# Find the position of an element in a Java TreeMap

Given an element N and a TreeMap, the task is to find the position of this element in the given TreeMap in Java.

Examples:

Input: TreeMap = {10=Geeks, 15=4, 20=Geeks, 25=Welcomes, 30=You}, N = 20
Output: 2

Input: TreeMap = {10=Geeks, 15=4, 20=Geeks, 25=Welcomes, 30=You}, N = 5
Output: -1

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach:

• There is no direct method to find out the position of the key in a TreeMap.
• However, we can use TreeMap headMap() method.
• The method returns the portion of the treemap whose keys are strictly less than that of the key_point.
• Hence, if the key exists in the TreeMap, then the size() of its headMap is equal to the position of the key in the TreeMap.

Below is the implementation of the above approach:

 `// Java code to find the position ` `// of an element in a Java TreeMap ` ` `  `import` `java.util.*; ` ` `  `public` `class` `Tree_Map_Demo { ` ` `  `    ``// Function to return the position of ` `    ``// the specified element in the given TreeMap ` `    ``public` `static` ` ``int` `findPosition(K N, TreeMap tree_map) ` `    ``{ ` `        ``int` `pos = -``1``; ` ` `  `        ``// Check if the given key ` `        ``// is present or not ` `        ``if` `(tree_map.containsKey(N)) { ` ` `  `            ``// If present, find the position ` `            ``// using the size of headMap() ` ` `  `            ``pos = tree_map.headMap(N).size(); ` `        ``} ` ` `  `        ``return` `pos; ` `    ``} ` ` `  `    ``// Function to print the result ` `    ``public` `static` ` ``void` `printResult(K N, TreeMap tree_map) ` `    ``{ ` ` `  `        ``// Get the position ` `        ``int` `pos = findPosition(N, tree_map); ` ` `  `        ``// Print the result ` `        ``if` `(pos >= ``0``) { ` ` `  `            ``System.out.println(N + ``" found at "` `                               ``+ ``"position = "` `+ pos); ` `        ``} ` `        ``else` `{ ` ` `  `            ``System.out.println(N + ``" not found. "` `                               ``+ ``"Hence position = "` `                               ``+ pos); ` `        ``} ` `    ``} ` ` `  `    ``// Driver code ` `    ``public` `static` `void` `main(String[] args) ` `    ``{ ` ` `  `        ``// Creating an empty TreeMap ` `        ``TreeMap tree_map ` `            ``= ``new` `TreeMap(); ` ` `  `        ``// Mapping string values to int keys ` `        ``tree_map.put(``10``, ``"Geeks"``); ` `        ``tree_map.put(``15``, ``"4"``); ` `        ``tree_map.put(``20``, ``"Geeks"``); ` `        ``tree_map.put(``25``, ``"Welcomes"``); ` `        ``tree_map.put(``30``, ``"You"``); ` ` `  `        ``// Displaying the TreeMap ` `        ``System.out.println(``"TreeMap: "` `+ tree_map); ` ` `  `        ``// Element of which position is to be found ` `        ``int` `N1 = ``20``, N2 = ``5``; ` ` `  `        ``// Get the position ` `        ``printResult(N1, tree_map); ` `        ``printResult(N2, tree_map); ` `    ``} ` `} `

Output:

```TreeMap: {10=Geeks, 15=4, 20=Geeks, 25=Welcomes, 30=You}
20 found at position = 2
```

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