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https://github.com/mrwilbroad/introduction-to-java

Introduction to Java programming Language
https://github.com/mrwilbroad/introduction-to-java

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Introduction to Java programming Language

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README

        

- CONNECT JAVA WITH POSTGRESQL DATABASE

1. Retrieve data
2. Save data
- ALL operation through PreparedStatement
```java
public List all()
{
String Sql = "SELECT * FROM employee;";
List staffs = new ArrayList<>();

try(
Connection connection = this.connection();
Statement statement = connection.createStatement();
ResultSet result = statement.executeQuery(Sql);
){

while (result.next()){
Staff staff = new Staff();

staff.id = result.getInt("id");
staff.first_name = result.getString("first_name");
staff.last_name = result.getString("last_name");
staff.email = result.getString("email");
staff.gender = Gender.valueOf(result.getString("gender"));
staff.age = result.getInt("age");
staff.salary = result.getDouble("salary");
staff.region = result.getString("region");
staff.department = result.getString("department");
staffs.add(staff);
}

}catch (SQLException e){
this.Close();
throw new RuntimeException(e);

}

return staffs;
}
```

- Good way to use Stream to handle data in multiple way
```java
public void showStaffs (){
Staff staff = new Staff();

List staffs = staff.all();
// all staffs
staffs.forEach(staf -> System.out.printf("%s%n%n",staf.getStaffInfo()));

List FilteredStaff = staffs.stream()
.filter(thisStaff -> thisStaff.getAge() < 40)
.toList();

// staffs with age below 40
FilteredStaff.forEach(staf -> System.out.printf("%s%n%n",staf.getStaffInfo()));

}
```