Reading JSON object from txt file in Groovy

Question

I am trying to collect a JSON from a txt file. But my below code seems to keep giving me "nullPointerException".

File f = new File(tempDir+File.separator+'jsonObject.txt')
if (f){
    log.error " file exists $f"
    FileReader f2 = new FileReader(f);
    log.error " file data- $f2"
    if (f2 == null) {
        //do something
    } else {
        JsonSlurper jsonParser = new JsonSlurper();
        game = jsonParser.parse(new FileReader(f));
    }
}

SOLUTION FOUND
Reading a json txt file:

File f = new File(tempDir+File.separator+'jsonObject.txt')
def slurper = new JsonSlurper()
def jsonText = f.getText()
json = slurper.parseText( jsonText )

Writing json to a file:

File g = new File(tempDir+File.separator+'jsonObject.txt')
            g.createNewFile()
            def json = new JsonBuilder()
            json {
                "result" result
                }       
            g.setText(json.toString())

where is the null pointer being thrown? You may also want to look at this question I asked a while back around reading in text files http://stackoverflow.com/questions/15389329/where-to-put-a-text-file-in-grails-and-how-to-get-the-path — andy mccullough, Oct 22 '13 at 16:05
For anyone following this, you don't need to do what the _solution_ here says, you can read from a Reader, and writing can be done via `new File( f ).text = new JsonBuilder( [ result: result ] )` rather than the 7 lines above — tim_yates, Oct 23 '13 at 19:53

score 63 · Accepted Answer · answered Oct 23 '13 at 05:38

63

Please, try this:

import groovy.json.JsonSlurper

def inputFile = new File("D:\\yourPath\\json.txt")
def InputJSON = new JsonSlurper().parseText(inputFile.text)
InputJSON.each{ println it }

answered Oct 23 '13 at 05:38

olyv

3,699
5
37
67

With this solution, I kept getting a _java.io.FileNotFoundException:_ and realized I needed to change `new File` to `readFile` as stated here: https://stackoverflow.com/a/52752719/4535181 and here https://stackoverflow.com/a/38679858/4535181 Additionally, I had to remove the call to the **text** property of `inputFile` – dreamwork801 Oct 02 '20 at 11:49

score 7 · Answer 2 · answered Oct 22 '13 at 16:07

7

try:

File f = new File( tempDir, 'jsonObject.txt' )
if( f.exists() ) {
    def game = f.withReader { r ->
        new JsonSlurper().parse( r )
    }
    println game
}

answered Oct 22 '13 at 16:07

tim_yates

167,322
27
342
338

I use your code exacly, but it shows "nullPointerException" error at JsonSlurper line... – Sanket Deshpande Oct 22 '13 at 16:15
Can you add the actual stack trace to the question? – tim_yates Oct 22 '13 at 17:32

score 1 · Answer 3 · answered May 07 '19 at 06:40

1

Try simple and optimized solution:

import groovy.json.JsonSlurper

try {
File inputFile = new File("your_file_path")
def slurper = new JsonSlurper()
def data = slurper.parse(inputFile)
} catch (Exception e) {
      e.printStackTrace()
    }

answered May 07 '19 at 06:40

Rahul Mahadik

11,668
6
41
54

score 0 · Answer 4 · answered Nov 29 '17 at 09:05

0

parseFile can take a file as an input:

import groovy.json.JsonSlurper

def inputFile = new File("/your/path/my.json")
def InputJSON = new JsonSlurper().parseFile(inputFile, 'UTF-8')
InputJSON.each{ println it }

answered Nov 29 '17 at 09:05

Benjamin Francisoud

11
1
3

2

`public Object parse(File file)` is available in JsonSlurper since version 2.2.0 - see [groovy docs](http://docs.groovy-lang.org/2.2.0/html/gapi/groovy/json/JsonSlurper.html#parse(java.io.File)) – user1053510 Jul 23 '18 at 10:02

Reading JSON object from txt file in Groovy

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