, String endTime, String selectLable, String wtUid) { ResponseObject ro = ResponseObject.newOkResponse(); try { Stream<InvoiceModel> stream1 = getInvoiceModelStream(invoiceType, reimburseStatus, keyword, startTime, endTime, selectLable, wtUid); Stream<InvoiceModel> stream3 = getInvoiceModelStream(invoiceType, reimburseStatus, keyword, startTime, endTime, selectLable, wtUid); List<InvoiceModel> list = stream1.skip(skip).limit(rowCount).collect(Collectors.toList()); if (skip == 0) {//第一页需要查询总金额和总张数 final int[] count = { 0 }; double sum = stream3.mapToDouble(invoiceModel -> { if (InvoiceConstant.TICKET_TYPE_INVOICE.equals(invoiceModel.getTicketType())) { InvoiceTicketModel model = (InvoiceTicketModel) invoiceModel.getTicketModel(); if (model != null) { count[0]++; return Double.parseDouble(model.getAmount()); } } else if (InvoiceConstant.TICKET_TYPE_TRAIN.equals(invoiceModel.getTicketType())) { TrainTicketModel model = (TrainTicketModel) invoiceModel.getTicketModel(); if (model != null) { count[0]++; return Double.parseDouble(model.getAmount()); } } else if (InvoiceConstant.TICKET_TYPE_PLANE.equals(invoiceModel.getTicketType())) { AirTicketModel model = (AirTicketModel) invoiceModel.getTicketModel(); if (model != null) { count[0]++; return Double.parseDouble(model.getAmount()); } } else if (InvoiceConstant.TICKET_TYPE_MANUAL.equals(invoiceModel.getTicketType())) { OtherTicketModel model = (OtherTicketModel) invoiceModel.getTicketModel(); if (model != null) { count[0]++; return Double.parseDouble(model.getAmount()); } } return 0; }).sum(); ro.put("sum", String.format("%.2f", sum)); ro.put("count", count[0]); } JSONArray ja = getInvoiceJA(list); ro.put("list", ja); return ro.toString(); } catch (Exception e) { e.printStackTrace(); return ResponseObject.newErrResponse("查询出错").toString(); } }
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//去重复 Stream<T> distinct(); //排序 Stream<T> sorted(); //根据属性排序 Stream<T> sorted(Comparator<? super T> comparator); //对对象的进行操作 Stream<T> peek(Consumer<? super T> action); //截断--取先maxSize个对象 Stream<T> limit(long maxSize); //截断--忽略前N个对象 Stream<T> skip(long n); 下面,我们用一些案例,对这些操作,做一些综合的演示 package com.taihao; import java.util.ArrayList; import java.util.Arrays; import java.util.Comparator; import java.util.List; import java.util.stream.Stream; public class TestJava8 { public static List<Emp> list = new ArrayList<>(); static { list.add(new Emp("xiaoHong1", 20, 1000.0)); list.add(new Emp("xiaoHong2", 25, 2000.0)); list.add(new Emp("xiaoHong3", 30, 3000.0)); list.add(new Emp("xiaoHong4", 35, 4000.0)); list.add(new Emp("xiaoHong5", 38, 5000.0)); list.add(new Emp("xiaoHong6", 45, 9000.0)); list.add(new Emp("xiaoHong7", 55, 10000.0)); list.add(new Emp("xiaoHong8", 42, 15000.0)); } public static void println(Stream<Emp> stream) { stream.forEach(emp -> { System.out.println(String.format("名字:%s,年纪:%s,薪水:%s", emp.getName(), emp.getAge(), emp.getSalary())); }); } public static void main(String[] args) { // 对数组流,先过滤重复,在排序,再控制台输出 1,2,3 Arrays.asList(3, 1, 2, 1).stream().distinct().sorted().forEach(str -> { System.out.println(str); }); // 对list里的emp对象,取出薪水,并对薪水进行排序,然后输出薪水的内容,map操作,改变了Strenm的泛型对象 list.stream().map(emp -> emp.getSalary()).sorted().forEach(salary -> { System.out.println(salary); }); // 根据emp的属性name,进行排序 println(list.stream().sorted(Comparator.comparing(Emp::getName))); // 给年纪大于30岁的人,薪水提升1.5倍,并输出结果 Stream<Emp> stream = list.stream().filter(emp -> { return emp.getAge() > 30; }).peek(emp -> { emp.setSalary(emp.getSalary() * 1.5); }); println(stream); // 数字从1开始迭代(无限流),下一个数字,是上个数字+1,忽略前5个 ,并且只取10个数字 // 原本1-无限,忽略前5个,就是1-5数字,不要,从6开始,截取10个,就是6-15 Stream.iterate(1, x -> ++x).skip(5).limit(10).forEach(System.out::println); } public static class Emp { private String name; private Integer age; private Double salary; public Emp(String name, Integer age, Double salary) { super(); this.name = name; this.age = age; this.salary = salary; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } public Double getSalary() { return salary; } public void setSalary(Double salary) { this.salary = salary; } } }
reverse()
是python中列表的一个内置方法(也就是说,在字典,字符串或者元组中,是没有这个内置方法的),用于列表中数据的反转;
exp:
lista = [1, 2, 3, 4]
lista.reverse()
print(lista)
打印结果:
[4, 3, 2, 1]
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//去重复
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Stream<T> distinct();
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//排序
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Stream<T> sorted();
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//根据属性排序
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Stream<T> sorted(Comparator<? super T> comparator);
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//对对象的进行操作
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Stream<T> peek(Consumer<? super T> action);
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//截断--取先maxSize个对象
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Stream<T> limit(long maxSize);
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//截断--忽略前N个对象
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Stream<T> skip(long n);
下面,我们用一些案例,对这些操作,做一些综合的演示
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package com.taihao;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.Comparator;
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import java.util.List;
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import java.util.stream.Stream;
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public class TestJava8 {
