diff --git a/problems/0205.同构字符串.md b/problems/0205.同构字符串.md
index 4e963ece..06ea5701 100644
--- a/problems/0205.同构字符串.md
+++ b/problems/0205.同构字符串.md
@@ -68,6 +68,25 @@ public:
 ## Java
 
 ```java
+class Solution {
+    public boolean isIsomorphic(String s, String t) {
+        Map<Character, Character> map1 = new HashMap<>();
+        Map<Character, Character> map2 = new HashMap<>();
+        for (int i = 0, j = 0; i < s.length(); i++, j++) {
+            if (!map1.containsKey(s.charAt(i))) {
+                map1.put(s.charAt(i), t.charAt(j)); // map1保存 s[i] 到 t[j]的映射
+            }
+            if (!map2.containsKey(t.charAt(j))) {
+                map2.put(t.charAt(j), s.charAt(i)); // map1保存 t[j] 到 s[i]的映射
+            }
+            // 无法映射，返回 false
+            if (map1.get(s.charAt(i)) != t.charAt(j) || map2.get(t.charAt(j)) != s.charAt(i)) {
+                return false;
+            }
+        }
+        return true;
+    }
+}
 ```
 
 ## Python