How to do nothing in java

Java do nothing

Secondly, as others pointed out, you don’t have to have that empty block, unless you need to say something about the condition or possibly leave space to handle it. ,The NULL;-statement doesn’t tell anything, or does it?,The correct way of handling this is to remove the unecessary else if or to rewrite your conditions instead of having a marker for an empty block.,If you really really want to communicate why you did not handle a certain condition, write a comment above the method or the statement.

if (cond1) < . >else if (cond2) < NULL; >else

if (cond1) < . >else if (cond2) < >else

So this makes perfect sense:

if (cond1) < . >else if (cond2) < //cond2 is not handled, because 2 is the smallest prime number >else

if (cond1) < . >else if (cond2) < //TODO: investigate whether/how this condition needs to be handled >else

Answer by Andrew Moon

I’m working on A Day at the Supermarket 1.4 and curiously, I can make the “if” statement work just fine, but the trouble I’m having is how to make the “else:” statement do nothing. I tried various things such as:,else: return “nothing.”,For the line after “else:” use the “pass” no-op python keyword,(The indentation gets lost when I submit the edit. The preview looks fine.)

It looks a little bit like this

Answer by Enzo Guerrero

I have an if statement here and I don’t know how to get Java to do nothing if the value is more than 0. I get the error message I have programmed no matter what value I enter!,This is the entire program -,When I test it and enter the value «1» it still says that negative values are not permitted because of that if statement I created. The program does work as intended in that it outputs the word corresponding to numbers from 1-9, but it still outputs like this -,If i understood correctly you want to print an Error if number < 0 and do nothing if number >= 0.

Well, you don’t need the else clause then. You can simply do:

Answer by Aubrielle Vo

What is the equivalent to Python’s pass in Java? I realize that I could use continue or not complete the body of a statement to achieve that effect, but I like having a pass statement.,but when a method is supposed to return a value, while pass may still work in Python, one will stuck with compilation problem when not returning a value.,I personally use: throw new java.lang.UnsupportedOperationException(«Not supported yet.»); — this is searchable, alerts you that the method is not implemented and is compatible with the strict return types.,There is no (strict) equivalent since in java you have to specify the return type for the method in its declaration which is then checked against a computed type of the following the return statement. So for methods that have a return type — neither semicollon nor leaving empty braces will work;

If you want something noticeable, you can use

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Java do nothing

What is the equivalent to Python’s pass in Java? I realize that I could use continue or not complete the body of a statement to achieve that effect, but I like having a pass statement.

Java Solutions

Solution 1 — Java

Just use a semi-colon ; , it has the same effect.

Solution 2 — Java

If you want something noticeable, you can use

This will allow you to have something that a reader can recognize or that can be searched for.

Solution 3 — Java

; is the empty statement. Usually, you don’t need it — you can just put nothing in the brackets for an empty loop — but it can be useful.

Solution 4 — Java

I normally use something like:

It’s useful to be able to have a line of code which does nothing when debugging. You can put a breakpoint on that line, which is especially useful if it would usually be an empty block of code (e.g. empty catch block etc), as putting a breakpoint on an empty line can create confusion about where the breakpoint is actually set.

Solution 5 — Java

There is no (strict) equivalent since in java you have to specify the return type for the method in its declaration which is then checked against a computed type of the following the return statement. So for methods that have a return type — neither semicollon nor leaving empty braces will work;

I personally use: throw new java.lang.UnsupportedOperationException(«Not supported yet.»); — this is searchable, alerts you that the method is not implemented and is compatible with the strict return types.

Solution 6 — Java

I feel, there is no construct in Java identical to pass in Python. This is mostly because Java is a statically typed language where as Python is a dynamically typed language. More so when you are defining a method / function. In that context, the provided answers are valid / correct only for a method that returns void.

For example for a Python function

def function_returns_void: pass 

you can have a Java method

public void function_returns_void()<> 

public void function_returns_void() 

but when a method is supposed to return a value, while pass may still work in Python, one will stuck with compilation problem when not returning a value.

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Java do nothing in Java

This will allow you to have something that a reader can recognize or that can be searched for.

; is the empty statement. Usually, you don’t need it — you can just put nothing in the brackets for an empty loop — but it can be useful.

I normally use something like:

It’s useful to be able to have a line of code which does nothing when debugging. You can put a breakpoint on that line, which is especially useful if it would usually be an empty block of code (e.g. empty catch block etc), as putting a breakpoint on an empty line can create confusion about where the breakpoint is actually set.

There is no (strict) equivalent since in java you have to specify the return type for the method in its declaration which is then checked against a computed type of the following the return statement. So for methods that have a return type — neither semicollon nor leaving empty braces will work;

I personally use: throw new java.lang.UnsupportedOperationException(«Not supported yet.»); — this is searchable, alerts you that the method is not implemented and is compatible with the strict return types.

