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Jackson和Gson的区别

Jackson和Gson的区别

Jackson 和 Gson 都是库/API。 这两个库都使用 JSON 数据。 这些也用于将 JSON 数据序列化和反序列化为 Java 对象。 这两个库都是 Java 的完整库，提供 JSON 数据绑定支持并能够处理复杂的数据类型。 这些库提供对 Java 泛型的支持。
Jackson 和 Gson 都可以反序列化 JSON 数据，而无需对实体类进行任何更改。 为了在代码中使用 Jackson 和 Gson，我们需要在 pom.xml 文件中添加以下依赖项。

Gson依赖

<dependency>  
    <groupId>com.google.code.gson</groupId>  
    <artifactId>gson</artifactId>  
    <version>2.9.0</version>  
</dependency>

Jackson依赖

<dependency>  
    <groupId>com.fasterxml.jackson.core</groupId>  
    <artifactId>jackson-core</artifactId>  
    <version>2.13.2</version>  
</dependency>

下面来看看如何使用 Jackson 和 Gson 库来序列化和反序列化 JSON 数据。

Gson序列化

将 Java 对象序列化为 JSON 有两种方法，即简单序列化(使用 toJson() 方法)和自定义序列化(使用自定义序列化程序)。
在简单序列化中，我们使用 Gson 库的 toJson() 方法来序列化一个 Java 对象。通过以下方式使用 toJson() 方法：

String jsonString = new Gson().toJson(object);

下面举个例子来看看如何使用它来序列化特定的 Java 对象。

文件代码： GsonSerializationExample1.java

//import required classes and package if any    
import java.util.Scanner;  
import com.google.gson.Gson;  

//create class GsonSerializationExample1  
public class GsonSerializationExample1 {    

    //main() methods start    
    public static void main(String args[]) {    

        // create Scanner class object    
        Scanner sc= new Scanner(System.in);         

        College colg;    

        String name, university, street, state, city, rank;    

        System.out.println("Enter College Name:");    
        name = sc.nextLine();    

        System.out.println("Enter University Name:");    
        university = sc.nextLine();    

        System.out.println("Enter Street:");    
        street = sc.nextLine();    

        System.out.println("Enter City:");    
        city = sc.nextLine();  

        System.out.println("Enter State:");    
        state = sc.nextLine();  

        System.out.println("Enter College Rank:");    
        rank = sc.nextLine();    

        // set values to College  object by using constructor    
        colg = new College(name, university, new Address(street, state, city), rank);  

        // serialize College using Gson  
        String jsonString = new Gson().toJson(colg);  
        System.out.println(jsonString);    

        //close Scanner class object    
        sc.close();    

    }    
}  
//create class College  
class College {      

    //Creating properties of College class      
    public String name;        
    public String university;     
    public Address address;   
    public String rank;     

    // constructor    
    College(String name, String university, Address address, String rank){    
        this.name = name;    
        this.university = university;    
        this.address = address;    
        this.rank = rank;    
    }    

}  
//create class Address   
class Address {    
    public String street;  
    public String state;  
    public String city;  

    Address(String street, String state, String city){    
          this.street = street;  
          this.state = state;  
          this.city = city;  
    }           
}

但是，也可以使用自定义序列化程序来序列化 Java 对象。 通过使用自定义序列化程序，可以修改标准行为。 可以处理空值、使用带有 html 的输出格式化程序、添加新输出或从输出中排除属性。

创建序列化程序文件： CollegeGsonSerializer.java -

import java.lang.reflect.Type;  
import java.text.SimpleDateFormat;  
import java.util.Date;  
import java.util.List;  
import java.util.stream.Collectors;  

import com.google.gson.JsonElement;  
import com.google.gson.JsonObject;  
import com.google.gson.JsonSerializationContext;  
import com.google.gson.JsonSerializer;  

// create custom serializer for College class  
public class CollegeGsonSerializer implements JsonSerializer<College> {  

    // create an instance of SimpleDateFormat class  
    private SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy");  


    @Override  
    public JsonElement serialize(College colg, Type type, JsonSerializationContext context) {  

        // create an instance of JsonObject  
        JsonObject colgJsonObj = new JsonObject();  

