I am having java code:
public class Test {
public static void main(String[] args) {
Student student = new Student(1,"test");
printId(student);
}
private static void printId(Student obj) {
if(Objects.isNull(obj))
return;
System.out.println("Id: " + obj.getId());
}
}
public class Student {
private int id;
private String name;
public Student(int id, String name) {
this.id = id;
this.name = name;
}
public int getId(){
return id;
}
}
At line System.out.println... sonar is showing that obj can be null but I had already checked for null value.
Is there any way to get rid of this issue?
You could use explicit null test.
if(null==obj)
return;
......
The rule itself does not recognize usage of Objects.isNull as null check. Objects.isNull(Object obj) returns result of null==obj expresion so it can be safely replaced.
However you could contact SonarSource and propose rule change.
Related
I am using spring JPA to attempt to write records to a postGres DB. At the time of the commit, I am getting the following error:
Caused by: org.postgresql.util.PSQLException: ERROR: null value in column "col_id" violates not-null constraint
Detail: Failing row contains (null, null, null, null, null)
I have the following repository interface:
public interface MyRepo extends JpaRepository <MyModel, String> {
}
, the following model class:
#Entity
#Validated
#Table(name = "my_table", schema="common")
public class MyModel {
#Id
#Column(name = "col_id")
private String id;
#Column(name = "second_col")
private String secCol;
#Column(name = "third_col")
private String thirdCol;
#Column(name = "fourth_col")
private String fourthCol;
#Column(name = "fifth_col")
private String fifthCol;
public MyModel() {
}
public MyModel(String id, String secCol, String thirdCol, String fourthCol, String fifthCol) {
this.id = id;
this.secCol = secCol;
this.thirdCol = thirdCol;
this.fourthCol = fourthCol;
this.fifthCol = fifthCol;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getSecCol() {
return secCol;
}
public void setSecCol(String secCol) {
this.secCol = secCol;
}
public String getThirdCol() {
return thirdCol;
}
public void setThirdCol(String thirdCol) {
this.thirdCol = thirdCol;
}
public String getFourthCol() {
return fourthCol;
}
public void setFourthCol(String fourthCol) {
this.fourthCol = fourthCol;
}
public String getFifthCol() {
return fifthCol;
}
public void setFifthCol(String fifthCol) {
this.fifthCol = fifthCol;
}
}
, and the relevant part of the service class:
public MyModel myModel (MyModel myModel) {
MyModel mm = null;
try {
mm = myRepo.saveAndFlush(myModel);
} catch ( Exception e) {
e.printStackTrace();
}
return mm;
}
UPDATE:
I finally realized that my problem is due to a database trigger that auto-generates primary key against a complex business rule. Also, I assume I might need to use a custom save method rather than the default repo.saveAndFlush? I would be grateful for any ideas given new information. Thanks!
I reproduced the exact same code in a test project with Postgres and it worked well for me. You are absolutely correct that the values of the model class are not populated. You must share your controller also. It may really help me to help you if I can get a look where your service is being called from. Only that will help me to deduce why your model values are being passed as null in the service call.
I'm playing a little bit with Optional to understand how it works. Let's say I have this class:
public class Student {
private int id;
private String name;
public Student(int id, String name) {
this.id = id;
this.name = name;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
and I want to return a Student by Id or Optional.empty if it doesn't find it. This is what I have so far:
public class Main {
static List<Student> students = new ArrayList<>();
public static void main(String[] args) {
students.add(new Student(1, "name1"));
students.add(new Student(2, "name2"));
students.add(new Student(3, "name3"));
System.out.println(getStudentById(1).get().getName());
}
public static Optional<Student> getStudentById(int id) {
return students
.stream()
.filter( s -> s.getId() == id)
.findFirst();
}
}
That works but I wanted to add this line:
.findFirst()
.orElse(Optional.empty());
and I got this:
Error:(23, 39) java: incompatible types: no instance(s) of type variable(s) T exist so that java.util.Optional conforms to com.company.Student
Also I'd like to know if that is the correct way to go over a list, I mean element by element or there is something better?
