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How to pass a Default and Optional Parameter into a function like a python in the Java

I am trying to migrate the python library into the java native script but I facing extreme complexity with the parameters while migration.
Here the code I need to migrate the python method with the default & optional parameters with different datatypes into the java method:
def connect_network(self,
bssid=None,
proto="http",
check_redirect_code=True,
redirect_code='302',
portal_url=None,
subscriber_portal='scg',
expect_href_list_zd_sp='google',
check_user_block=False,
redirect_url='',
tnc_content="",
path="/tmp/"):
pass
Here is my example code which I tried in java equivalent:
public class LinuxClientUtils {
public void DefaultNameParameter1(HashMap<Integer, String> params){
System.out.Println(params.toString());
}
public void DefaultNameParameter2(Map.Entry<String, String>... params){
System.out.Println(params.toString());
}
public void DefaultNameParameter3(Optional<String> name, Optional<String> age){
System.out.Println(name.toString());
}
}
I will import that Java library in the robot framework and call the method like this,
*** Settings ***
Library test.LinuxClientUtils
*** Test Cases ***
Testing
[tags] service
[Documentation] Add Network
Default Name Parameter3 req_network_id=89
Still, None of the methods didn't work.
I have tried few Methods from the following URLs Link-1
Link-2 But I am unable to figure it out from those links.
I'm new to JAVA programming and haven't been able to fix this one. Any help would be great, thanks.

Create a new class for a parameter object. It will have each of the parameters as a field.
The constructor of this parameter class has no parameters. Instead, each field has a default value. (null and false are automatically assigned by default for object and boolean fields, anyway.)
Your function will just take a parameter object as a single parameter.
public class A {
static class ParameterObject {
public ParameterObject(){
//empty
}
private int x;
private boolean b;
private String s;
public int getX() {
return x;
}
public void setX(int x) {
this.x = x;
}
public boolean isB() {
return b;
}
public void setB(boolean b) {
this.b = b;
}
public String getS() {
return s;
}
public void setS(String s) {
this.s = s;
}
}
public static void f(ParameterObject o){
//Do something with object
}
public static void main(String[] args) {
ParameterObject paramObj=new ParameterObject();
paramObj.setX(10);
f(paramObj);
}
}

How to throw exception for a local object method call?

MyCode:
class LocalClass{
public getNumber(){
retunr 5;
}
}
class AnotherLocalClass{
public static getNumber(){
retunr 10;
}
}
public class A{
public int methodAa(Boolean flag, int paramValue){
return methodA(flag, paramValue);
}
private int methodA(Boolean flag, int paramValue){
int returnValue = 0;
try{
if(flag){
LocalClass localVariable = new LocalClass();
returnValue = localVariable.getNumber() + paramValue;
} else{
returnValue = AnotherLocalClass.getNumber() + paramValue;
}
return returnValue;
}catch(Exception e){
e.printStackTrace();
return 0;
}
}
}
public class ATest{
#InjectMocks
A a;
public void methodATest(){
//need help to write here
}
}
LocalClass and AnotherLocalClass are classes that contains a method that returns a value.
getNumber in AnotherLocalClass is a static method.
Class A is the main class for which I am writing ATest class.
I can only write code in methodATest. And cannot change anything in LocalClass, AnotherLocalClass or class A.
I want to write methodATest such that methodA throws an exception.
My mockito version is 1.19.10 and it cannot be changed.
And also I cannot use PowerMockito or any other new dependency.

What exceptions do you expected to occur on your code? Which parameter values will cause the exceptions? In those cases, what is the return value that you're expecting?
When you get the answers for those questions, then you gonna have to set the conditions for the exception to happen. Then your code is gonna look something like this:
public class ATest{
A a = new A();
#Test
public void methodATest(){
Boolean flag = ?;
int paramValue = ?;
int expectedReturnValue = ?;
int returnValue = a.methodAa(flag, paramValue);
assertEquals(expectedReturnValue, returnValue);
}
}
Look out for the mock method. We usually use it when we need to set a class that we don't exactly want it to run it's methods, so we mock then to return something that we need for our test to work.
You can learn more about tests with this tutorial: https://www.vogella.com/tutorials/JUnit/article.html#junittesting
----[Edit]----
If you wanted to mock the LocalClass, you were gonna need to do something like this:
#PrepareForTest({LocalClass.class, A.class})
#RunWith(PowerMockRunner.class)
public class ATest{
A a = new A();
#Test
public void methodATest(){
PowerMockito.mockStatic(LocalClass.class);
PowerMockito.when(LocalClass.getNumber()).thenThrow(new Exception());
...
}
}
But, the getNumber() method should be static for it to work.
And, since you can not use PowerMockito, it's not possible to mock the class.
----[Edit]----
#PrepareForTest({AnotherLocalClass.class, A.class})
#RunWith(PowerMockRunner.class)
public class ATest{
A a = new A();
#Test
public void methodATest(){
PowerMockito.mockStatic(AnotherLocalClass.class);
PowerMockito.when(AnotherLocalClass.getNumber()).thenThrow(new Exception());
a.methodAa(...);
...
}
}
But again, since static method belongs to the class, there is no way in Mockito to mock static methods.

