Java 8 Lambda Expressions with Examples

Java 8 Lambda Expressions with Examples

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Lambda expressions in Java 8 are essentially unnamed functions without return types or access modifiers. They’re also known as anonymous functions or closures. Let’s explore Java 8 lambda expressions with examples.

Example 1:

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public void m() {
    System.out.println("Hello world");
}

Can be express as:

Java 8 Lambda Expressions with Examples

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() -> {
    System.out.println("Hello world");  
}
 
//or
 
() ->  System.out.println("Hello world");

Example 2:

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public void m1(int i, int j) {
    System.out.println(i + j);
}

Can be expressed as:

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(int i, int j) -> {
    System.out.println(i + j);
}

If the type of the parameters can be inferred by the compiler based on the context, we can omit the types. The above lambda expression can be rewritten as:

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(i, j) ->  System.out.println(i+j);

Example 3:

Consider the following transformation:

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public String str(String s) {
    return s;
}

can be expressed as:

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(String s) -> return s;

or

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(String s) -> s;

Conclusion:

  1. A lambda expression can have zero or more arguments (parameters).
  • Example:
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() -> System.out.println("Hello world");
(int i) -> System.out.println(i);
(int i, int j) -> System.out.println(i + j);

2. We can specify the type of the parameter. If the compiler can infer the type based on the context, then we can omit the type.

Example:

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(int a, int b) -> System.out.println(a + b);
(a, b) -> System.out.println(a + b);

3. If multiple parameters are present, they should be separated by a comma (,).

4. If no parameters are present, we use empty parentheses [ like () ].

Example:

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() -> System.out.println("hello");

5. If only one parameter is present and if the compiler can infer the type, then we can omit the type and parentheses.

  • Example:
Java 8 Lambda Expressions with Examples

6. Similar to a method body, a lambda expression body can contain multiple statements. If there are multiple statements, they should be enclosed in curly braces {}. If there is only one statement, curly braces are optional.

7. Once we write a lambda expression, we can call that expression just like a method. To do this, functional interfaces are required.

This covers the basics of lambda expressions using in java 8 with relevant examples.

For more information, follow this link: Oracle’s guide on lambda expressions.

Here is the link for the Java 8 quiz:
Click here

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