added java backend (logic only)

UrlShortenerData.java

@@ -0,0 +1,38 @@
+package backendAlex;
+
+
+public class UrlShortenerData {
+
+    private String longUrl;
+
+    private String shortUrl;
+    
+    // Default constructor (required for Jackson)
+    public UrlShortenerData() {
+    }
+    
+    // Optional: Convenience constructor
+    public UrlShortenerData(String longUrl, String shortUrl) {
+        this.longUrl = longUrl;
+        this.shortUrl = shortUrl;
+    }
+    
+    // Standard Setter für longUrl
+    public void setLongUrl(String longUrl) {
+        this.longUrl = longUrl;
+    }
+    
+    // Standard Setter für shortUrl
+    public void setShortUrl(String shortUrl) {
+        this.shortUrl = shortUrl;
+    }
+    
+    // Getter
+    public String getLongUrl() {
+        return this.longUrl;
+    }
+    
+    public String getShortUrl() {
+        return this.shortUrl;
+    }
+}