I have a logcat.txt file and I have to select only some field from it. I try to explain it better with my specific case:

file.txt

```
I/Xposed  ( 2559): Droidmon-apimonitor-com.astrolog.great.little.war.game.free:{"timestamp":1463412946569,"result":"","class":"android.os.SystemProperties","method":"get","type":"content","args":["debug.second-display.pkg"]}
I/Xposed  ( 2559): Droidmon-apimonitor-com.astrolog.great.little.war.game.free:{"timestamp":1463412946637,"result":"","class":"android.os.SystemProperties","method":"get","type":"content","args":["gsm.sim.operator.iso-country"]}
I/Xposed  ( 2559): Droidmon-apimonitor-com.astrolog.great.little.war.game.free:{"timestamp":1463412946637,"result":"","class":"android.telephony.TelephonyManager","method":"getSimCountryIso","type":"fingerprint","args":[]}
I/Xposed  ( 2559): Droidmon-apimonitor-com.astrolog.great.little.war.game.free:{"timestamp":1463412949364,"result":"","class":"android.os.SystemProperties","method":"get","type":"content","args":["gsm.sim.operator.iso-country"]}
I/Xposed  ( 2559): Droidmon-apimonitor-com.astrolog.great.little.war.game.free:{"timestamp":1463412949364,"result":"","class":"android.telephony.TelephonyManager","method":"getSimCountryIso","type":"fingerprint","args":[]}
I/Xposed  ( 2559): Droidmon-apimonitor-com.astrolog.great.little.war.game.free:{"timestamp":1463412949365,"class":"android.app.ContextImpl","method":"registerReceiver","type":"binder","args":["horoscope.android.LicenseActivity$3@52828f54",{"mPriority":0,"mActions":["SMS_SENT"],"mHasPartialTypes":false}]}
I/Xposed  ( 2559): Droidmon-apimonitor-com.astrolog.great.little.war.game.free:{"timestamp":1463412949373,"class":"android.app.ContextImpl","method":"registerReceiver","type":"binder","args":["horoscope.android.LicenseActivity$3@52828f54",{"mPriority":0,"mActions":["SMS_SENT"],"mHasPartialTypes":false}]}
I/Xposed  ( 2559): Droidmon-apimonitor-com.astrolog.great.little.war.game.free:{"timestamp":1463412949380,"class":"android.app.ContextImpl","method":"registerReceiver","type":"binder","args":["horoscope.android.LicenseActivity$4@52931658",{"mPriority":0,"mActions":["SMS_DELIVERED"],"mHasPartialTypes":false}]}
I/Xposed  ( 2559): Droidmon-apimonitor-com.astrolog.great.little.war.game.free:{"timestamp":1463412949384,"class":"android.app.ContextImpl","method":"registerReceiver","type":"binder","args":["horoscope.android.LicenseActivity$4@52931658",{"mPriority":0,"mActions":["SMS_DELIVERED"],"mHasPartialTypes":false}]}
I/Xposed  ( 2559): Droidmon-apimonitor-com.astrolog.great.little.war.game.free:{"timestamp":1463412949404,"class":"javax.crypto.spec.SecretKeySpec","method":"javax.crypto.spec.SecretKeySpec","type":"crypto","args":["\n0x00000000 0A F9 E4 5D BB DB CE 8B 57 27 4D 5A 1C 2A 37 7D ...]....W'MZ.*7}","AES"]}
I/Xposed  ( 2559): Droidmon-apimonitor-com.astrolog.great.little.war.game.free:{"timestamp":1463412949404,"class":"javax.crypto.spec.SecretKeySpec","method":"javax.crypto.spec.SecretKeySpec","type":"crypto","args":["\n0x00000000 0A F9 E4 5D BB DB CE 8B 57 27 4D 5A 1C 2A 37 7D ...]....W'MZ.*7}","AES"]}

```

So from this file I have to select, for each line, only "class":"*","method":"*". The result must be like this:

`{"class":"android.os.SystemProperties","method":"get"}`  

`{"class":"android.os.SystemProperties","method":"get"}`
`{"class":"android.telephony.TelephonyManager","method":"getSimCountryIso"}`
`{"class":"android.os.SystemProperties","method":"get"}`
`{"class":"android.telephony.TelephonyManager","method":"getSimCountryIso"}`
`{"class":"javax.crypto.spec.SecretKeySpec","method":"javax.crypto.spec.SecretKeySpec"}`
`{"class":"javax.crypto.spec.SecretKeySpec","method":"javax.crypto.spec.SecretKeySpec"}`

I'm trying to do this with a sed command but I can't.