在java中对地图数据列表应用过滤器
我有一个在java中对地图数据列表应用过滤器,java,collections,filter,Java,Collections,Filter,我有一个列表数据,我想应用一些逻辑条件列表,这些逻辑条件按括号排序。 示例条件类似于((firstname=john和Lastname=11)或(工资=15000,地点=Mexico或(firstname=mathew和Lastname=13)) 我想在列表中运行这些条件,只返回匹配的数据 我写了下面的代码,如果有人可以修改工作的基础上的过滤器,这将是伟大的 package test; import java.util.List; import java.util.ArrayList; imp
列表
数据,我想应用一些逻辑条件列表,这些逻辑条件按括号排序。
示例条件类似于((firstname=john和Lastname=11)或(工资=15000,地点=Mexico或(firstname=mathew和Lastname=13))
我想在列表中运行这些条件
,只返回匹配的数据
我写了下面的代码,如果有人可以修改工作的基础上的过滤器,这将是伟大的
package test;
import java.util.List;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import java.util.stream.Collectors;
public class TestFilter {
public static void main(String argv[]) {
String[] firstnames = {"john", "david", "mathew", "john", "jerry", "Uffe", "Sekar", "Suresh", "Ramesh", "Raja"};
String[] secondnames = {"Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen", "Twenty"};
String[] salary = {"10000", "20000", "15000", "5323", "2000", "5346", "1000", "4889", "7854", "2438"};
String[] location = {"India", "Iceland", "Mexico", "Slovenia", "Poland", "Australia", "1000", "USA", "England", "Canada"};
List<Map<String, Object>> list = new ArrayList<>();
for (int i = 0; i < 10; i++) {
Map<String, Object> dataMap = new HashMap<>();
dataMap.put("firstname", firstnames[i]);
dataMap.put("secondname", secondnames[i]);
dataMap.put("salary", salary[i]);
dataMap.put("location", location[i]);
list.add(dataMap);
}
String filterRule = "((firstname = john AND Lastname = Eleven) OR (salary = 15000 AND location = Mexico OR (firstname = mathew AND lastname = Thirteen)))";
System.out.println(filter(list, filterRule));
}
public static List<Map<String, Object>> filter(List<Map<String, Object>> list, String filterRules) {
List<Map<String, Object>> filtered = list.stream()
.filter(p -> checkFilter(p, filterRules)).collect(Collectors.toList());
return filtered;
}
public static Boolean checkFilter(Map<String, Object> mapData, String filterRules) {
// Apply condition here and return true or false
// return (mapData.get("firstname") + "").equalsIgnoreCase("john");
//return true;
}
}
封装测试;
导入java.util.List;
导入java.util.ArrayList;
导入java.util.HashMap;
导入java.util.Map;
导入java.util.stream.collector;
公共类测试过滤器{
公共静态void main(字符串argv[]){
String[]firstnames={“john”、“david”、“mathew”、“john”、“jerry”、“Uffe”、“Sekar”、“Suresh”、“Ramesh”、“Raja”};
String[]secondnames={“十一”、“十二”、“十三”、“十四”、“十五”、“十六”、“十七”、“十八”、“十九”、“二十”};
字符串[]salary={“10000”、“20000”、“15000”、“5323”、“2000”、“5346”、“1000”、“4889”、“7854”、“2438”};
字符串[]位置={“印度”、“冰岛”、“墨西哥”、“斯洛文尼亚”、“波兰”、“澳大利亚”、“1000”、“美国”、“英国”、“加拿大”};
列表=新的ArrayList();
对于(int i=0;i<10;i++){
Map dataMap=newhashmap();
dataMap.put(“firstname”,firstname[i]);
dataMap.put(“secondname”,secondnames[i]);
dataMap.put(“工资”,工资[i]);
dataMap.put(“位置”,位置[i]);
列表。添加(数据映射);
}
String filterRule=“((firstname=john,Lastname=11)或(salary=15000,location=Mexico或(firstname=mathew,Lastname=13))”;
System.out.println(过滤器(列表,过滤器规则));
}
公共静态列表筛选器(列表、字符串筛选器规则){
List filtered=List.stream()
.filter(p->checkFilter(p,filterRules)).collect(collector.toList());
返回过滤;
}
公共静态布尔检查过滤器(映射映射数据、字符串过滤器规则){
//在此处应用条件并返回true或false
//return(mapData.get(“firstname”)+).equalsIgnoreCase(“john”);
//返回true;
}
}
我相信我的答案并不完全符合您的要求,但它可能会对您有所帮助,或者对如何过滤有新的想法。
我的想法是通过创建一个HashMap来模拟一个数据库,然后您可以根据某些条件进行过滤搜索,以及添加和删除这个数据库(HashMap)。。大概是这样的:
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
public class TestFilter {
public Map<Integer, ArrayList<String>> dataMap;
List<String> firstnames, lastnames, salarys, locations; // List is dynamic, you can add to it and delete at run time
public TestFilter(){
firstnames = new ArrayList<String>(Arrays.asList( new String[]{"john", "david", "mathew", "john", "jerry", "Uffe", "Sekar", "Suresh", "Ramesh", "Raja"}));
lastnames = new ArrayList<String>(Arrays.asList( new String[]{"Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen", "Twenty"}));
salarys = new ArrayList<String>(Arrays.asList( new String[]{"10000", "20000", "15000", "5323", "2000", "5346", "1000", "4889", "7854", "2438"}));
locations = new ArrayList<String>(Arrays.asList( new String[]{"India", "Iceland", "Mexico", "Slovenia", "Poland", "Australia", "1000", "USA", "England", "Canada"}));
populateDatabase();
}
public static void main(String argv[]) {
TestFilter tf = new TestFilter(); // just example to test
Scanner in = new Scanner(System.in);
System.out.println("Insert First Name");
String firstName = in.nextLine();
System.out.println("Insert Last Name");
String lastName = in.nextLine();
System.out.println("Insert Salary");
String salary = in.nextLine();
System.out.println("Insert Location");
String location = in.nextLine();
System.out.println("Filter Result: " + tf.filter(firstName, lastName, salary, location));
tf.addRecord("Yahya", "Almardeny", "3000", "Ireland"); //add new record
System.out.println("After Adding: " + tf.dataMap); // test it
tf.deleteRecord(new String[]{"Yahya", "Almardeny"}); // delete old record
System.out.println("After Deleting: " + tf.dataMap); // test it
}
//this method will return the record (as ArrayList) if there is a match or null if there is not.