How to add to array in main?

I have created an array which I wanted to control from main. My code runs, but I don't know how to add integers to the array from the main class. Also as each ConcreteSubject has its own storage array, how would i change this to store them all in the same array?
public class ConcreteSubject extends AbstractSpy
{
private AbstractSpy[] spies = new AbstractSpy[10];
private int i = 0;
public void addSpy(AbstractSpy s) {
if (i < spies.length) {
spies[i] = s;
System.out.println("spy added at index " + i);
i++;
}
}
}
public class TestClass
{
public static void main(String[] args) {
ConcreteSubject cs = new ConcreteSubject();
AbstractSpy spies = new AbstractSpy() {
#Override
public void addSpy(AbstractSpy spies) {
}
};
cs.addSpy(cs);
spies.addSpy(spies);
}
}

It seems like your program logic is a little borked. This bit in particular doesn't make much sense:
***AbstractSpy spies = new AbstractSpy() {
#Override
public void addSpy(AbstractSpy spies) {
}
};
cs.addSpy(cs);
***spies.addSpy(spies);
What you're doing is creating TWO AbstractSpy instances, one named cs and one named spies. On that last line you're adding spies to itself! That doesn't help you at all.
Note that AbstractSpy is the most granular unit in your setup - it shouldn't have an addSpy() method and its own internal array, it should be the thing that's added to something else's array!
Here's the same code, but cleaned up a bit:
public abstract class AbstractSpy { }
public class ConcreteSpy extends AbstractSpy { }
public class ConcreteSubject {
private AbstractSpy[] spies = new AbstractSpy[10];
private int i = 0;
public void addSpy(AbstractSpy spy) {
if (i < spies.length)
{
spies[i] = spy;
System.out.println("spy added at index " + i);
i++;
}
}
}
public class TestClass {
public static void main(String[] args) {
ConcreteSubject cs = new ConcreteSubject();
AbstractSpy spy = new ConcreteSpy();
cs.addSpy(spy);
}
}
The big difference here is that ConcreteSpy is an implementation of AbstractSpy that you can add to your ConcreteSubject's array of spies. I think you might have been confused by Java's insistence that you can't create an instance of an abstract class on its own unless you supply an anonymous class that inherits from the abstract class.

Initialize Empty HashMap

I come from writing a lot of JavaScript, so bear with me.
I've got 3 HashMaps, which i reference in a method in a different class. My code (very simply) looks like so:
public class MainClass {
private HashMap<String,Nation> randomHashMap = new HashMap<String,Nation>();
DifferentClass d = new DifferentClass(this);
} //with getters/setters
public class DifferentClass {
private MainClass mc;
public void randomMethod() {
System.out.println("randomHashMap is " + (mc.getRandomHashMap() == null));
} //returns null
public DifferentClass(MainClass c) {
this.mc = c;
}
}
However, when I call them in my other method, they're null.
How do I create a new, empty HashMap?

You need to initialize your MainClass mc variable before using it in the DifferentClass#randomMethod method. Also, make sure you're using the mc variable instead of the MainClass.getRandomHashMap() method (by your actual code, we don't know how it behaves). Your code will look like this:
public class DifferentClass {
private MainClass mc = new MainClass();
public void randomMethod() {
//assuming getRandomHashMap is the getter of randomHashMap attribute (and non static)
System.out.println("randomHashMap is " + (mc.getRandomHashMap() == null));
}
}
public class MainClass {
private HashMap<String,Nation> randomHashMap = new HashMap<String,Nation>();
DifferentClass d = new DifferentClass(this);
public HashMap<String,Nation> getRandomHashMap() {
return this.randomHashMap;
}
} //with getters/setters

The code you posted is in fact perfectly all right as far as field initialization. I made an SSCCE from it with minimal intervention:
class Nation{}
public class MainClass {
private HashMap<String,Nation> randomHashMap = new HashMap<String,Nation>();
DifferentClass d = new DifferentClass(this);
public Object getRandomHashMap() {
return randomHashMap;
}
public static void main(String[] args) {
new MainClass().d.randomMethod();
}
} //with getters/setters
class DifferentClass {
private MainClass mc;
public void randomMethod() {
System.out.println("randomHashMap is " + (mc.getRandomHashMap() == null));
} //returns null
public DifferentClass(MainClass c) {
this.mc = c;
}
}
and it prints
randomHashMap is false
which proves that randomHashMap is indeed non-null.

