Variable Capture
Description
A lambda expression can access final local variables or local-non-final-initialized-only-once variables.
Example
The following code shows that we can access and use the final local variables.
import java.util.function.Function;
/*w ww . j a v a 2s. c o m*/
public class Main {
public static void main(String[] argv) {
final String x = "Hello";
Function<String,String> func1 = y -> {return y + " "+ x ;};
System.out.println(func1.apply("java2s.com"));
}
}
The code above generates the following result.
Example 2
The following code has a variable x which is not final but only initialized once. We can still use it in the lambda expression.
import java.util.function.Function;
//from w ww. j av a 2s . c o m
public class Main {
public static void main(String[] argv) {
String x = "Hello";
Function<String,String> func1 = y -> {return y + " "+ x ;};
System.out.println(func1.apply("java2s.com"));
}
}
The code above generates the following result.
Example 3
The following code shows that we cannot change the value defined outside lambda expression.
import java.util.function.Function;
//from w w w. j a va 2s. co m
public class Main {
public static void main(String[] argv) {
String x = "Hello";
Function<String,String> func1 = y -> {/*x="a";*/ return y + " "+ x ;};
System.out.println(func1.apply("java2s.com"));
}
}
The code above generates the following result.
Example 4
We can change the non-local variable in lambda expression.
import java.util.function.Function;
//from w w w. j av a 2 s . co m
public class Main {
static String x = "Hello";
public static void main(String[] argv) {
Function<String,String> func1 = y -> {x="a"; return y + " "+ x ;};
System.out.println(func1.apply("java2s.com"));
}
}
The code above generates the following result.
