JSON with json.simple Library

Maven Dependency:

<dependency>
    <groupId>com.googlecode.json-simple</groupId>
    <artifactId>json-simple</artifactId>
    <version>1.1</version>
  </dependency>

Student Pojo:

package com.ram.json.simple.pojo;

import java.util.ArrayList;
import java.util.List;

public class Student {
   
    public String name;
    public String age;
    public List<String> list = new ArrayList<String>();
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getAge() {
        return age;
    }
    public void setAge(String age) {
        this.age = age;
    }
    public List<String> getList() {
        return list;
    }
    public void setList(List<String> list) {
        this.list = list;
    }
   
   

}


Convert Java To JSON:

package com.ram.json.simple;

import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.json.simple.JSONObject;

import com.ram.jackson.pojo.Student;

public class JavaToJson {

    @SuppressWarnings("unchecked")
    public static void main(String[] args) {

        Student student = new Student();
        student.setName("Ramakrishna");
        student.setAge("26");
        List<String> list = new ArrayList<String>();
        list.add("100");
        list.add("200");
        list.add("300");
        student.setList(list);
       
        JSONObject jsonObject = new JSONObject();

        jsonObject.put("Name", student.getName());
        jsonObject.put("Age", student.getAge());
        jsonObject.put("list", student.getList());
   
        try {
   
            FileWriter file = new FileWriter("/home/biton/ramakrishna/delete/json/student.json");
            file.write(jsonObject.toJSONString());
            file.flush();
            file.close();
   
        } catch (IOException e) {
            e.printStackTrace();
        }
   
        System.out.print(jsonObject);
   
      }
   
    }


Convert JSON To Java:

package com.ram.json.simple;

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.List;

import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;


public class JsonToJava {

    @SuppressWarnings("unchecked")
    public static void main(String[] args) {
       
        JSONParser parser = new JSONParser();
       
        try {
   
            Object object = parser.parse(new FileReader("/home/biton/ramakrishna/delete/json/student.json"));
   
            JSONObject jsonObject = (JSONObject) object;
           
            System.out.println(jsonObject);
   
            String name = (String) jsonObject.get("Name");
            System.out.println(name);
   
            String age = (String) jsonObject.get("Age");
            System.out.println(age);
           
            List<String> list = (List<String>) jsonObject.get("list");
            System.out.println(list);
   
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ParseException e) {
            e.printStackTrace();
        }
       
      }

}

JSON with gson Library

Maven Dependency:

<dependency>
    <groupId>com.google.code.gson</groupId>
    <artifactId>gson</artifactId>
    <version>1.7.1</version>
  </dependency>

Student Pojo:

package com.ram.gson.pojo;

import java.util.ArrayList;
import java.util.List;

public class Student {
   
    public String name;
    public String age;
    public List<String> list = new ArrayList<String>();
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getAge() {
        return age;
    }
    public void setAge(String age) {
        this.age = age;
    }
    public List<String> getList() {
        return list;
    }
    public void setList(List<String> list) {
        this.list = list;
    }   
}

Convert Java To JSON:

package com.ram.gson;

import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import com.google.gson.Gson;
import com.ram.jackson.pojo.Student;

public class JavaToJson {

    public static void main(String[] args) {

        Student student = new Student();
        student.setName("Ramakrishna");
        student.setAge("26");
        List<String> list = new ArrayList<String>();
        list.add("100");
        list.add("200");
        list.add("300");
        student.setList(list);
       
        Gson gson = new Gson();
   
        String json = gson.toJson(student);
   
        try {

            FileWriter writer = new FileWriter("/home/ramakrishna/delete/json/student.json");
            writer.write(json);
            writer.close();
   
        } catch (IOException e) {
            e.printStackTrace();
        }
   
        System.out.println(json);
      }
   
    }


Convert JSON To Java:

package com.ram.gson;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

import com.google.gson.Gson;
import com.ram.gson.pojo.Student;

public class JsonToJava {

    public static void main(String[] args) {
       
        Gson gson = new Gson();
       
        try {
   
            BufferedReader br = new BufferedReader(
                new FileReader("/home/ramakrishna/delete/json/student.json"));
   
            Student student = gson.fromJson(br, Student.class);
   
            System.out.println("Name:"+student.getName());
            System.out.println("Age:"+student.getAge());
            System.out.println("Values:"+student.getList());
   
        } catch (IOException e) {
            e.printStackTrace();
        }
       
      }

}

JSON with Jackson Library

Maven Dependency:

<!-- For Jackson -->
  <repositories>
    <repository>
        <id>codehaus</id>
        <url>http://repository.codehaus.org/org/codehaus</url>
    </repository>
  </repositories>

<dependency>
        <groupId>org.codehaus.jackson</groupId>
        <artifactId>jackson-mapper-asl</artifactId>
        <version>1.8.5</version>
</dependency>