        // use addProperty() method to add properties to JsonObject  
        colgJsonObj.addProperty("<strong>College Name</strong>", colg.getCollegeName());  

        colgJsonObj.addProperty("<strong>University Name</strong>", colg.getUniversityName());  

        colgJsonObj.addProperty("<strong>College Est.</strong>", colg.getEst() != null ? sdf.format(colg.getEst()) : null);  

        colgJsonObj.addProperty("<strong>College Address</strong> ", colg.getAddress().size() > 0 ?  convertAddress(colg.getAddress()) : null);  

        colgJsonObj.addProperty("College Rank", colg.getRank() != null ? colg.getRank() : null);  

        return colgJsonObj;  
    }  
    private String convertAddress(List<String> address) {  
        return address.stream()  
          .collect(Collectors.joining("-"));  
    }  
}  
//create class College  
class College {      

    //Creating properties of College class      
    public String name;        
    public String university;     
    public List<String> address;   
    public Date est;  
    public String rank;     

    // constructor    
    College(String name, String university, List<String> address, Date est, String rank){    
        this.name = name;    
        this.university = university;    
        this.address = address;   
        this.est = est;  
        this.rank = rank;    
    }    
    //Getter and Setters  
    public String getCollegeName() {    
        return name;    
    }    
    public String getUniversityName() {    
        return university;    
    }    
    public Date getEst() {    
        return est;    
    }    
    public List<String> getAddress() {    
        return address;    
    }    
    public String getRank() {    
        return rank;    
    }  
    @Override      
    public String toString() {      
        // TODO Auto-generated method stub      
        return ""College [College Name: "+ name + ", College University = " + university + ", College Est. = " + est + ", Address = "+address+", College Rank = "+rank+"]";      
    }    
}

现在，使用上面的序列化器来序列化 College 类，示例代码： GsonSerializationExample2.java

import java.text.ParseException;  
import java.text.SimpleDateFormat;  
import java.util.ArrayList;  
import java.util.List;  
//import required classes and package if any    
import java.util.Scanner;  
import com.google.gson.Gson;  
import com.google.gson.GsonBuilder;  
//create class GsonSerializationExample2 to serialize POJO using custom serializer  
public class GsonSerializationExample2 {    
    //main() methods start    
    public static void main(String args[]) {    
        // create Scanner class object    
        Scanner sc= new Scanner(System.in);         
        College colg;    
        String name, university, add1, add2, rank, est;    
        List<String> address = new ArrayList<String>();  
        System.out.println("Enter College Name:");    
        name = sc.nextLine();    
        System.out.println("Enter University Name:");    
        university = sc.nextLine();    
        System.out.println("Enter College Address:");    
        add1 = sc.nextLine();         
        System.out.println("Enter University Address:");    
        add2 = sc.nextLine();  

        System.out.println("Enter College Est. in dd-mm-yyy format: ");    
        est = sc.nextLine();  

        System.out.println("Enter College Rank:");    
        rank = sc.nextLine();    

        address.add(add1);  
        address.add(add2);  

        Gson gson = new GsonBuilder()  
                .setPrettyPrinting()  
                .excludeFieldsWithoutExposeAnnotation()  
                .serializeNulls()  
                .disableHtmlEscaping()  
                .registerTypeAdapter(College.class, new CollegeGsonSerializer())  
                .create();  

        // create an instance of SimpleDateFormat  
        SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy");  

        try {  
            colg = new College(name, university, address, sdf.parse(est), rank);  

            // convert college to JSON  
            String jsonString = gson.toJson(colg);  
            System.out.println("After serializing College using custom serializer: "+jsonString);  

        } catch (ParseException e) {  
            e.printStackTrace();  
        }  

        //close Scanner class object    
        sc.close();    

    }    
}

Jackson序列化

就像 Gson 一样，也可以通过两种方式使用 Jackson 将 Java 对象序列化为 JSON，即简单序列化(使用 writeValueAsString() 方法)和自定义序列化(使用自定义序列化程序)。
在简单序列化中，使用 Jackson 库的 writeValueAsString() 方法来序列化 Java 对象。通过以下方式使用 writeValueAsString() 方法：

ObjectMapper mapper = new ObjectMapper();  
String jsonString = mapper.writeValueAsString(Object);

下面举个例子来了解如何使用它来序列化特定的 Java 对象。示例代码： JacksonSerializationExample1.java

//import required classes and package if any    
import java.util.Scanner;  

import com.fasterxml.jackson.core.JsonProcessingException;  
import com.fasterxml.jackson.databind.ObjectMapper;  

