Convert null object to String

Question

I have written an android program to load values to table-row from web service. But value comes null so I need to convert it into a string. Can someone tell me the method to do it?

try{                    

    SoapObject request = service.getRequest();
    SoapSerializationEnvelope envelope = service.getEnvelope(request);
    SoapObject response = service.getResponse(envelope);
    Log.i("Service Master", response.toString());
    int count = response.getPropertyCount();
    for (int i = 0; i < count; i++) {
        SoapObject result = (SoapObject) response.getProperty(i);
        DeleteuserDetails deleteuserDetails=new DeleteuserDetails();
        deleteuserDetails.setUserId(result.getPropertyAsString(4));
        deleteuserDetails.setUserName(result.getPropertyAsString(2));
        deleteuserDetails.setUserRole(result.getPropertyAsString(3));
        deleteuserDetails.setCreatedDate(result.getPropertyAsString(1));
        deleteuserDetails.setCreatedBy(result.getPropertyAsString(0));
        userdetail.add(deleteuserDetails);
    }

Now deleteuserDetails.setCreatedBy(result.getPropertyAsString(0)); gets null value from webservice, so I need to convert it into string "null" .

LogCat:

12-20 18:48:52.608: W/System.err(2174): java.lang.NullPointerException
12-20 18:48:52.608: W/System.err(2174):     at org.ksoap2.serialization.SoapObject.getPropertyAsString(SoapObject.java:165)
12-20 18:48:52.608: W/System.err(2174):     at com.mvss.admin.Deleteuser$deteUserIdLoad.doInBackground(Deleteuser.java:81)
12-20 18:48:52.608: W/System.err(2174):     at com.mvss.admin.Deleteuser$deteUserIdLoad.doInBackground(Deleteuser.java:1)
12-20 18:48:52.608: W/System.err(2174):     at android.os.AsyncTask$2.call(AsyncTask.java:185)
12-20 18:48:52.608: W/System.err(2174):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
12-20 18:48:52.608: W/System.err(2174):     at java.util.concurrent.FutureTask.run(FutureTask.java:137)
12-20 18:48:52.608: W/System.err(2174):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1068)
12-20 18:48:52.608: W/System.err(2174):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:561)
12-20 18:48:52.608: W/System.err(2174):     at java.lang.Thread.run(Thread.java:1096)

Answer 1

Instead of catching the exception or putting conditions, use String.valueOf(result.getPropertyAsString(0));

It will call toString() method of the argument and will convert it to String and if result.getPropertyAsString(0) is null, then it will change it to "null" .

Answer 2

Although it's not a good practice, you can concatenate the null value with "" to make it a String.

For example:

String str=null;
System.out.println((str+"").length()); /// prints 4

Answer 3

result.getPropertyAsString(0) alone will result in a NPE already when the property is internally null. Your stacktrace points to SoapObject.getPropertyAsString(SoapObject.java:165) which should be

public String getPropertyAsString(int index) {
    PropertyInfo propertyInfo = (PropertyInfo) properties.elementAt(index);
    return propertyInfo.getValue().toString();
}

source - it will crash when propertyInfo or propertyInfo.getValue() is null .

To prevent that from happening you need to get the property not via getPropertyAsString but via getProperty and convert it manually to a String .

You can encapsulate that into some utility method

public static String getPropertyAsString(SoapObject object, int index) {
    Object prop = object.getProperty(index);
    if(prop instanceof PropertyInfo) {
        prop = ((PropertyInfo)prop).getValue();
    }
    return String.valueOf(prop); // will make it "null" if it is null
}

and then do

deleteuserDetails.setUserId(getPropertyAsString(result, getPropertyAsString(4)));
deleteuserDetails.setUserName(getPropertyAsString(result, getPropertyAsString(2)));
deleteuserDetails.setUserRole(getPropertyAsString(result, getPropertyAsString(3)));

Answer 4

Try this:

deleteuserDetails.setCreatedBy(result.getPropertyAsString(0) == null ? "null": result.getPropertyAsString(0));

Answer 5

Use this,

try {
    deleteuserDetails.setCreatedBy(result.getPropertyAsString(0).toString());
}
catch(Exception e) {
    deleteuserDetails.setCreatedBy("null");
}

Answer 6

if(result.getPropertyAsString(0)==null)
{
deleteuserDetails.setCreatedBy("");
}
else
{
deleteuserDetails.setCreatedBy(result.getPropertyAsString(0).toString());
}

Answer 7

You can simply check if its null then set a string for it.

if(result.getPropertyAsString(0) == null){
 deleteuserDetails.setCreatedBy("NULL");
}else{
 deleteuserDetails.setCreatedBy(result.getPropertyAsString(0));
}

Answer 8

"Hi this will be " + null;

Prints out "Hi this will be null" in String

Answer 9

Instead of that, place the condition if(String!=null) .

Answer 10

The error comes when you are trying to convert a null value to a String ( mostly it's BigDecimal)

So what you have to do is catch the exception when program tries to convert null to String and set the null value manually for the String variable.

try{
    deleteuserDetails.setUserId(result.getPropertyAsString(4));
}catch (Exception e){
    deleteuserDetails.setUserId(null);
}

Answer 11

to Piggybag ride on what @prateek said.

 String str=null;
    System.out.println((str+""));

Do it without the.length so you can actually just print out the string