How to use

getElementTypeDescriptor

method

in

org.springframework.core.convert.TypeDescriptor

@Override
public boolean matches(TypeDescriptor sourceType, TypeDescriptor targetType) {
  return ConversionUtils.canConvertElements(
      sourceType.getElementTypeDescriptor(), targetType.getElementTypeDescriptor(), this.conversionService);
}

@Override
public boolean matches(TypeDescriptor sourceType, TypeDescriptor targetType) {
  return ConversionUtils.canConvertElements(sourceType.getElementTypeDescriptor(),
      targetType.getElementTypeDescriptor(), this.conversionService);
}

@Override
public boolean matches(TypeDescriptor sourceType, TypeDescriptor targetType) {
  return (targetType.getElementTypeDescriptor() == null ||
      this.conversionService.canConvert(sourceType, targetType.getElementTypeDescriptor()));
}

@Override
public boolean matches(TypeDescriptor sourceType, TypeDescriptor targetType) {
  return ConversionUtils.canConvertElements(sourceType, targetType.getElementTypeDescriptor(),
      this.conversionService);
}

@Override
public void setValue(@Nullable Object newValue) {
  TypeDescriptor elementType = this.typeDescriptor.getElementTypeDescriptor();
  Assert.state(elementType != null, "No element type");
  setArrayElement(this.typeConverter, this.array, this.index, newValue, elementType.getType());
}

@Override
public boolean matches(TypeDescriptor sourceType, TypeDescriptor targetType) {
  return ConversionUtils.canConvertElements(sourceType, targetType.getElementTypeDescriptor(),
      this.conversionService);
}

@Nullable
private Object convertFromStream(@Nullable Stream<?> source, TypeDescriptor streamType, TypeDescriptor targetType) {
  List<Object> content = (source != null ? source.collect(Collectors.<Object>toList()) : Collections.emptyList());
  TypeDescriptor listType = TypeDescriptor.collection(List.class, streamType.getElementTypeDescriptor());
  return this.conversionService.convert(content, listType, targetType);
}

private Object convertToStream(@Nullable Object source, TypeDescriptor sourceType, TypeDescriptor streamType) {
  TypeDescriptor targetCollection = TypeDescriptor.collection(List.class, streamType.getElementTypeDescriptor());
  List<?> target = (List<?>) this.conversionService.convert(source, sourceType, targetCollection);
  if (target == null) {
    target = Collections.emptyList();
  }
  return target.stream();
}

@Override
public boolean matches(TypeDescriptor sourceType, TypeDescriptor targetType) {
  if (sourceType.isAssignableTo(STREAM_TYPE)) {
    return matchesFromStream(sourceType.getElementTypeDescriptor(), targetType);
  }
  if (targetType.isAssignableTo(STREAM_TYPE)) {
    return matchesToStream(targetType.getElementTypeDescriptor(), sourceType);
  }
  return false;
}

@Test
public void passDownGeneric() throws Exception {
  TypeDescriptor td = new TypeDescriptor(getClass().getField("passDownGeneric"));
  assertEquals(List.class, td.getElementTypeDescriptor().getType());
  assertEquals(Set.class, td.getElementTypeDescriptor().getElementTypeDescriptor().getType());
  assertEquals(Integer.class, td.getElementTypeDescriptor().getElementTypeDescriptor().getElementTypeDescriptor().getType());
}

@Test
public void createCollectionWithNullElement() throws Exception {
  TypeDescriptor typeDescriptor = TypeDescriptor.collection(List.class, null);
  assertThat(typeDescriptor.getElementTypeDescriptor(), nullValue());
}

@Test
public void elementTypePreserveContext() throws Exception {
  TypeDescriptor desc = new TypeDescriptor(getClass().getField("listPreserveContext"));
  assertEquals(Integer.class, desc.getElementTypeDescriptor().getElementTypeDescriptor().getType());
  List<Integer> value = new ArrayList<>(3);
  desc = desc.elementTypeDescriptor(value);
  assertEquals(Integer.class, desc.getElementTypeDescriptor().getType());
  assertNotNull(desc.getAnnotation(FieldAnnotation.class));
}

