Adding auto generated toString method for structs

codegen/src/main/java/org/web3j/codegen/SolidityFunctionWrapper.java

@@ -519,6 +519,7 @@ private List<TypeSpec> buildStructTypes(final List<AbiDefinition> functionDefini
             final TypeSpec.Builder builder =
                     TypeSpec.classBuilder(structName)
                             .addModifiers(Modifier.PUBLIC, Modifier.STATIC);
+                    builder.addMethod(generateToStringMethod(namedType.getComponents())); // ADDED THIS LINE 
 
             final MethodSpec.Builder constructorBuilder =
                     MethodSpec.constructorBuilder()
@@ -602,6 +603,7 @@ private List<TypeSpec> buildStructTypes(final List<AbiDefinition> functionDefini
 
             builder.superclass(namedType.isDynamic() ? DynamicStruct.class : StaticStruct.class);
             builder.addMethod(constructorBuilder.build());
+            builder.addMethod(generateToStringMethod(namedType.getComponents())); // Added this line
             if (useNativeJavaTypes
                     && namedType.getComponents().stream()
                             .anyMatch(
@@ -617,6 +619,27 @@ private List<TypeSpec> buildStructTypes(final List<AbiDefinition> functionDefini
         return structs;
     }
 
+    private MethodSpec generateToStringMethod(List<AbiDefinition.NamedType> components) {
+        MethodSpec.Builder builder = MethodSpec.methodBuilder("toString")
+                .addAnnotation(Override.class)
+                .addModifiers(Modifier.PUBLIC)
+                .returns(String.class);
+
+        StringBuilder format = new StringBuilder("\"" + "{ ");
+        List<Object> args = new ArrayList<>();
+
+        for (AbiDefinition.NamedType component : components) {
+            String fieldName = !SourceVersion.isName(component.getName()) ? 
+                    "_" + component.getName() : component.getName();
+            format.append(fieldName).append("='\" + ").append(fieldName).append(" + \"', ");
+        }
+
+        format.append("}\"");
+
+        builder.addStatement("return " + format.toString());
+        return builder.build();
+    }
+
     @NotNull
     private static String getStructName(String internalType) {
         final String fullStructName = internalType.substring(internalType.lastIndexOf(" ") + 1);

codegen/src/test/java/org/web3j/codegen/GenerateToStringMethodTest.java

@@ -0,0 +1,73 @@
+import org.junit.jupiter.api.Test;
+import java.util.Arrays;
+import java.util.List;
+import static org.junit.jupiter.api.Assertions.*;
+import org.web3j.protocol.core.methods.response.AbiDefinition;
+import com.squareup.javapoet.MethodSpec;
+import javax.lang.model.element.Modifier;
+import java.util.ArrayList;
+import javax.lang.model.SourceVersion;
+
+
+public class GenerateToStringMethodTest {
+
+    @Test
+    public void testGenerateToStringMethod() {
+        // Step 1: Create mock components for the struct fields
+        //AbiDefinition.NamedType component1 = new AbiDefinition.NamedType("name", "string", false);
+        //AbiDefinition.NamedType component2 = new AbiDefinition.NamedType("age", "uint256", false);
+        AbiDefinition.NamedType component1 = new AbiDefinition.NamedType("name", "string", new ArrayList<>(), "", false);
+        AbiDefinition.NamedType component2 = new AbiDefinition.NamedType("age", "string", new ArrayList<>(), "", false);
+
+        // Add components to the list
+        List<AbiDefinition.NamedType> components = Arrays.asList(component1, component2);
+
+        // Step 2: Call the generateToStringMethod() with the components
+        MethodSpec toStringMethod = generateToStringMethod(components);
+
+        // Step 3: Generate the expected toString output
+        //String expectedFormat = "\"{ name='\" + name + \"', age='\" + age + \"' }\"";
+        //String expectedMethod = "return \"{ name='\" + name + \"', age='\" + age + \"' }\";";
+        //assertEquals(expectedMethod, actualMethodBody.trim(), "Generated method does not match expected output.");
+        String actualMethodBody = toStringMethod.toString();
+        System.out.println("Generated Method:\n" + actualMethodBody);
+        System.out.flush();
+
+        StringBuilder format = new StringBuilder("\"{ ");
+        if (!components.isEmpty()) {
+            format.setLength(format.length() - 2);
+        };
+        format.append("}\"");
+        //assertTrue(actualMethodBody.contains("return \"{ name='\" + name + \"', age='\" + age + \"' }\";"));
+
+        // Step 4: Ensure the generated method matches the expected format
+        //String actualMethodBody = toStringMethod.toString();
+        //assertTrue(actualMethodBody.contains("return \"{ name='\" + name + \"', age='\" + age + \"' }\";"));
+        //assertTrue(actualMethodBody.contains(expectedFormat), "The toString method was not generated correctly.");
+        assertTrue(actualMethodBody.contains("return \"{ name='\" + name + \"', age='\" + age + \"' }\";"),
+        "Generated toString method is incorrect.");
+
+    }
+
+    private MethodSpec generateToStringMethod(List<AbiDefinition.NamedType> components) {
+        // Original method code goes here (you can copy the method provided above)
+        MethodSpec.Builder builder = MethodSpec.methodBuilder("toString")
+            .addAnnotation(Override.class)
+            .addModifiers(Modifier.PUBLIC)
+            .returns(String.class);
+
+        StringBuilder format = new StringBuilder("\"{ ");
+        List<Object> args = new ArrayList<>();
+
+        for (AbiDefinition.NamedType component : components) {
+            String fieldName = !SourceVersion.isName(component.getName()) ? 
+                "_" + component.getName() : component.getName();
+            format.append(fieldName).append("='\" + ").append(fieldName).append(" + \"', ");
+        }
+
+        format.append("}\"");
+
+        builder.addStatement("return " + format.toString());
+        return builder.build();
+    }
+}