how to convert object to string in java

Question

I have a function that returns map value  String  as a generic Object  How do I convert it back to string  I tried toString   but all i get is end Ljava lang String  ff2413  public Object getParameterValue String key        Iterator iterator params entrySet   iterator         while iterator hasNext                  Map Entry me  Map Entry iterator next            String   arr  String   me getValue            log info me getKey   toString       arr 0              if params containsKey key                 log info key     params get key            return params get key               return null      Receiving end  String temp data getParameterValue  request   toString    log info  end  temp     log info me getKey   toString       arr 0    give me an output    email x as com request login projectid as

User · Answer

Might not be so related to the issue above  However if you are looking for a way to serialize Java object as string  this could come in hand  package pt iol security   import java io ByteArrayInputStream  import java io ByteArrayOutputStream  import java io IOException  import java io ObjectInputStream  import java io ObjectOutputStream  import java util zip GZIPInputStream  import java util zip GZIPOutputStream  import org apache commons codec binary Base64   public class ObjectUtil        static final Base64 base64   new Base64         public static String serializeObjectToString Object object  throws IOException           try                   ByteArrayOutputStream arrayOutputStream   new ByteArrayOutputStream                    GZIPOutputStream gzipOutputStream   new GZIPOutputStream arrayOutputStream                   ObjectOutputStream objectOutputStream   new ObjectOutputStream gzipOutputStream                  objectOutputStream writeObject object               objectOutputStream flush                return new String base64 encode arrayOutputStream toByteArray                           public static Object deserializeObjectFromString String objectString  throws IOException  ClassNotFoundException           try                   ByteArrayInputStream arrayInputStream   new ByteArrayInputStream base64 decode objectString                    GZIPInputStream gzipInputStream   new GZIPInputStream arrayInputStream                   ObjectInputStream objectInputStream   new ObjectInputStream gzipInputStream                 return objectInputStream readObject

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The result is not a String but a String    That s why you get this unsuspected printout    Ljava lang String is a signature of an array of String   System out println new String

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This toString-Method works for every Class  where you want to display all the fields and its values     public String toString      StringBuffer sb   new StringBuffer     Field   fields   getClass   getDeclaredFields      Get all fields incl  private ones  for  Field field   fields        try            field setAccessible true           String key field getName            String value           try              value    String  field get this             catch  ClassCastException e               value                        sb append key  append       append value  append   n           catch  IllegalArgumentException e            e printStackTrace          catch  SecurityException e            e printStackTrace          catch  IllegalAccessException e            e printStackTrace              return sb toString

User · Answer

Solution 1  cast  String temp  String data getParameterValue  request      Solution 2  use typed map   Map lt String  String gt  param    So you change Change the return type of your function  public String getParameterValue String key        if params containsKey key                 return params get key             return null      and then no need for cast or toString  String temp data getParameterValue  request

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I m afraid your map contains something other than String objects  If you call toString   on a String object  you obtain the string itself   What you get  Ljava lang String indicates you might have a String array

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maybe you benefit from converting it to JSON string   String jsonString   new com google gson Gson   toJson myObject     in my case  I wanted to add an object to the response headers but you cant add objects to the headers   so to solve this I convert my object to JSON string and in the client side  I will return that string to JSON again

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toString   is a debug info string  The default implementation returns the class name and the system identity hash  Collections return all elements but arrays not   Also be aware of NullPointerException creating the log   In this case a Arrays toString   may help   Object temp   data getParameterValue  request    String log   temp    null    null     temp getClass   isArray     Arrays toString  Object   temp    temp toString     log info  end     temp     You can also use Arrays asList     Object temp   data getParameterValue  request    Object log   temp    null   null    temp getClass   isArray     Arrays asList  Object   temp    temp   log info  end     temp     This may result in a ClassCastException for primitive arrays  int

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You can create toString   method to convert object to string   int bid  String bname  double bprice   Book String str        String   s1   str split  -        bid   Integer parseInt s1 0        bname   s1 1       bprice   Double parseDouble s1 2       public String toString         return bid  -  bname  -  bprice        public static void main String   s        Book b1   new Book  12-JAVA-200 50        System out println b1

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Looking at the output  it seems that your  temp  is a String array  You need to loop across the array to display each value

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To convert serialize object to String and String to Object  stringToBean beanToString new LoginMdp     LoginMdp class    public static String beanToString Object object  throws IOException        ObjectMapper objectMapper   new ObjectMapper        StringWriter stringEmp   new StringWriter        objectMapper configure SerializationFeature INDENT OUTPUT  true       objectMapper writeValue stringEmp  object       return stringEmp toString       public static  lt T gt  T stringToBean String content  Class lt T gt  valueType  throws IOException       return new ObjectMapper   readValue content  valueType

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The question how do I convert an object to a String  despite the several answers you see here  and despite the existence of the Object toString method  is unanswerable  or has infinitely many answers  Because what is being asked for is some kind of text representation or description of the object  and there are infinitely many possible representations  Each representation encodes a particular object instance using a special purpose language  probably a very limited language  or format that is expressive enough to encode all possible object instances   Before code can be written to convert an object to a String  you must decide on the language format to be used

[java] how to convert object to string in java

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