@Test
public void propertyComplex() throws Exception {
  Property property = new Property(getClass(), getClass().getMethod("getComplexProperty"),
      getClass().getMethod("setComplexProperty", Map.class));
  TypeDescriptor desc = new TypeDescriptor(property);
  assertEquals(String.class, desc.getMapKeyTypeDescriptor().getType());
  assertEquals(Integer.class, desc.getMapValueTypeDescriptor().getElementTypeDescriptor().getElementTypeDescriptor().getType());
}

@Test
public void fieldComplexTypeDescriptor() throws Exception {
  TypeDescriptor typeDescriptor = new TypeDescriptor(TypeDescriptorTests.class.getDeclaredField("arrayOfListOfString"));
  assertTrue(typeDescriptor.isArray());
  assertEquals(List.class,typeDescriptor.getElementTypeDescriptor().getType());
  assertEquals(String.class, typeDescriptor.getElementTypeDescriptor().getElementTypeDescriptor().getType());
  assertEquals("java.util.List<java.lang.String>[]",typeDescriptor.toString());
}

@Test
public void propertyGenericTypeList() throws Exception {
  GenericType<Integer> genericBean = new IntegerType();
  Property property = new Property(getClass(), genericBean.getClass().getMethod("getListProperty"),
      genericBean.getClass().getMethod("setListProperty", List.class));
  TypeDescriptor desc = new TypeDescriptor(property);
  assertEquals(List.class, desc.getType());
  assertEquals(Integer.class, desc.getElementTypeDescriptor().getType());
}

@Test
public void elementTypeForCollectionSubclass() throws Exception {
  @SuppressWarnings("serial")
  class CustomSet extends HashSet<String> {
  }
  assertEquals(TypeDescriptor.valueOf(CustomSet.class).getElementTypeDescriptor(), TypeDescriptor.valueOf(String.class));
  assertEquals(TypeDescriptor.forObject(new CustomSet()).getElementTypeDescriptor(), TypeDescriptor.valueOf(String.class));
}

@Test
public void fieldMap() throws Exception {
  TypeDescriptor desc = new TypeDescriptor(TypeDescriptorTests.class.getField("fieldMap"));
  assertTrue(desc.isMap());
  assertEquals(Integer.class, desc.getMapKeyTypeDescriptor().getElementTypeDescriptor().getType());
  assertEquals(Long.class, desc.getMapValueTypeDescriptor().getElementTypeDescriptor().getType());
}

@Test
public void property() throws Exception {
  Property property = new Property(
      getClass(), getClass().getMethod("getProperty"), getClass().getMethod("setProperty", Map.class));
  TypeDescriptor desc = new TypeDescriptor(property);
  assertEquals(Map.class, desc.getType());
  assertEquals(Integer.class, desc.getMapKeyTypeDescriptor().getElementTypeDescriptor().getType());
  assertEquals(Long.class, desc.getMapValueTypeDescriptor().getElementTypeDescriptor().getType());
  assertNotNull(desc.getAnnotation(MethodAnnotation1.class));
  assertNotNull(desc.getAnnotation(MethodAnnotation2.class));
  assertNotNull(desc.getAnnotation(MethodAnnotation3.class));
}

@Test
public void projectionTypeDescriptors_2() {
  StandardEvaluationContext context = new StandardEvaluationContext(new C());
  SpelExpressionParser parser = new SpelExpressionParser();
  String el1 = "as.![#this.equals('abc')]";
  SpelExpression exp = parser.parseRaw(el1);
  Object[] value = (Object[]) exp.getValue(context);
  // value is array containing [true,false]
  assertEquals(Boolean.class, value[0].getClass());
  TypeDescriptor evaluated = exp.getValueTypeDescriptor(context);
  assertEquals(Boolean.class, evaluated.getElementTypeDescriptor().getType());
}

@Test
public void valueOfArray() throws Exception {
  TypeDescriptor typeDescriptor = TypeDescriptor.valueOf(int[].class);
  assertTrue(typeDescriptor.isArray());
  assertFalse(typeDescriptor.isCollection());
  assertFalse(typeDescriptor.isMap());
  assertEquals(Integer.TYPE, typeDescriptor.getElementTypeDescriptor().getType());
}