//create class JacksonSerializationExample1  
public class JacksonSerializationExample1 {    

    //main() methods start    
    public static void main(String args[]) {    

        // create an instance of ObjectMapper class  
        ObjectMapper mapper = new ObjectMapper();  

        // create Scanner class object    
        Scanner sc= new Scanner(System.in);         

        College colg;    

        String name, university, street, state, city, rank;    

        System.out.println("Enter College Name:");    
        name = sc.nextLine();    

        System.out.println("Enter University Name:");    
        university = sc.nextLine();    

        System.out.println("Enter Street:");    
        street = sc.nextLine();    

        System.out.println("Enter City:");    
        city = sc.nextLine();  

        System.out.println("Enter State:");    
        state = sc.nextLine();  

        System.out.println("Enter College Rank:");    
        rank = sc.nextLine();    

        // set values to College  object by using constructor    
        colg = new College(name, university, new Address(street, state, city), rank);  

        String jsonString;  

        try {  

            // serialize College using Jackson  
            jsonString = mapper.writeValueAsString(colg);  
            System.out.println(jsonString);  

        } catch (JsonProcessingException e) {  
            // TODO Auto-generated catch block  
            e.printStackTrace();  
        }  



        //close Scanner class object    
        sc.close();    

    }    
}  
//create class College  
class College {      

    //Creating properties of College class      
    public String name;        
    public String university;     
    public Address address;   
    public String rank;     

    // constructor    
    College(String name, String university, Address address, String rank){    
        this.name = name;    
        this.university = university;    
        this.address = address;    
        this.rank = rank;    
    }    

}  
//create class Address   
class Address {    
    public String street;  
    public String state;  
    public String city;  

    Address(String street, String state, String city){    
          this.street = street;  
          this.state = state;  
          this.city = city;  
    }           
}

就像 Gson 自定义序列化一样，也可以通过简单地创建一个序列化器来执行 Jackson 自定义序列化。 College.java 创建一个自定义序列化程序，稍后使用 Jackson 进行序列化。
代码文件：CollegeJacksonSerializer.java

import java.io.IOException;  
import java.text.SimpleDateFormat;  
import java.util.Date;  
import java.util.List;  
import java.util.stream.Collectors;  

import com.fasterxml.jackson.core.JsonGenerator;  
import com.fasterxml.jackson.databind.SerializerProvider;  
import com.fasterxml.jackson.databind.ser.std.StdSerializer;  

// create custom serializer for College class  
public class CollegeJacksonSerializer extends StdSerializer<College> {  

    // create an instance of SimpleDateFormat class  
    private SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy");  

    public CollegeJacksonSerializer(Class t) {  
        super(t);  
    }  

    @Override  
    public void serialize(College colg, JsonGenerator gen, SerializerProvider provider) throws IOException {  
        gen.writeStartObject();  

        gen.writeStringField("College Name ", colg.getCollegeName());  
        gen.writeStringField("College University ", colg.getUniversityName());  
        gen.writeStringField("Address ", colg.getAddress().stream().collect(Collectors.joining("-")));  
        gen.writeObjectField("College Est. ", colg.getEst() != null ? sdf.format(colg.getEst()) : null);  
        gen.writeStringField("College Rank: ", colg.getRank());  

        gen.writeEndObject();  
    }  

}  
//create class College  
class College {      

    //Creating properties of College class      
    public String name;        
    public String university;     
    public List<String> address;   
    public Date est;  
    public String rank;     

    // constructor    
    College(String name, String university, List<String> address, Date est, String rank){    
        this.name = name;    
        this.university = university;    
        this.address = address;   
        this.est = est;  
        this.rank = rank;    
    }    
    //Getter and Setters  
    public String getCollegeName() {    
        return name;    
    }    
    public String getUniversityName() {    
        return university;    
    }    
    public Date getEst() {    
        return est;    
    }    
    public List<String> getAddress() {    
        return address;    
    }    
    public String getRank() {    
        return rank;    
    }  
    @Override      
    public String toString() {      
        // TODO Auto-generated method stub      
        return "\"College [College Name: "+ name + ", College University = " + university + ", College Est. = " + est + ", Address = "+address+", College Rank = "+rank+"]";      
    }    
}

