How to sort a multiple repeated json array into unrepeated string array?

@Dexter .. first i found your json bit typical..as you put

 "entry_log": [
    651
]

whereas entry_log just contain single int..so why jsonarray

you can first format your json like this

{
"error": false,
"entry_log": 651,
"log": [
    {
        "id": 2073,
        "hit": 2,
        "amount": 3,
        "pieces": 2,
        "user_email": "xxxxx",
        "log_time": "2015-05-07 13:05:21"
    },
    {
        "id": 2069,
        "hit": 1,
        "amount": 3,
        "pieces": 4,
        "user_email": "xxxxx",
        "log_time": "2015-05-07 12:05:25"
    },
    {
        "id": 2065,
        "hit": 0,
        "amount": 0,
        "pieces": 0,
        "user_email": "xxxxx",
        "log_time": "2015-05-06 09:05:38"
    }
  ]
}

then you can kept the whole jsonarray of "log" to jsonArray object or serialize to the java object

create equivalent object for this json eg-

public class LogModal {
/**
 * entry_log : 651
 * log : [{"pieces":2,"hit":2,"amount":3,"user_email":"xxxxx","id":2073,"log_time":"2015-05-07 13:05:21"},{"pieces":4,"hit":1,"amount":3,"user_email":"xxxxx","id":2069,"log_time":"2015-05-07 12:05:25"},{"pieces":0,"hit":0,"amount":0,"user_email":"xxxxx","id":2065,"log_time":"2015-05-06 09:05:38"}]
 * error : false
 */
private int entry_log;
private List<LogEntity> log;
private boolean error;

public void setEntry_log(int entry_log) {
    this.entry_log = entry_log;
}

public void setLog(List<LogEntity> log) {
    this.log = log;
}

public void setError(boolean error) {
    this.error = error;
}

public int getEntry_log() {
    return entry_log;
}

public List<LogEntity> getLog() {
    return log;
}

public boolean isError() {
    return error;
}

public class LogEntity {
    /**
     * pieces : 2
     * hit : 2
     * amount : 3
     * user_email : xxxxx
     * id : 2073
     * log_time : 2015-05-07 13:05:21
     */
    private int pieces;
    private int hit;
    private int amount;
    private String user_email;
    private int id;
    private String log_time;

    public void setPieces(int pieces) {
        this.pieces = pieces;
    }

    public void setHit(int hit) {
        this.hit = hit;
    }

    public void setAmount(int amount) {
        this.amount = amount;
    }

    public void setUser_email(String user_email) {
        this.user_email = user_email;
    }

    public void setId(int id) {
        this.id = id;
    }

    public void setLog_time(String log_time) {
        this.log_time = log_time;
    }

    public int getPieces() {
        return pieces;
    }

    public int getHit() {
        return hit;
    }

    public int getAmount() {
        return amount;
    }

    public String getUser_email() {
        return user_email;
    }

    public int getId() {
        return id;
    }

    public String getLog_time() {
        return log_time;
    }
}
}

then use library like jackson/gson to serialize to the java object which helps to fasten your app

ex-

LogModal logmodal=gson.fromJson(jsonString, LogModal);

Note : First fix your json response issue. Refer @Angad Tiwari's answer and for below code json data is took from his answer.

Now to find out counts of each day follow this: Get all unique date

public class LogModal {

    private int entry_log;
    private List<LogEntity> log;
    private boolean error;

    //getter and setter goes here

    List<String> dateList = new ArrayList<String>();
    //get list of unique date from your response
    public List<String> getUniqueDateList() {
        for (LogEntity logEntity : getLog()) {

            String arrayDate = MainActivity.getFormattedDate(logEntity.getLog_time());

            if (!dateList.contains(arrayDate)) {
                dateList.add(arrayDate);
            }
        }
        return dateList;
    }

}

Counting according to date MainActivity.java

    Gson gson = new Gson();
    LogModal logModal = gson.fromJson(response, LogModal.class);

    List<LogEntity> logEntries = logModal.getLog();

    List<DayEntry> dayEntries = new ArrayList<DayEntry>();

    for (String uDate : logModal.getUniqueDateList()) {
        DayEntry entry = new DayEntry();
        long hit = 0, amount = 0, pieces = 0;

        for (LogEntity e : logEntries) {
            String logDate = getFormattedDate(e.getLog_time());
            //counting each day records
            if (compareDate(uDate, logDate)) {
                hit += e.getHit();
                pieces += e.getPieces();
                amount += e.getAmount();
            }
        }
        entry.date = uDate;
        entry.amount = amount;
        entry.pieces = pieces;
        entry.hit = hit;
        dayEntries.add(entry);
    }



    for (DayEntry dayEntity : dayEntries) {
        Log.i("TAG"," Date : "+dayEntity.getDate()+" Hits : "+dayEntity.getHit()+" Amount : "+dayEntity.getAmount());
    }

Date related functions MainActivity.java

//remove hour, minute, second from date 
public static String getFormattedDate(String date) {
    SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd hh:MM:ss");

    SimpleDateFormat date1 = new SimpleDateFormat("yyyy-MM-dd");
    Date d1;
    try {
        d1 = formatter.parse(date);
        String wDate = date1.format(d1);
        return wDate;
    } catch (ParseException e) {
        e.printStackTrace();
    }
    return null;

}

//compare date
public boolean compareDate(String date1, String date2) {
    return date1.equals(date2);
}

Output :
 Date : 2015-05-07 Hits : 3 Amount : 6
 Date : 2015-05-06 Hits : 0 Amount : 0