[英]Nullable Annotation not appears in field
I'm using Java Reflections for get model's fields and some fields are Nullables with the @Nullable annotation. 我正在使用Java Reflections获取模型的字段,并且某些字段是带有@Nullable批注的Nullables。
public class Category implements Serializable {
private String id;
private String name;
@Nullable
private String description;
@Nullable
private String urlIcon;
private ArrayList<String> sounds;
//Getters and setters
}
And when I try to get the annotations of fields, any field has annotations :( I don't know why. 当我尝试获取字段的注释时,任何字段都具有注释:(我不知道为什么。
Can you help me please. 你能帮我吗。
public static <T> String getCreateSentence(Class<T> clazz) {
StringBuilder sentence = new StringBuilder("CREATE TABLE " + clazz.getSimpleName() + " (");
//Loop for ever field in Model
for (Field field : clazz.getDeclaredFields()) {
if (field.getType().isPrimitive() && !field.getName().equals("serialVersionUID")) {
if (field.getType().equals(Integer.TYPE)
|| field.getType().equals(Boolean.TYPE)
|| field.getType().equals(Byte.TYPE)
|| field.getType().equals(Long.TYPE)
|| field.getType().equals(Short.TYPE)) {
//field.isAnnotation is false ever and field.getDeclaredAnnotations has 0 items ever
if (field.isAnnotationPresent(Nullable.class)) {
sentence.append(field.getName()).append(" INT NULL, ");
} else {
sentence.append(field.getName()).append(" INT NOT NULL, ");
}
} else {
//I evaluate another field types
}
}
}
return sentence.substring(0, sentence.lastIndexOf(",")) + ");";
}
Nullable annotation is not retained for reflective access. 不保留可为空的注释以进行反射访问。 I cannot use it for this.
我不能为此使用它。 I need write my own annotation with Retained annotation for use and get it whit java refelctions.
我需要使用保留的注释编写自己的注释以供使用,并将其添加到Java refelctions中。
Like this: http://www.java2s.com/Tutorials/Java/java.lang.reflect/Field/Java_Field_getAnnotation_Class_lt_T_gt_annotationClass_.htm 像这样: http : //www.java2s.com/Tutorials/Java/java.lang.reflect/Field/Java_Field_getAnnotation_Class_lt_T_gt_annotationClass_.htm
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