Using java map for range searches

user_43756 0
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I have a use case where if a number lies between 0-10 it should return 0 and if it lies between 11-20 it should return 1 etc 

0 => 0-3, (0 and 3 are inclusive)
1 => 4-15, (4 and 15 are inclusive)
2 => 16-40, (16 and 40 are inclusive)
3 => 41-88, (41 and 88 are inclusive)
5 => 89-300 (89 and 300 are inclusive)

I was thinking how could I implement and was thinking java maps, but it does not allow range searching

I am interested in something like this , I have a function

int foo() {

}

if foo returns 5 , since it lies between 0 to 10 I would use 0, if foo return 25 it would use 2.

Any ideas

Edit : Actually the ranges are not as simple as 0-10, 11-20. I want to be able to do range searches. Sorry about the confusion. Based on the queries I have added the correct example, the numbers are continous

maps java
6 Answers

Based on John Kugelman's answer I needed something similar for a date range search that had data associated to the date range... Here is an example of how I applied it. "dates" would be your keys and "rangeData" would be the data associated.

  long[] dates = new long[] {
    Instant.parse("1900-01-01T00:00:00Z").toEpochMilli(),
    Instant.parse("1950-01-01T00:00:00Z").toEpochMilli(),
    Instant.parse("1960-01-01T00:00:00Z").toEpochMilli(),
    Instant.parse("1970-01-01T00:00:00Z").toEpochMilli(),
    Instant.parse("1980-01-01T00:00:00Z").toEpochMilli(),
    Instant.parse("1990-01-01T00:00:00Z").toEpochMilli(),
    Instant.parse("2000-01-01T00:00:00Z").toEpochMilli(),
    Instant.parse("2010-01-01T00:00:00Z").toEpochMilli()
  };
  String[] rangeData = new String[] {
    "Before 1900 data", "Before 1950 data", "Before 1960 data", 
    "Before 1970 data", "Before 1980 data", "Before 1990 data", 
    "Before 2000 data", "Before 2010 data"
  };
  
  long searchDate = Instant.parse("1949-02-15T00:00:00Z").toEpochMilli();
  int result = Arrays.binarySearch(dates, searchDate);
  
  System.out.println("Result: " + result); 
  if (result == dates.length) {
      System.out.println("Date is after all ranges");
      System.out.println("Data: none");
  }
  else if (result >= 0) {
      System.out.println("Date is an exact match of " + Instant.ofEpochMilli(dates[result]));
      System.out.println("Data: " + rangeData[result]);
  }
  else {
      int resultIndex = Math.abs(result) - 1;
      System.out.println("Date is before idx: "+ resultIndex + " date " + Instant.ofEpochMilli(dates[resultIndex]));
      System.out.println("Data: " + rangeData[resultIndex]);
  }

Result

Result: -2
Date is before idx: 1 date 1950-01-01T00:00:00Z
Data: Before 1950 data
user_9927850
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