[BAEL-5553] Check whether a string is valid JSON in Java (#12136)

* [BAEL-5553] Check whether a string is valid JSON in Java

* [BAEL-5553] Move implementation to json-2 package

* [BAEL-5553] Move mapper creation outside method

json-2/src/main/java/com/baeldung/jsonvalidation/GsonValidator.java

@@ -0,0 +1,32 @@
+package com.baeldung.jsonvalidation;
+
+import java.io.IOException;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonParser;
+import com.google.gson.JsonSyntaxException;
+import com.google.gson.TypeAdapter;
+
+public class GsonValidator {
+
+    final TypeAdapter<JsonElement> strictAdapter = new Gson().getAdapter(JsonElement.class);
+
+    public boolean isValid(String json) {
+        try {
+            JsonParser.parseString(json);
+        } catch (JsonSyntaxException e) {
+            return false;
+        }
+        return true;
+    }
+
+    public boolean isValidStrict(String json) {
+        try {
+            strictAdapter.fromJson(json);
+        } catch (JsonSyntaxException | IOException e) {
+            return false;
+        }
+        return true;
+    }
+}