Set default parameter in java

Java setting default values for methods in java

Output: Java Method Java does not support the concept of default parameter however, you can achieve this using Method overloading Using method overloading if you define method with no arguments along with parametrized methods. In this short tutorial, we’ll demonstrate the use of method overloading to simulate default parameters in Java.

Java Default Parameters Using Method Overloading

1. Overview

In this short tutorial, we’ll demonstrate the use of method overloading to simulate default parameters in Java.

Here, we say simulate because unlike certain other OOP languages (like C++ and Scala), the Java specification doesn’t support assigning a default value to a method parameter .

2. Example

As an example, let’s make some tea! First, we’ll need a Tea POJO:

Here, the name is a required field, as our Tea has to have a name at least.

Then, there cannot be any tea without tea powder. So, we’ll assume that the user wants a standard 1 tbsp teaPowder in their tea, if it’s not provided at invocation time. This then is our first default parameter .

The other optional parameters are milk (in ml), herbs (to add or not to add), and sugar (in tbsp). If any of their values are not provided, we assume the user doesn’t want them.

Let’s see how to achieve this in Java using method overloading :

public Tea(String name, int milk, boolean herbs, int sugar, int teaPowder) < this.name = name; this.milk = milk; this.herbs = herbs; this.sugar = sugar; this.teaPowder = teaPowder; >public Tea(String name, int milk, boolean herbs, int sugar) < this(name, milk, herbs, sugar, DEFAULT_TEA_POWDER); >public Tea(String name, int milk, boolean herbs) < this(name, milk, herbs, 0); >public Tea(String name, int milk) < this(name, milk, false); >public Tea(String name)

As is evident, here we’re using constructor chaining, a form of overloading to provide the method parameters with some default values.

Now let’s add a simple test to see this in action:

@Test public void whenTeaWithOnlyName_thenCreateDefaultTea()

3. Alternatives

There are other ways to achieve default parameter simulation in Java. Some of them are:

Here’s how we can make use of the third way of allowing null arguments in our example:

public Tea(String name, Integer milk, Boolean herbs, Integer sugar, Integer teaPowder)

4. Conclusion

In this article, we looked at using method overloading to simulate default parameters in Java.

While there are other ways to achieve the same, overloading is most clean and simple. As always, code is available over on GitHub.

Java function variables with default value [duplicate], I have some function in java and i want this function to have a parameter with a default value that is set to variable if no value sent,

Java Default Parameters

This tutorial introduces how to implement default parameters in Java.

A default parameter is used when no value is passed. It is helpful when we want to pass limited arguments while the method accepts multiple arguments. For example, a method accepts three arguments, but if we wish to pass only two arguments during the method call, then the Java compiler uses the default value of the third argument to avoid any compilation error.

Java does not support default parameters value, but we can achieve it using some built-in solutions such as var-args or method overloading. Let’s see some examples.

Default Parameters in Java

In this example, we use the method overloading approach to set the default parameter value. However, this is not a fine solution but can be used as an alternative. Notice, we pass 0 as the default value while calling the add() method.

This approach doesn’t work if we have two optional parameters of the same type, and any of them can be omitted.

public class SimpleTesting < int add(int a, int b) < return a+b; >int add(int a, int b, int c) < return a+b+c; >public static void main(String[] args) < SimpleTesting test = new SimpleTesting(); int val1 = 10; int val2 = 20; int result1 = test.add(val1, 0); int result2 = test.add(val1, 0, val2); System.out.println("resutl1 : "+ result1); System.out.println("resutl2 : "+result2); >> 

Set Default Parameters using var-args in Java

This is another approach where we use the variable args feature to set default parameters. The var-args allows passing a variable length of arguments of the same type. See the example below.

public class SimpleTesting< int add(int a, int. b) < int b2 = b.length>0?b[0]:0; return a+b2; > int add(int a, int b, int c) < return a+b+c; >public static void main(String[] args) < SimpleTesting test = new SimpleTesting(); int val1 = 10; int val2 = 20; int result1 = test.add(val1); int result2 = test.add(val1, 0, val2); System.out.println("resutl1 : "+ result1); System.out.println("resutl2 : "+result2); >> 

Sett Default Parameters as Empty String in Java

In the case of string parameters, we can set an empty string to the parameters; however, this string holds null as the default value. See the example below.

public class SimpleTesting < String defaulPara(int a, String str1, String str2) < return str1+str2+a; >public static void main(String[] args) < SimpleTesting test = new SimpleTesting(); int val1 = 10; String result1 = test.defaulPara(val1,"","second"); String result2 = test.defaulPara(val1,"first",""); System.out.println("resutl1 : "+ result1); System.out.println("resutl2 : "+result2); >> 

resutl1 : second10 resutl2 : first10 

Set Default Parameters using var-args with any number of arguments in Java

In the case of var-args, we are free to provide any number of arguments while calling the method. So, if you want to provide only limited arguments, then it will work fine. See the example below.

public class SimpleTesting < int defaulPara(int. a) < int sum = 0; for (int i : a) < sum+=i; >return sum; > public static void main(String[] args) < SimpleTesting test = new SimpleTesting(); int val1 = 10; int val2 = 20; int result1 = test.defaulPara(); int result2 = test.defaulPara(val1); int result3 = test.defaulPara(val1, val2); System.out.println("resutl1 : "+ result1); System.out.println("resutl2 : "+result2); System.out.println("resutl3 : "+result3); >> 

resutl1 : 0 resutl2 : 10 resutl3 : 30 

Java Method

Constructors with default values of parameters, No it doesn’t. Java doesn’t support default arguments in any function; constructors included. What

Does Java support default parameter values for a method?