I feel, there is no construct in Java identical to pass in Python. This is mostly because Java is a statically typed language where as Python is a dynamically typed language. More so when you are defining a method / function. In that context, the provided answers are valid / correct only for a method that returns void.

For example for a Python function

def function_returns_void: pass 

you can have a Java method

public void function_returns_void()<> 

public void function_returns_void()

but when a method is supposed to return a value, while pass may still work in Python, one will stuck with compilation problem when not returning a value.

Related

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Return Nothing From a Function in Java

1. Return Nothing in an Integer Function in Java
2. Return Nothing in a String Function in Java
3. Return Nothing in Any Object Function in Java

This tutorial introduces how to return nothing in function in Java.

Every function that has a return type in its signature must return a value of the same type, else the compile will generate an error, and the code will not execute. It means a return value is a value that is returned to the caller function, and if we wish to return nothing, then we will have to return some default value.

For example, we can return null for String type and 0 for the integer value to handle such a situation. Let’s understand with some examples.

Return Nothing in an Integer Function in Java

In this example, we have a static method that returns an integer, but we want to return nothing in a special case, then we return 0 only. Although there is nothing in integer to return, we can do this to achieve our objective.

public class SimpleTesting  public static void main(String[] args)  int result = getMax(12, 12);  System.out.println(result);  >   public static int getMax(int a, int b)   if(a>b)   return a;  >  else if (b>a)   return b;  >  return 0; // similar to nothing in int  > > 

Return Nothing in a String Function in Java

In this example, we have a static method that returns a String, but we want to return nothing in a special case, then we return null only. Although there is nothing like nothing in String to return, we can achieve our objective.

public class SimpleTesting  public static void main(String[] args)  String result = getMax("rohan", "sohan");  System.out.println("result "+result);  result = getMax("sohan", "sohan");  System.out.println("result "+result);  >   public static String getMax(String a, String b)   if(a.compareTo(b)>0)   return a;  >  else if (a.compareTo(b)0)   return b;  >  return null; // similar to nothing in String  > > 

Return Nothing in Any Object Function in Java

In this example, we have a static method that returns an integer object, but we want to return nothing in a special case, then we return null only as null is a default value for objects in Java. Although there is nothing like nothing in objects to return, we can achieve our objective.

We can use this for any other object as well. See the example below.

import java.util.ArrayList; import java.util.Collections; import java.util.List;  public class SimpleTesting  public static void main(String[] args)  ListInteger> list = new ArrayList<>();  list.add(23);  list.add(32);  list.add(33);  System.out.println(list);  Integer result = getMax(list);  System.out.println("result "+result);  >   public static Integer getMax(ListInteger> list)   if(Collections.max(list)>100)   return 100;  >  else if (Collections.max(list)50)   return Collections.max(list);  >  return null; // similar to nothing in Integer object  > > 

Related Article — Java Function

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JUnit doNothing Example

In this tutorial we shall show users the usage of doNothing method. This method is basically resides inside the Mockito framework and is not a part of the JUnit.

1. Introduction

Many developers thought about the ways to test methods but do nothing about this. They might want to run the method only for the purpose of some other things that are related to that method. But directly there is no test required on that method itself.

In order to help you master unit testing with JUnit, we have compiled a kick-ass guide with all the major JUnit features and use cases! Besides studying them online you may download the eBook in PDF format!

Thank you!

Use doNothing() for setting void methods to do nothing.

Note: Beware that void methods on mocks do nothing by default. There are rare situations when doNothing() comes handy. Sometimes is used in void return methods or to a method that does not have side effects, or is not related to the unit testing you are doing. This is how definition of the doNothing() method looks like.

public static Stubber doNothing()

2. Project Dependencies

3. JUnit doNothing Example

Let’s take a small set of examples that use the doNothing() method. Examples below are taken from the Mockito framework. We need to add the following configurations to the project if we are using Maven.

 junit junit 4.12  org.mockito mockito-core 2.7.12  

Stubbing consecutive calls on a void method:

. doNothing().doThrow(new RuntimeException()).when(mock).someVoidMethod(); //does nothing the first time: mock.someVoidMethod(); //throws RuntimeException the next time: mock.someVoidMethod(); .

Here calling the someVoidMethod() first it will do nothing. But on the consecutive call it will throw an error. When you spy real objects and you want the void method to do nothing:

. List list = new LinkedList(); List spy = spy(list); //let's make clear() do nothing doNothing().when(spy).clear(); spy.add("one"); //clear() does nothing, so the list still contains "one" spy.clear(); .

In this example we are simply spying on the real object and we are doing some changes on that. But when we use doNothing() method, the real object will not change.

4. Conclusion

It is clear from this example that doNothing() is nothing but a method that will do nothing when applied to something. There are very limited uses of it as we have seen above. By default, all void methods in Mockito do nothing.

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