How to use an output parameter in Java?

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Could someone please give me some sample code that uses an output parameter in function? I've tried to Google it but just found it just in functions. I'd like to use this output value in another function.

The code I am developing intended to be run in Android.

Java Practices->Output parameters, Define the output parameter(s) using either the out or inout option when you create the SQLJ stored procedure. Declare those parameters as Java arrays in the  A parameter is a value that you can pass to a method in Java. Then the method can use the parameter as though it were a local variable initialized with the value of the variable passed to it by the calling method. The guessing-game application has a method named getRandomNumber that returns a random number between 1 and 10:

Java does not support output parameters. You can use a return value, or pass in an object as a parameter and modify the object.

Using input and output parameters, All the applications that can access Relational databases (Java, Python, PHP etc.​), can access stored procedures. Stored procedures contain  Output parameters A method may occasionally need to use a parameter for its return value - what might be loosely called an "output parameter" or a "result parameter". The caller creates an output parameter object, and then passes it to a method which changes the state of the object (its data).

How to call a stored procedure that returns output parameters, using , Create and initialize a variable for the parameter of the correct Java data type (​see Example: Passing an INPUT-OUTPUT parameter using the Java OpenAPI​  Solution 2. Java does not support out parameter; all parameters are passed by value, but a parameter can be of mutable reference type, in this case, even though the instance of a parameter can not be modified referentially, the object itself can be modified inside the function and returned modified.

As a workaround a generic "ObjectHolder" can be used. See code example below.

The sample output is:

name: John Doe
dob:1953-12-17
name: Jim Miller
dob:1947-04-18

so the Person parameter has been modified since it's wrapped in the Holder which is passed by value - the generic param inside is a reference where the contents can be modified - so actually a different person is returned and the original stays as is.

/**
 * show work around for missing call by reference in java
 */
public class OutparamTest {

 /**
  * a test class to be used as parameter
  */
 public static class Person {
   public String name;
     public String dob;
     public void show() {
      System.out.println("name: "+name+"\ndob:"+dob);
   }
 }

 /**
  * ObjectHolder (Generic ParameterWrapper)
  */
 public static class ObjectHolder<T> {
    public ObjectHolder(T param) {
     this.param=param;
    }
    public T param;
 }

 /**
  * ObjectHolder is substitute for missing "out" parameter
  */
 public static void setPersonData(ObjectHolder<Person> personHolder,String name,String dob) {
    // Holder needs to be dereferenced to get access to content
    personHolder.param=new Person();
    personHolder.param.name=name;
    personHolder.param.dob=dob;
 } 

  /**
   * show how it works
   */
  public static void main(String args[]) {
    Person jim=new Person();
    jim.name="Jim Miller";
    jim.dob="1947-04-18";
    ObjectHolder<Person> testPersonHolder=new ObjectHolder(jim);
    // modify the testPersonHolder person content by actually creating and returning
    // a new Person in the "out parameter"
    setPersonData(testPersonHolder,"John Doe","1953-12-17");
    testPersonHolder.param.show();
    jim.show();
  }
}

Passing INPUT-OUTPUT parameters, The real question is "are functions with side-effects bad?" Providing a reference to an explicit mutable ("out") variable is no different than providing a Map that   CallableStatementParameterExample.java To get the output parameter data from stored procedure, you should first register the output data type with  java.sql.CallableStatement  as below code snippet, then you can get it’s value by it’s type. Full source code example. Above Example Console Output.

Wrap the value passed in different classes that might be helpful doing the trick, check below for more real example:

  class Ref<T>{

    T s;

    public void set(T value){
        s =  value;
    }

    public T get(){
        return s;
    }

    public Ref(T value) {
        s = value;
    }
}


class Out<T>{

    T s;

    public void set(T value){
        s =  value;
    }
    public T get(){
        return s;
    }

    public Out() {
    }
}

public static void doAndChangeRefs (Ref<String> str, Ref<Integer> i, Out<String> str2){
    //refs passed .. set value
    str.set("def");
    i.set(10);

    //out param passed as null .. instantiate and set 
    str2 = new Out<String>();
    str2.set("hello world");
}
public static void main(String args[]) {
        Ref<Integer>  iRef = new Ref<Integer>(11);
        Out<String> strOut = null; 
        doAndChangeRefs(new Ref<String>("test"), iRef, strOut);
        System.out.println(iRef.get());
        System.out.println(strOut.get());

    }

Is using "out" or "ref" parameters in Java methods to return extra , Java CORBA programmers need a general way to use both primitive types and reference types for output parameters in method calls on Java CORBA stubs. I have been developing Java/JDBC calls to stored procedures with some success. However I am stuck when an output parameter is an array of strings. I have been successful with scalar types as input and output parameters, as well as an array of strings as an input parameter. Here's the PL/SQL code I have:

Output Parameters, 'Output parameters. A method may occasionally need to use a parameter for its return value - what might be loosely called an "output parameter" or a "result  A SQL Server stored procedure that you can call is one that returns one or more OUT parameters, which are parameters that the stored procedure uses to return data back to the calling application. The Microsoft JDBC Driver for SQL Server provides the SQLServerCallableStatement class, which you can use to call this kind of stored procedure and process the data that it returns.

What is an example of output arguments in Java?, The value that you specify for the OUT parameter in the registerOutParameter method must be one of the JDBC data types contained in java.sql  For input parameters, use the in keyword to qualify the parameter. in is the default; Adaptive Server assumes an input parameter if you do not enter a parameter mode. For output parameters, use the out keyword. For parameters that can pass values both to and from the referenced Java method, use the inout keyword.

[Solved] how i can use out parameter in java, The java.lang.Math .pow () is used to calculate a number raise to the power of some other number. This function accepts two parameters and returns the value of first parameter raised to the second parameter. There are some special cases as listed below: If the second parameter is positive or negative zero then the result will be 1.0.

Comments
  • possible duplicate of Does Java have something like C#'s ref and out keywords?
  • I also need to get boolean return value. because some person values will be null and i wanna know whether there is any address or not. So I need to get back two values - boolean and string. That's why I wanna use passing by value.
  • Thanks a lot, polygen :)
  • is there no ref aswell then? Thats a major pain given that you can only have 1 class per file + the fact that there are no properties in java. It forces you to use extra classes but makes them cumbersome to write :(
  • @JonnyLeeds no need to have 1 class per file, you can use inner classes.
  • @JonnyLeeds one PUBLIC class per file I thought, plenty of private, package level, protected and indeed inner classes are ok.
  • Java is even worse than Basic!
  • see stackoverflow.com/questions/430479/… Answer: Simulating references with wrappers ...
  • You passed the object, but you didn't mutate it (which you couldn't anyway, since String is immutable). You tried to assign a new reference to it (oPerson = ...) which doesn't work (just like fArgNoWorkie), since Java is pass by value. Look at my code example and try to understand it.
  • In this case, instead of returning boolean, you can return a String, which is null if there's no match.
  • Hi, polygenelubricants, I tested it with oPerson. I got null. I edited my previous code above. Please check it again. Thank you.