Studen Pojo:

package com.ram.jackson.pojo;

import java.util.ArrayList;
import java.util.List;

public class Student {
   
    public String name;
    public String age;
    public List<String> list = new ArrayList<String>();
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getAge() {
        return age;
    }
    public void setAge(String age) {
        this.age = age;
    }
    public List<String> getList() {
        return list;
    }
    public void setList(List<String> list) {
        this.list = list;
    }
}
 

Convert Java To JSON:

package com.ram.jackson;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;

import com.ram.jackson.pojo.Student;

public class JavaToJson {

    public static void main(String[] args) {

        Student student = new Student();
        student.setName("Ramakrishna");
        student.setAge("26");
        List<String> list = new ArrayList<String>();
        list.add("100");
        list.add("200");
        list.add("300");
        student.setList(list);
       
        ObjectMapper mapper = new ObjectMapper();
   
        try {
   
            mapper.writeValue(new File("/home/ramakrishna/delete/json/student.json"), student);
   
            System.out.println(mapper.writeValueAsString(student));
   
        } catch (JsonGenerationException e) {
   
            e.printStackTrace();
   
        } catch (JsonMappingException e) {
   
            e.printStackTrace();
   
        } catch (IOException e) {
   
            e.printStackTrace();
   
        }
   
      }
   
    }

Convert JSON To Java:

package com.ram.jackson;

import java.io.File;
import java.io.IOException;

import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;

import com.ram.jackson.pojo.Student;

public class JsonToJava {

    public static void main(String[] args) {
       
        ObjectMapper mapper = new ObjectMapper();
       
        try {
   
            Student student = mapper.readValue(new File("/home/ramakrishna/delete/json/student.json"), Student.class);
   
            System.out.println("Name:"+student.getName());
            System.out.println("Age:"+student.getAge());
            System.out.println("Values:"+student.getList());
           
   
        } catch (JsonGenerationException e) {
   
            e.printStackTrace();
   
        } catch (JsonMappingException e) {
   
            e.printStackTrace();
   
        } catch (IOException e) {
   
            e.printStackTrace();
   
        }
   
      }
}

JSON Introduction

JSON Introduction

JSON (JavaScript Object Notation) is a lightweight data-interchange format.

Format of JSON is  Key with Value pair 

It is easy for humans to read and write. It is easy for machines to parse and generate.

JSON format is used for serializing & transmitting structured data over network connection.

Web Services and API'S use JSON format to provide public data.

 JSON is language independent like XML

Java libraries to process JSON data, which are Jackson, Google Gson and JSON.simple

Map Interface Examples

package com.ram;

import java.util.Collection;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Set;
import java.util.SortedMap;
import java.util.TreeMap;

/**
 *
 * @author ramakrishna.v
 *
 */
public class MapInterfaceExamples {
   
    public static void main(String args[]) {
       
        Map<String,String> hashMap = new HashMap<String,String>();
        hashMap.put("key1","R");
        hashMap.put("key2","A");
        hashMap.put("key3","M");
       
        //Getting all keys
        retrieveValues("Map","HashMap",hashMap.keySet());
        //Getting all values
        retrieveValues("Map","HashMap",hashMap.values());
        //Getting all values based on keys
        getValues("Map","HashMap",hashMap,hashMap.keySet());
        //Getting all values based on keys getting by set interface
        displayValues("Map","HashMap",hashMap,hashMap.entrySet());
         
        Map<String,String> treeMap1 = new TreeMap<String,String>();
        treeMap1.put("key1","R");
        treeMap1.put("key2","A");
        treeMap1.put("key3","M");
       
        //Getting all keys
        retrieveValues("Map","TreeMap",treeMap1.keySet());
        //Getting all values
        retrieveValues("Map","TreeMap",treeMap1.values());
        //Getting all values based on keys
        getValues("Map","TreeMap",treeMap1,treeMap1.keySet());
        //Getting all values based on keys getting by set interface
        displayValues("Map","TreeMap",treeMap1,treeMap1.entrySet());
       
        SortedMap<String,String> treeMap2 = new TreeMap<String,String>();
        treeMap2.put("key1","R");
        treeMap2.put("key2","A");
        treeMap2.put("key3","M");
       
        //Getting all keys
        retrieveValues("SortedMap","TreeMap",treeMap2.keySet());
        //Getting all values
        retrieveValues("SortedMap","TreeMap",treeMap2.values());
        //Getting all values based on keys
        getValues("Map","TreeMap",treeMap2,treeMap2.keySet());
        //Getting all values based on keys getting by set interface
        displayValues("Map","TreeMap",treeMap2,treeMap2.entrySet());
         
        Map<String,String> linkedHashMap = new LinkedHashMap<String,String>();
        linkedHashMap.put("key1","R");
        linkedHashMap.put("key2","A");
        linkedHashMap.put("key3","M");
       
        //Getting all keys
        retrieveValues("Map","LinkedHashMap",linkedHashMap.keySet());
        //Getting all values
        retrieveValues("Map","LinkedHashMap",linkedHashMap.values());
        //Getting all values based on keys
        getValues("Map","LinkedHashMap",linkedHashMap,linkedHashMap.keySet());
        //Getting all values based on keys getting by set interface
        displayValues("Map","LinkedHashMap",linkedHashMap,linkedHashMap.entrySet());
       