下面使用上面的序列化器来序列化 College 类。文件： JacksonSerializationExample2.java -

import java.text.ParseException;  
import java.text.SimpleDateFormat;  
import java.util.ArrayList;  
import java.util.List;  
//import required classes and package if any    
import java.util.Scanner;  
import com.fasterxml.jackson.core.JsonProcessingException;  
import com.fasterxml.jackson.core.util.DefaultPrettyPrinter;  
import com.fasterxml.jackson.databind.ObjectMapper;  
import com.fasterxml.jackson.databind.module.SimpleModule;  
//create class JacksonSerializationExample2 to serialize POJO using the custom serializer  
public class JacksonSerializationExample2 {    

    //main() methods start    
    public static void main(String args[]) throws ParseException {    

        // create Scanner class object    
        Scanner sc= new Scanner(System.in);         

        College colg;    

        String name, university, add1, add2, rank, est;    

        List<String> address = new ArrayList<String>();  

        System.out.println("Enter College Name:");    
        name = sc.nextLine();    

        System.out.println("Enter University Name:");    
        university = sc.nextLine();    

        System.out.println("Enter College Address:");    
        add1 = sc.nextLine();    

        System.out.println("Enter University Address:");    
        add2 = sc.nextLine();  

        System.out.println("Enter College Est. in dd-mm-yyy format: ");    
        est = sc.nextLine();  

        System.out.println("Enter College Rank:");    
        rank = sc.nextLine();    

        address.add(add1);  
        address.add(add2);  


        // create an instance of SimpleDateFormat  
        SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy");  

        colg = new College(name, university, address, sdf.parse(est), rank);  

        SimpleModule module = new SimpleModule();  
        module.addSerializer(new CollegeJacksonSerializer(College.class));  
        ObjectMapper mapper = new ObjectMapper();  
        try {  

            String jsonResult = mapper  
                    .registerModule(module)  
                    .writer(new DefaultPrettyPrinter())  
                    .writeValueAsString(colg);  
            System.out.println(jsonResult);  

        } catch (JsonProcessingException e) {  
            // TODO Auto-generated catch block  
            e.printStackTrace();  
        }         


        //close Scanner class object    
        sc.close();    

    }    
}

Gson反序列化
反序列化是将 JSON 字符串转换为 Java 对象的另一个重要概念。在两个实体类中都实现了 toString() 方法来说明输出。还可以通过两种方式将 JSON 字符串反序列化为 Java 对象，即简单反序列化和自定义反序列化。
下面以一个简单反序列化的例子来了解如何将 JSON 字符串反序列化为 Java 对象。

文件： GsonDeserializationExample1.java -

import java.text.ParseException;  
import java.util.Date;  
import java.util.List;  
import com.google.gson.Gson;  
//create class GsonDeserializationExample1 to deserialize JSON string into POJO  
public class GsonDeserializationExample1 {    
    //main() methods start    
    public static void main(String args[]) throws ParseException {    

    String jsonString = "{\"name\":\"JavaDeveloper\",\"expReq\":2,\"valid\":\"05-04-2022\","  
            + "\"ctc\":700001,\"employees\":[{\"empName\":\"Nicholas\",\"empId\":\"12001\","  
            + "\"empAdd\":\"Noida\",\"empContact\":\"123456\"},{\"empName\":\"Brittany\","  
            + "\"empId\":\"1002\",\"empAdd\":\"Noida\",\"empContact\":\"123457\"}]}";  

    JobPosition position = new Gson().fromJson(jsonString, JobPosition.class);  
    System.out.println(position);  
    }    
}  
//create class JobPosition  
class JobPosition {      

    //Creating properties of College class      
    public String name;        
    public int expReq;     
    public String valid;  
    public int ctc;     
    public List<Employee> employees;   

    // constructor    
    JobPosition(String name, int expReq, List<Employee> employees, String valid, int ctc){    
        this.name = name;    
        this.expReq = expReq;    
        this.valid = valid;   
        this.ctc = ctc;  
        this.employees = employees;    
    }  
    @Override      
    public String toString() {      
        // TODO Auto-generated method stub      
        return "\"Job Position [Job Position: "+ name + ", Experience Required: " + expReq + ", Last Date To Apply: " + valid + ", CTC: "+ctc+", Employees Details "+employees+"]";      
    }    
}  
//create class Employee   
class Employee {    
    public String empName;  
    public String empId;  
    public String empAdd;  
    public String empContact;  