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public static List<Emp> list = new ArrayList<>();
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static {
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list.add(new Emp("xiaoHong1", 20, 1000.0));
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list.add(new Emp("xiaoHong2", 25, 2000.0));
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list.add(new Emp("xiaoHong3", 30, 3000.0));
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list.add(new Emp("xiaoHong4", 35, 4000.0));
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list.add(new Emp("xiaoHong5", 38, 5000.0));
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list.add(new Emp("xiaoHong6", 45, 9000.0));
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list.add(new Emp("xiaoHong7", 55, 10000.0));
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list.add(new Emp("xiaoHong8", 42, 15000.0));
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}
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public static void println(Stream<Emp> stream) {
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stream.forEach(emp -> {
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System.out.println(String.format("名字:%s,年纪:%s,薪水:%s", emp.getName(), emp.getAge(), emp.getSalary()));
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});
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}
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public static void main(String[] args) {
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// 对数组流,先过滤重复,在排序,再控制台输出 1,2,3
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Arrays.asList(3, 1, 2, 1).stream().distinct().sorted().forEach(str -> {
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System.out.println(str);
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});
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// 对list里的emp对象,取出薪水,并对薪水进行排序,然后输出薪水的内容,map操作,改变了Strenm的泛型对象
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list.stream().map(emp -> emp.getSalary()).sorted().forEach(salary -> {
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System.out.println(salary);
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});
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// 根据emp的属性name,进行排序
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println(list.stream().sorted(Comparator.comparing(Emp::getName)));
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// 给年纪大于30岁的人,薪水提升1.5倍,并输出结果
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Stream<Emp> stream = list.stream().filter(emp -> {
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return emp.getAge() > 30;
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}).peek(emp -> {
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emp.setSalary(emp.getSalary() * 1.5);
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});
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println(stream);
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// 数字从1开始迭代(无限流),下一个数字,是上个数字+1,忽略前5个 ,并且只取10个数字
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// 原本1-无限,忽略前5个,就是1-5数字,不要,从6开始,截取10个,就是6-15
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Stream.iterate(1, x -> ++x).skip(5).limit(10).forEach(System.out::println);
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}
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public static class Emp {
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private String name;
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private Integer age;
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private Double salary;
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public Emp(String name, Integer age, Double salary) {
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super();
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this.name = name;
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this.age = age;
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this.salary = salary;
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}
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public String getName() {
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return name;
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}
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public void setName(String name) {
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this.name = name;
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}
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public Integer getAge() {
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return age;
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}
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public void setAge(Integer age) {
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this.age = age;
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}
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public Double getSalary() {
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return salary;
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}
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public void setSalary(Double salary) {
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this.salary = salary;
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}
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}
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}