Develop Reference

I get fields of type String with some Unicode characters instead of the usual

My problem is that I am getting strings where some characters are Unicode.
"fieldName": "Ac6jHguQjKKUxx6MSOpjO2kOLKPAdjStVs1pgTGNSU8\u003d"
Then I immediately send such a string to another API and the server returns me an error with a code of 500. If I use this string in postman and replace the unicode with a normal one, then the code 200 is returned from the server.
I thought there was a problem in the server, but they checked it and said that they were sending it as expected.
How do I translate Unicode?

The easiest way is to use URLDecoder. Here is an example.
String str = "Ac6jHguQjKKUxx6MSOpjO2kOLKPAdjStVs1pgTGNSU8\u003d";
String decode = URLDecoder.decode(str, "UTF-8");
System.out.println(decode);
//Ac6jHguQjKKUxx6MSOpjO2kOLKPAdjStVs1pgTGNSU8=

How to add travel word to JSON?

my json is
{[{"key1":"value1","key2":"valu2"},{“ key3":"value3","key4":"valu4”}]}
How to change the above text as follows. Thank you for helping my friends
{"travel": [{"key1":"value1","key2":"valu2"},{ key3":"value3","key4":"value4}]}

Your original String is not a valid JSON for two reasons:
1 we can see some invalid quotes
2 elements inside a json object must have keys.
so assuming that your String is correct to achieve what you need in java you can do the following:
String string="{[{\"key1\":\"value1\",\"key2\":\"valu2\"},{\" key3\":\"value3\",\"key4\":\"valu4\"}]}";
StringBuilder stringBuilder=new StringBuilder(string);
stringBuilder.insert(1,"\"travel\":");
String json=stringBuilder.toString();
You just insert your key after the first character. Hope this will help.

How to avoid nul value in URL in android?

I have a strange issue about using Retrofit2 in my android project. I got the issue about the server error since the request is something like that.
https://www.example.com/api/v1/skills?q=Good%00
Since the invalid value "%00" is not acceptable in our server, so it showed error on my activity.
API service
#GET("skills")
Observable<SearchItem> getSkills(#Query("q") String keyword);
In my fragment, I just get the text using following simple statement.
String keyword = editText.getText().toString()
api.getSkills(keyword);
What I want to know is the following:
Is it possible to have a word can be converted to "%00" ?
How to avoid this "Good%00" before I send to getSkills function?

To enable compile time checks on nullity add #NonNull annotation,
#GET("skills")
Observable<SearchItem> getSkills(#NonNull #Query("q") String keyword);
Another way is to change each "%00" in your string, using .replace()

Replace the string with "" if it contains %00
if (text.toString().contains("%00")){
text = text.replace("%00", "");
}
and then call getSkills(text) with updated value

Try this
Use trim()
The java string trim() method eliminates leading and trailing spaces. The unicode value of space character is '\u0020'. The trim() method in java string checks this unicode value before and after the string, if it exists then removes the spaces and returns the omitted string.
SAMPLE CODE
String keyword = editText.getText().toString().trim();
api.getSkills(keyword)
or your can use
replace()
The java string replace() method returns a string replacing all the old char or CharSequence to new char or CharSequence.
SAMPLE CODE
url =url.replace("%00", "");
or You can use URLEncoder
Utility class for HTML form encoding. This class contains static methods for converting a String to the application/x-www-form-urlencoded MIME format. For more information about HTML form encoding
String encodedurl = URLEncoder.encode(yourURL,"UTF-8");

There is two way to solve this
1. you restrict the entry write below code
android:digits="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
you can add more thing which you want
String keyword = editText.getText().toString().replace("%00", "");
api.getSkills(keyword);

IllegalArgumentException IN ANDROID URL

Using the below url I got an error:
java.lang.IllegalArgumentException: Illegal character in path at index 47: http://safetracker-threetinker.rhcloud.com/api/{userid}/locations?lat={latitude}&lng={longitude}.
URL:
URL=http://safetracker-threetinker.rhcloud.com/api/{userid}/locations?lat={latitude}&lng={longitude}
how to solve the error. I don't have good knowledge in URL encoding. please help me to find the solution.

The problem is actually it is looking for long/integer value and you are passing a { just put a $ so that it will be replaced by the actual value pointed by the variable
http://safetracker-threetinker.rhcloud.com/api/1/locations?lat=5&lng=5
your Address is like this
URL=http://safetracker-threetinker.rhcloud.com/api/{userid}/locations?lat={latitude}&lng={longitude}
it should be like this
URL=http://safetracker-threetinker.rhcloud.com/api/${userid}/locations?lat=${latitude}&lng={longitude}

We can not use some special characters in URL, so we have to replace these special characters with its encoded form.
Replace your URL with following URL
URL=http://safetracker-threetinker.rhcloud.com/api/%7Buserid%7D/locations?lat=%7Blatitude%7D&lng=%7Blongitude%7D
May this help you.

URLEncoder should be the way to go. You only need to keep in mind to encode only the individual query string parameter name and/or value, not the entire URL, for sure not the query string parameter separator character & nor the parameter name-value separator character =.
String q = "replace_with user_id/locations?lat=replace with latitude&lng=replace with longitude";
String url = "http://safetracker-threetinker.rhcloud.com/api/=" + URLEncoder.encode(q, "UTF-8");

Escape sequence string processing in android

I have a string variable in my android ap which contains some url http://www.google.com. The string variable is declared as shown below:
String html="";
But there is an error saying that I have to put (semicolon); after the a href=". But actually I want the entire line content ie
(href="http://www.google.com") in the string variable. How can it be achieved?? Thanks in advance.

doubles quotes needs to escaped.
try below one
String html="<a href='http://www.google.com'></a>";
else
String html= "";

You need to escape every " with \ if you want to put it in one String.
For example:
String html="";
If you don't do this, compiler assumes, that you end this String after href= and tries to understand what http://www.google.com means in Java ;)