    Employee(String empName, String empId, String empAdd, String empContact){    
          this.empName = empName;  
          this.empId = empId;  
          this.empAdd = empAdd;  
          this.empContact = empContact;  
    }     
    @Override      
    public String toString() {      
        // TODO Auto-generated method stub      
        return "\"Employee [Employee Name: "+ empName + ", Employee Id: " + empId + ", Employee Address: " + empAdd + ", Employee Contact: "+empContact+"]";      
    }  
}

在自定义反序列化中，使用自定义反序列化器。它允许修改标准的解串器行为。使用反序列化器来反映 Last Date To Apply 的正确时区。
下面再举一个自定义反序列化的例子，将 JSON 字符串反序列化为 Java 对象。

JobPositionGsonDeserializer.java

import java.lang.reflect.Type;  
import java.text.ParseException;  
import java.text.SimpleDateFormat;  
import java.util.ArrayList;  
import com.google.gson.JsonArray;  
import com.google.gson.JsonDeserializationContext;  
import com.google.gson.JsonDeserializer;  
import com.google.gson.JsonElement;  
import com.google.gson.JsonObject;  
import com.google.gson.JsonParseException;  
public class JobPositionGsonDeserializer implements JsonDeserializer<JobPosition> {  
    // create an instance of the SimpleDateFormat  
    private SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy");  

    @Override  
    public JobPosition deserialize(JsonElement element, Type typeOfT, JsonDeserializationContext context)  
            throws JsonParseException {  

        // read element as JSON Object  
        JsonObject obj = element.getAsJsonObject();  

        JsonElement JobPositionName = obj.get("name");  
        JsonElement expRequired = obj.get("expReq");  
        JsonElement ctc = obj.get("ctc");  
        JsonElement dateToApply = obj.get("valid");  
        JsonArray employeesData = obj.getAsJsonArray("employees");  

        ArrayList<String> empList = new ArrayList<String>();  
        if (employeesData != null) {  
            for (int i = 0; i < employeesData.size(); i++) {  
                empList.add(employeesData.get(i).getAsString());  
            }  
        }  

        JobPosition pos;  
        try {  
            pos = new JobPosition(JobPositionName.getAsString(), expRequired.getAsInt(), empList, sdf.parse(dateToApply.getAsString()), ctc.getAsInt());  
            return pos;  

        } catch (ParseException e) {  
            // TODO Auto-generated catch block  
            e.printStackTrace();  
        }  
        return null;  
    }  
}  
GsonDeserializationExample2.java

import java.text.ParseException;  
import java.util.Date;  
import java.util.List;  

import com.google.gson.Gson;  
import com.google.gson.GsonBuilder;  

//create class GsonDeserializationExample2 to deserialize JSON string into POJO using custom deserializer  
public class GsonDeserializationExample2 {    

    //main() methods start    
    public static void main(String args[]) throws ParseException {    

    String jsonString = "{\"name\":\"JavaDeveloper\",\"expReq\":2,"  
            + "\"valid\":\"05-04-2022\",\"ctc\":700001,\"employees\":[\"Nicholas\",\"Brittany\",Sharon]}";  

    Gson gson = new GsonBuilder()  
            .registerTypeAdapter(JobPosition.class, new JobPositionGsonDeserializer())  
            .create();  

    JobPosition position = gson.fromJson(jsonString, JobPosition.class);  
    System.out.println(position);  

    }    
}  
//create class JobPosition  
class JobPosition {      
    //Creating properties of College class      
    public String name;        
    public int expReq;     
    public Date valid;  
    public int ctc;     
    public List<String> employees;      
    // constructor    
    JobPosition(String name, int expReq, List<String> employees, Date valid, int ctc){    
        this.name = name;    
        this.expReq = expReq;    
        this.valid = valid;   
        this.ctc = ctc;  
        this.employees = employees;    
    }  
    @Override      
    public String toString() {      
        // TODO Auto-generated method stub      
        return "\"Job Position [Job Position: "+ name + ", Experience Required: " + expReq + ", Last Date To Apply: " + valid + ", CTC: "+ctc+", Employees Details "+employees+"]";      
    }    
}

Jackson反序列化

就像 Gson 一样，可以通过两种方式对 JSON 字符串进行反序列化，即简单反序列化和自定义反序列化。下面举一个例子来了解如何使用 Jackson 反序列化带有/不带有反序列化器的 JSON 字符串。

