feat: java code : Leetcode-1768

Author: KGK-7

Merge Strings Alternately.java

@@ -0,0 +1,18 @@
+class Solution {
+    public String mergeAlternately(String word1, String word2) {
+        StringBuilder mergedWord = new StringBuilder();
+        int i = 0;
+        int w1=word1.length();
+        int w2=word2.length();
+        while(i< w1|| i< w2){
+            if(i< w1){
+                mergedWord.append(word1.charAt(i));
+            }
+            if(i < w2){
+                mergedWord.append(word2.charAt(i));
+            }
+            i++;
+        } 
+        return mergedWord.toString();
+    }
+}