Java and avoid if statements for objects with similar methods

I have 2 classes e.g. A and B.
These classes have a couple of getter/setter methods with the same name.
Now in the code I do the following:
if(obj.getClassName().equals(A.class.getName())){
A a = (A) obj;
String result = a.getInfo();
}
else if(obj.getClassName().equals(B.class.getName())){
B a = (B) obj;
String result = a.getInfo();
}
I was wondering if there is a way to call the getInfo avoiding the if statements.
Note: I can not refactor the classes to use inheritence or something else.
I was just interested if there is a trick in java to avoid the if statements.

Unless you want to use reflection, no. Java treats two types which happen to declare the same method (getInfo()) as entirely separate, with entirely separate methods.
If you've got commonality, you should be using a common superclass or a common interface that both of them inherit. You've tagged the question "design-patterns" - the pattern is to use the tools that the language provides to show commonality.
As Eng.Fouad shows, using instanceof is simpler anyway - and better, as it means your code will still work with subclasses of A or B.
You can isolate this ugliness, of course, by putting it in a single place - either with a facade class which can be constructed from either an A or a B, or by having a single method which performs this check, and then calling that from multiple places.

If you can't use inheritance and want to avoid if statements (even using instanceof)... well... the best you can do is wrap the check, cast and call in a function to avoid code duplication... otherwise there's no way to do this.

You need reflection. here is my complete example.
Class A
package a;
public class A {
String info;
public String getInfo() {
System.out.println("A getInfo");
return info;
}
public void setInfo(String info) {
this.info = info;
}
}
Class B
package a;
public class B {
String info;
public String getInfo() {
System.out.println("B getInfo");
return info;
}
public void setInfo(String info) {
this.info = info;
}
}
Test Class
package a;
import java.lang.reflect.Method;
public class TestAB {
public static void main(String[] args) {
A a= new A();
doSth(a);
}
private static void doSth(Object obj) {
Class c = obj.getClass();
Method m;
try {
m = c.getMethod("getInfo", new Class[] { });
String result = (String) m.invoke(obj);
} catch (Exception e) {
e.printStackTrace();
}
}
}
See this line :
Class c = obj.getClass();
and
m = c.getMethod("getInfo", new Class[] { });
and
String result = (String) m.invoke(obj);
There is no if statements

If obj is declared as either A or B, you can use overloaded methods. (A good argument for type safety.) Here's a test that illustrates this:
import static org.junit.Assert.*;
import org.junit.Test;
public class FooTest {
class A {
public String getInfo() {
return "A";
}
}
class B {
public String getInfo() {
return "B";
}
}
public String doBarFor(A a) {
return a.getInfo();
}
public String doBarFor(B b) {
return b.getInfo();
}
public String doBarFor(Object obj) {
throw new UnsupportedOperationException();
}
#Test
public void shouldDoBarForA() {
A a = new A();
assertEquals("A", doBarFor(a));
}
#Test
public void shouldDoBarForB() {
B b = new B();
assertEquals("B", doBarFor(b));
}
#Test(expected = UnsupportedOperationException.class)
public void shouldFailIfDeclaredAsObject() {
Object a = new A();
assertEquals("A", doBarFor(a)); // exception thrown
}
}

How about:
String result = null;
if(obj instanceof A)
{
result = ((A) obj).getInfo();
}
else if(obj instanceof B)
{
result = ((B) obj).getInfo();
}

Refer to : this tutorial if this is what you were trying to achieve.

If obj is an Object, you'll need to check. If you don't want to use an if-statement, you can try just casting and catch the exception:
String result = null;
try {
result = ((A)obj).getInfo();
}
catch(ClassCastException e1) {
try {
result = ((B)obj).getInfo();
}
catch(ClassCastException e2) {
// do something else
}
}
Another thing you can do is make both classes implement an Interface then check for just that Interface, something like:
public interface HasInfo
{
public String getInfo();
}
Then add implements HasInfo in the class definition for A and B. Then you can just check (or cast) to HasInfo.

In Java you can use a dot as a scope resolution operator with static methods. Try something like this:
String a_info = A.getInfo();
String b_info = B.getInfo();
With objects, if two interfaces really have the same method with the same parameters and the same return type, why must they be treated differently? Take a look here for some more insight into the problem.
Good luck.