If you read javadocs of Stream#findFirst() you will find that you already have what you need:
Returns an Optional describing the first element of this stream, or an
empty Optional if the stream is empty. If the stream has no encounter
order, then any element may be returned.
So just do
return students
.stream()
.filter( s -> s.getId() == id)
.findFirst();
I have a query to My SQL database and I use Spring Boot to return it to Json format.
My problem is it only return value without key like:
[
[
"kermit",
6
]
]
I want it return like:
[
[
"name":"kermit",
"count" :6
]
]
I tried add Jackson Annotation jar file to project and use #JsonProperty in my entity model class:
#Entity
#Table(name = "act_id_membership", schema = "activiti", catalog = "")
#IdClass(ActIdMembershipEntityPK.class)
public class ActIdMembershipEntity {
#JsonProperty("name")
private String userId;
#JsonProperty("group")
private String groupId;
#Id
#Column(name = "USER_ID_")
public String getUserId() {
return userId;
}
public void setUserId(String userId) {
this.userId = userId;
}
#Id
#Column(name = "GROUP_ID_")
public String getGroupId() {
return groupId;
}
public void setGroupId(String groupId) {
this.groupId = groupId;
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
ActIdMembershipEntity that = (ActIdMembershipEntity) o;
return Objects.equals(userId, that.userId) &&
Objects.equals(groupId, that.groupId);
}
#Override
public int hashCode() {
return Objects.hash(userId, groupId);
}
}
But it still return without key. What I should do now? Please help me!
Thank you very much!
First, I'm agree with guy who commented that is not valid JSON format. You can see examples here https://json.org/example.html
Second, You need to create an object JSON which has fields needed for example:
public class UserStat es implements Serializable {
private String name;
private long count;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public long getCount() {
return count;
}
public void setCount(long count) {
this.count = count;
}
}
And in your custom query. Based your return looks like on this way:
#Query("SELECT u.name, count(u) FROM User u")
public List<UserStat> findUserStat() ;
I have a pojo class of emp like below:
I am able to read streaming data and I want to insert data to Hbase
#JsonInclude(Include.NON_NULL)
public class empData implements Serializable {
private String id;
private String name;
#Override
public String toString() {
return "id=" + id + ", name="+ name ;
}
public String id() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
Below is spark code:
empRecords.foreachRDD(new Function<JavaRDD<empData>, Void>() {
private static final long serialVersionUID = 1L;
#Override
public Void call(JavaRDD<empData> empDataEvent)throws Exception {
Configuration conf = HBaseConfiguration.create();
Configuration config = null;
config = HBaseConfiguration.create();
config.set("hbase.zookeeper.quorum", "**********);
HBaseAdmin.checkHBaseAvailable(config);
config.set(TableInputFormat.INPUT_TABLE, "tableName");
Job newAPIJobConfiguration1 = Job.getInstance(config);
newAPIJobConfiguration1.getConfiguration().set(TableOutputFormat.OUTPUT_TABLE, "empHbase");
newAPIJobConfiguration1.setOutputFormatClass(org.apache.hadoop.hbase.mapreduce.TableOutputFormat.class);
JavaPairRDD<ImmutableBytesWritable, Put> inesrts = empData.mapToPair(new PairFunction<Row, ImmutableBytesWritable, Put>() {
public Tuple2<ImmutableBytesWritable, Put> call(Row row) throws Exception
{
Put put = new Put(Bytes.toBytes(row.getString(0)));
put.add(Bytes.toBytes("empA"),Bytes.toBytes("id"),Bytes.toBytes(row.getString(1)));
put.add(Bytes.toBytes("empA"),Bytes.toBytes("name"),Bytes.toBytes(row.getString(2)));
return new Tuple2<ImmutableBytesWritable, Put>(new ImmutableBytesWritable(), put);
}
});
inserts.saveAsNewAPIHadoopDataset(newAPIJobConfiguration1.getConfiguration());
}
});
jssc.start();
jssc.awaitTermination();
}
The problem in the code is this step:
JavaPairRDD<ImmutableBytesWritable, Put> inesrts =empDataEvent.mapToPair(new PairFunction<Row, ImmutableBytesWritable, Put>()
How to use empDataEvent and how to insert..
