Android JSONObject 需要打印 null

Question

data from:

{"i":"One","o":"two","u":"","a":"four"}

code:

JSONObject data;
for (int i = 0; i < list.length(); i++) {
  data = list.optJSONObject(i);
  mSearchList.add(data.optString("o") + " " + 
            data.optString("u")+ " " + data.optString("a"));
}

print:

i=one o=two u= a=four

I need print:

i=one o=two u=null a=four

how to do?Thank you read my question ,please help me

Answer 1

As Sotirios Delimanolis said, you can check if that is a empty string, return "null" text.

for (int i = 0; i < list.length(); i++) {
  data = list.optJSONObject(i);
  mSearchList.add(
            data.optString("o").equals("") ? "null" : data.optString("o") + " " + 
            data.optString("u").equals("") ? "null" : data.optString("u") + " " + 
            data.optString("a").equals("") ? "null" : data.optString("a"));
}

Answer 2

Use this method

getValidString(JSONObject json,String key){
    String value="";
    try{
      value=json.getString(key);
    }catch(Exception e){
      e.printStackTrace();
    }
    if(value.length==0){
      value="null";
    }
}