        Map<String,String> hashtable = new Hashtable<String,String>();
        hashtable.put("key1","R");
        hashtable.put("key2","A");
        hashtable.put("key3","M");
       
        //Getting all keys
        retrieveValues("Map","LinkedHashMap",hashtable.keySet());
        //Getting all values
        retrieveValues("Map","LinkedHashMap",hashtable.values());
        //Getting all values based on keys
        getValues("Map","hashtable",hashtable,hashtable.keySet());
        //Getting all values based on keys getting by set interface
        displayValues("Map","hashtable",hashtable,hashtable.entrySet());
    }
   
     @SuppressWarnings({ "rawtypes"})
     static void retrieveValues(String var1,String var2,Collection collection) {
         System.out.println(var1+" interface using "+var2+" class");
          Iterator iterator = collection.iterator();
          while (iterator.hasNext()) {
             String string = (String) iterator.next();
             System.out.println(string);
          }
          System.out.println("===========================");
       }
   
     @SuppressWarnings({ "rawtypes"})
     static void getValues(String var1,String var2,Map map,Collection collection) {
         System.out.println(var1+" interface using "+var2+" class");
          Iterator iterator = collection.iterator();
          while (iterator.hasNext()) {
             String key = (String) iterator.next();
             String value = (String)map.get(key);
             System.out.println("key:"+key+" value:"+value);
          }
          System.out.println("===========================");
       }
   
     @SuppressWarnings({ "rawtypes"})
     static void displayValues(String var1,String var2,Map map,Collection collection) {
         System.out.println(var1+" interface using "+var2+" class");
       
         Set set = (Set) collection;
          Iterator iterator = set.iterator();
          while (iterator.hasNext()) {
              Map.Entry entry = (Map.Entry) iterator.next();
              String key = (String) entry.getKey();
              String value = (String) entry.getValue();
             System.out.println("key:"+key+" value:"+value);
          }
          System.out.println("===========================");
       }

}

Set Interface Examples

package com.ram;

import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeSet;

/**
 *
 * @author ramakrishna.v
 *
 */
public class SetInterfactExamples {
   
    public static void main(String args[]) {
       
            Set<String> hashSet = new HashSet<String>();
            hashSet.add("a");
            hashSet.add("b");
            hashSet.add("c");
            retrieveValues("Set","HashSet",hashSet);
           
            Set<String> treeSet1 = new TreeSet<String>();
            treeSet1.add("R");
            treeSet1.add("A");
            treeSet1.add("M");
            retrieveValues("Set","TreeSet",treeSet1);
           
            SortedSet<String> treeSet2 = new TreeSet<String>();
            treeSet2.add("R");
            treeSet2.add("A");
            treeSet2.add("M");
            retrieveValues("SortedSet","TreeSet",treeSet2);
           
            Set<String> linkedHashset = new LinkedHashSet<String>();
            linkedHashset.add("R");
            linkedHashset.add("A");
            linkedHashset.add("M");
            retrieveValues("Set","LinkedHashSet",linkedHashset);
    }
   
    @SuppressWarnings({ "rawtypes"})
     static void retrieveValues(String var1,String var2,Collection collection) {
         System.out.println(var1+" interface using "+var2+" class");
          Iterator iterator = collection.iterator();
          while (iterator.hasNext()) {
             String string = (String) iterator.next();
             System.out.println(string);
          }
          System.out.println("===========================");
       }
}

List Interface Examples

package com.ram;

import java.util.Collection;
import java.util.Iterator;

import java.util.List;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.Stack;
import java.util.Vector;

/**
 *
 * @author ramakrishna.v
 *
 */
public class ListInterfaceExamples {

    public static void main(String[] args) {
       
        List<String> arayList = new ArrayList<String>();
        arayList.add("R");
        arayList.add("A");
        arayList.add("M");
        retrieveValues("List","ArrayList",arayList);
       
        List<String> linkedList = new LinkedList<String>();
        linkedList.add("R");
        linkedList.add("A");
        linkedList.add("M");
        retrieveValues("List","LinkedList",linkedList);
       
        List<String> stack = new Stack<String>();
        stack.add("R");
        stack.add("A");
        stack.add("M");
        retrieveValues("List","Stack",stack);
       
        List<String> vector = new Vector<String>();
        vector.add("R");
        vector.add("A");
        vector.add("M");
        retrieveValues("List","Vector",vector);
       
       }
   
     @SuppressWarnings({ "rawtypes"})
     static void retrieveValues(String var1,String var2,Collection collection) {
         System.out.println(var1+" interface using "+var2+" class");
          Iterator iterator = collection.iterator();
          while (iterator.hasNext()) {
             String string = (String) iterator.next();
             System.out.println(string);
          }
          System.out.println("===========================");
       }
    }