Java does not support the concept of default parameter however, you can achieve this using

Method overloading

Using method overloading if you define method with no arguments along with parametrized methods. Then you can call a method with zero arguments.

Variable arguments

In Java methods parameters accept arguments with three dots. These are known as variable arguments. Once you use variable arguments as a parameter method, while calling you can pass as many number of arguments to this method (variable number of arguments) or, you can simply call this method without passing any arguments.

Example

public class Sample < void demoMethod(String. args) < for (String arg : args) < System.out.println(arg); >> public static void main(String args[] ) < new Sample().demoMethod("ram", "rahim", "robert"); new Sample().demoMethod("krishna", "kasyap"); new Sample().demoMethod(); >>

Output

ram rahim robert krishna kasyap

What is the default value of a local variable in Java?, When the program control enters the methods, code blocks, constructors, etc. then the local variables are created and when the program control

Is it possible to declare default argument in Java in String? [duplicate]

No, the way you would normally do this is overload the method like so:

public void test() < test("exampleText"); >public void test(String name)

No, it is not. However, the following is possible:

public void test() < test("exampleText"); >public void test(String name) < //logic here >

Java — Variable Types, Default values are same as instance variables. For numbers, the default value is 0; for Booleans, it is false; and for object references, it is null. Values can

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Java Default Parameters

1. Default Parameters in Java
2. Set Default Parameters using var-args in Java
3. Set Default Parameters as Empty String in Java
4. Set Default Parameters using var-args with any number of arguments in Java

This tutorial introduces how to implement default parameters in Java.

A default parameter is used when no value is passed. It is helpful when we want to pass limited arguments while the method accepts multiple arguments. For example, a method accepts three arguments, but if we wish to pass only two arguments during the method call, then the Java compiler uses the default value of the third argument to avoid any compilation error.

Java does not support default parameters value, but we can achieve it using some built-in solutions such as var-args or method overloading. Let’s see some examples.

Default Parameters in Java

In this example, we use the method overloading approach to set the default parameter value. However, this is not a fine solution but can be used as an alternative. Notice, we pass 0 as the default value while calling the add() method.

This approach doesn’t work if we have two optional parameters of the same type, and any of them can be omitted.

public class SimpleTesting  int add(int a, int b)   return a+b;  >  int add(int a, int b, int c)   return a+b+c;  >  public static void main(String[] args)   SimpleTesting test = new SimpleTesting();  int val1 = 10;  int val2 = 20;  int result1 = test.add(val1, 0);  int result2 = test.add(val1, 0, val2);  System.out.println("resutl1 : "+ result1);  System.out.println("resutl2 : "+result2);  > > 

Set Default Parameters using var-args in Java

This is another approach where we use the variable args feature to set default parameters. The var-args allows passing a variable length of arguments of the same type. See the example below.

public class SimpleTesting  int add(int a, int. b)   int b2 = b.length>0?b[0]:0;  return a+b2;  >  int add(int a, int b, int c)   return a+b+c;  >  public static void main(String[] args)   SimpleTesting test = new SimpleTesting();  int val1 = 10;  int val2 = 20;  int result1 = test.add(val1);  int result2 = test.add(val1, 0, val2);  System.out.println("resutl1 : "+ result1);  System.out.println("resutl2 : "+result2);  > > 

Set Default Parameters as Empty String in Java

In the case of string parameters, we can set an empty string to the parameters; however, this string holds null as the default value. See the example below.

public class SimpleTesting  String defaulPara(int a, String str1, String str2)   return str1+str2+a;  >  public static void main(String[] args)   SimpleTesting test = new SimpleTesting();  int val1 = 10;  String result1 = test.defaulPara(val1,"","second");  String result2 = test.defaulPara(val1,"first","");  System.out.println("resutl1 : "+ result1);  System.out.println("resutl2 : "+result2);  > > 

resutl1 : second10 resutl2 : first10 

Set Default Parameters using var-args with any number of arguments in Java

In the case of var-args, we are free to provide any number of arguments while calling the method. So, if you want to provide only limited arguments, then it will work fine. See the example below.

public class SimpleTesting  int defaulPara(int. a)   int sum = 0;  for (int i : a)   sum+=i;  >  return sum;  >  public static void main(String[] args)   SimpleTesting test = new SimpleTesting();  int val1 = 10;  int val2 = 20;  int result1 = test.defaulPara();  int result2 = test.defaulPara(val1);  int result3 = test.defaulPara(val1, val2);  System.out.println("resutl1 : "+ result1);  System.out.println("resutl2 : "+result2);  System.out.println("resutl3 : "+result3);  > > 

resutl1 : 0 resutl2 : 10 resutl3 : 30 

Related Article — Java Method

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