public ArrayList<String> filter(String firstName, String lastName, String salary,String location) {
//attempt to filter
for(Integer id : dataMap.keySet()){ //cycle through the database to find a match according to the conditions
if (dataMap.get(id).contains(firstName) && dataMap.get(id).contains(lastName) ||
dataMap.get(id).contains(salary) && dataMap.get(id).contains(location)){
return new ArrayList<String>(Arrays.asList(new String[]{id.toString(), dataMap.get(id).get(0),
dataMap.get(id).get(1), dataMap.get(id).get(2), dataMap.get(id).get(3)}));
}
}
return null;
}
public void populateDatabase(){
dataMap = new HashMap<Integer, ArrayList<String>>(); // create HashMap as a database give every new record auto increment integer as an Id
for(int i=0; i<firstnames.size(); i++){
dataMap.put(i, new ArrayList<String>(Arrays.asList(new String[]
{firstnames.get(i), lastnames.get(i), salarys.get(i), locations.get(i)})));
}
}
public void addRecord(String firstName, String lastName, String salary,String location){
firstnames.add(firstName);
lastnames.add(lastName);
salarys.add(salary);
locations.add(location);
populateDatabase();
}
public void deleteRecord(Object obj){
int position = -1;
// delete by a combination of first and last names or salary and location
if(obj instanceof String[]){ // first index is first name, second is last name OR first index is the salary and the second is the location
for(Integer id : dataMap.keySet()){ //cycle through the database to find a match according to the conditions
if (dataMap.get(id).contains(((String[]) obj)[0]) && dataMap.get(id).contains(((String[]) obj)[1]) ||
dataMap.get(id).contains(((String[]) obj)[0]) && dataMap.get(id).contains(((String[]) obj)[1])){
position = id;
}
}
}
if(position>-1){
firstnames.remove(position);
lastnames.remove(position);
salarys.remove(position);
locations.remove(position);
populateDatabase();
}
}
}
如果您想支持动态规则。。。你必须研究一些规则引擎,比如Drools,或者至少一个规则表达式grammarI无法理解你想要实现什么!你想把什么样的东西还给你?ArrayList可以吗?您是否接受用户的输入来指定过滤器?@Yahya在函数中,
List
是返回值type@SarveshKumarSingh看起来很有希望,我会尝试一下,如果你有java的任何示例程序,请告诉我
Insert First Name
david
Insert Last Name
Twelve
Insert Salary
null
Insert Location
null
Filter Result: [1, david, Twelve, 20000, Iceland]
After Adding: {0=[john, Eleven, 10000, India], 1=[david, Twelve, 20000, Iceland], 2=[mathew, Thirteen, 15000, Mexico], 3=[john, Fourteen, 5323, Slovenia], 4=[jerry, Fifteen, 2000, Poland], 5=[Uffe, Sixteen, 5346, Australia], 6=[Sekar, Seventeen, 1000, 1000], 7=[Suresh, Eighteen, 4889, USA], 8=[Ramesh, Nineteen, 7854, England], 9=[Raja, Twenty, 2438, Canada], 10=[Yahya, Almardeny, 3000, Ireland]}
After Deleting: {0=[john, Eleven, 10000, India], 1=[david, Twelve, 20000, Iceland], 2=[mathew, Thirteen, 15000, Mexico], 3=[john, Fourteen, 5323, Slovenia], 4=[jerry, Fifteen, 2000, Poland], 5=[Uffe, Sixteen, 5346, Australia], 6=[Sekar, Seventeen, 1000, 1000], 7=[Suresh, Eighteen, 4889, USA], 8=[Ramesh, Nineteen, 7854, England], 9=[Raja, Twenty, 2438, Canada]}