diff --git a/Java/Find_Double_Element.java b/Java/Find_Double_Element.java
new file mode 100644
index 0000000..b3cd407
--- /dev/null
+++ b/Java/Find_Double_Element.java
@@ -0,0 +1,18 @@
+package Array;
+// https://leetcode.com/problems/check-if-n-and-its-double-exist/
+public class Find_Double_Element {
+    public boolean checkIfExist(int[] arr) {
+        for(int i=0;i<arr.length;i++){
+            for(int j=0;j<arr.length;j++){
+                if(arr[i]==(2*arr[j])){
+                    if((arr[i]==0) && j!=i)
+                        return true;
+                    if(arr[i]!=0)
+                        return true;
+
+                }
+            }
+        }
+        return false;
+    }
+}
diff --git a/Java/sum_of_array.java b/Java/sum_of_array.java
new file mode 100644
index 0000000..8c31752
--- /dev/null
+++ b/Java/sum_of_array.java
@@ -0,0 +1,24 @@
+package Array;
+
+public class sum_of_array {
+    public int[] plusOne(int[] digits) {
+        if(digits != null && digits.length > 0){
+            int len = digits.length;
+            int carry = 1;
+            for(int i = len-1; i >= 0; i--){
+                int sum = digits[i]+carry;
+                digits[i] = sum > 9 ? sum-10 : sum;
+                carry = sum > 9 ? 1 : 0;
+            }
+            if(carry == 1){
+                int[] newDigits = new int[len+1];
+                newDigits[0] = 1;
+                for(int i = 1; i < len+1; i++){
+                    newDigits[i] = digits[i-1];
+                }
+                return newDigits;
+            }
+        }
+        return digits;
+    }
+}