How do I insert as mapToPair empDataEvent class object so that I can insert into Hbase.
Any help appreciated..
Aman,
In your code you have refer "Row", can you please elaborate where it is coming from? because there is no reference for it.
See updated code below, use class name "empData" instead of "Row" object.
JavaPairRDD<ImmutableBytesWritable, Put> inesrts = empData.mapToPair(new PairFunction<empData, ImmutableBytesWritable, Put>() {
public Tuple2<ImmutableBytesWritable, Put> call(empData row) throws Exception
{
Put put = new Put(Bytes.toBytes(row.id));
put.add(Bytes.toBytes("empA"),Bytes.toBytes("id"),Bytes.toBytes(row.id));
put.add(Bytes.toBytes("empA"),Bytes.toBytes("name"),Bytes.toBytes(row.getName));
return new Tuple2<ImmutableBytesWritable, Put>(new ImmutableBytesWritable(), put);
}
});
I am trying to access getter properties in a subclass with a TableView in JavaFX. I have the following class:
public class PersonType implements Serializable {
private static final long serialVersionUID = 1L;
Person person;
short count;
public PersonType() {
}
public PersonType(Person person, short count) {
super();
this.person = person;
this.count = count;
}
public Person getPerson() {
return person;
}
public void setPerson(Person person) {
this.person = person;
}
public short getCount() {
return count;
}
public void setCount(short count) {
this.count = count;
}
Person is like this:
public class Person implements Serializable {
private static final long serialVersionUID = 1L;
String firstName;
String lastName;
public Person() {
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
}
Okay - lastly we have the following:
#FXML
private TableColumn tcFirstName;
#FXML
private TableColumn tcLastName;
#FXML
private TableView tblPersonTypes;
ArrayList<PersonType> pType = new ArrayList<PersonType>();
//Can assume that pType here has say 5 entries, the point of this
//is I'm trying to get to the firstName, lastName properties of the
//PersonType in the TableView below like the following:
tcFirstName.setCellValueFactory(new PropertyValueFactory<String,String>("firstName"));
tcLastName.setCellValueFactory(new PropertyValueFactory<String,String>("lastName"));
//Populate Table with Card Records
ObservableList<PersonType> data = FXCollections.observableArrayList(pType);
tblPersonTypes.setItems(data);
And I'm unsure how with a list of PersonTypes I can tell the table columns that I want the firstName and lastName properties of the Person object contained within. I know I could create a new object, and have the "count" from PersonTypes, then the other properties of "firstName", "lastName" etc without having an object property of Person. Any help would be greatly appreciated.
-- EDIT --
Another way I thought to do this was using CellFactories - where I would pass in to the CellValueFactories the Person object, then set the CellFactory to return a String value (firstName for the first name column, etc). And it would look like this:
tcFirstName.setCellValueFactory(new PropertyValueFactory<Person,String>("person"));
tcFirstName.setCellFactory(new Callback<TableColumn<Person,String>,TableCell<Person,String>>(){
#Override
public TableCell<Person,String> call(TableColumn<Person,String> param) {
TableCell<Person,String> cell = new TableCell<Person,String>(){
#Override
public void updateItem(String item, boolean empty) {
if(item!=null){
setGraphic(new Label(item.getFirstName()));
}
}
};
return cell;
}
});
Try this:
tcFirstName.setCellValueFactory(new Callback<CellDataFeatures<PersonType, String>, ObservableValue<String>>() {
public ObservableValue<String> call(CellDataFeatures<PersonType, String> p) {
// p.getValue() returns the PersonType instance for a particular TableView row
if (p.getValue() != null && p.getValue().getPerson() != null) {
return new SimpleStringProperty(p.getValue().getPerson().getFirstName());
} else {
return new SimpleStringProperty("<No TC firstname>");
}
}
});
}