JacksonDeserializationExample1.java -

import java.text.ParseException;  
import java.util.List;  
import com.fasterxml.jackson.core.JsonProcessingException;  
import com.fasterxml.jackson.databind.JsonMappingException;  
import com.fasterxml.jackson.databind.ObjectMapper;  
//create class JacksonDeserializationExample1 to deserialize JSON string into POJO  
public class JacksonDeserializationExample1 {    
    //main() methods start    
    public static void main(String args[]) throws ParseException {    
        String jsonString = "{\"name\":\"JavaDeveloper\",\"expReq\":2,"  
                + "\"valid\":\"05-04-2022\",\"ctc\":700000,\"employees\":[\"Brittany\",\"Nicholas\",\"Sharon\"]}";  
        // create an instance of ObjectMapper class  
        ObjectMapper mapper = new ObjectMapper();  
        // deserialize jsonString into POJO  
        try {  
            JobPosition position = mapper.readValue(jsonString, JobPosition.class);  
            System.out.println(position);  
        } catch (JsonMappingException e) {  
            e.printStackTrace();  
        } catch (JsonProcessingException e) {  
            e.printStackTrace();  
        }  

    }    
}  
//create class JobPosition  
class JobPosition {      

    //Creating properties of College class      
    public String name;        
    public int expReq;     
    public String valid;  
    public int ctc;     
    public List<String> employees;   

    // default constructor  
    JobPosition(){  
        this.name = null;  
        this.expReq = 0;  
        this.valid = null;  
        this.ctc = 0;  
        this.employees = null;  
    }  

    // constructor    
    JobPosition(String name, int expReq, List<String> employees, String valid, int ctc){    
        this.name = name;    
        this.expReq = expReq;    
        this.valid = valid;   
        this.ctc = ctc;  
        this.employees = employees;    
    }  
    @Override      
    public String toString() {      
        // TODO Auto-generated method stub      
        return "\"Job Position [Job Position: "+ name + ", Experience Required: " + expReq + ", Last Date To Apply: " + valid + ", CTC: "+ctc+", Employees Details "+employees+"]";      
    }    
}

文件： JacksonDeserializationExample2.java

import java.text.ParseException;  
import java.text.SimpleDateFormat;  
import java.util.Date;  
import java.util.List;  
import com.fasterxml.jackson.core.JsonProcessingException;  
import com.fasterxml.jackson.databind.JsonMappingException;  
import com.fasterxml.jackson.databind.ObjectMapper;  
//create class JacksonDeserializationExample2 to deserialize JSON string into POJO  
public class JacksonDeserializationExample2 {    
    //main() methods start    
    public static void main(String args[]) throws ParseException {   
        String jsonString = "{\"name\":\"JavaDeveloper\",\"expReq\":2,"  
                + "\"valid\":\"2022-09-21T12:00:00+01:00\",\"ctc\":700000,\"employees\":[\"Brittany\",\"Nicholas\",\"Sharon\"]}";  
        // create an instance of SimpleDateFormat class  
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");     
        // create an instance of ObjectMapper class  
        ObjectMapper mapper = new ObjectMapper();  
        // add date format to ObjectMapper class  
        mapper.setDateFormat(sdf);  
        // deserialize jsonString into POJO  
        try {  
            JobPosition position = mapper.readValue(jsonString, JobPosition.class);  
            System.out.println(position);  
        } catch (JsonMappingException e) {  
            e.printStackTrace();  
        } catch (JsonProcessingException e) {  
            e.printStackTrace();  
        }  

    }    
}  
//create class JobPosition  
class JobPosition {      
    //Creating properties of College class      
    public String name;        
    public int expReq;     
    public Date valid;  
    public int ctc;     
    public List<String> employees;   

    // default constructor  
    JobPosition(){  
        this.name = null;  
        this.expReq = 0;  
        this.valid = null;  
        this.ctc = 0;  
        this.employees = null;  
    }  

    // constructor    
    JobPosition(String name, int expReq, List<String> employees, Date valid, int ctc){    
        this.name = name;    
        this.expReq = expReq;    
        this.valid = valid;   
        this.ctc = ctc;  
        this.employees = employees;    
    }  
    @Override      
    public String toString() {      
        // TODO Auto-generated method stub      
        return "\"Job Position [Job Position: "+ name + ", Experience Required: " + expReq + ", Last Date To Apply: " + valid + ", CTC: "+ctc+", Employees Details "+employees+"]";      
    }    
}

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