Properties forEach(BiConsumer) method in Java with Examples
Last Updated :
23 May, 2019
The forEach(BiConsumer) method of Properties class perform the BiConsumer operation on each entry of hashtable until all entries have been processed or the action throws an exception. The BiConsumer operation is a function operation of key-value pair of hashtable performed in the order of iteration. Method traverses each element of Hashtable until all elements have been processed by the method or an exception occurs. Exceptions thrown by the Operation are passed to the caller.
Syntax:
public void forEach(BiConsumer action)
Parameters: This method accepts a parameter action of BiConsumer type that represents what action are to be performed on the properties elements.
Returns: This method do not return anything.
Exceptions: This method throws NullPointerException if the action is null.
Below programs illustrate the forEach(BiConsumer) method:
Program 1:
import java.util.*;
public class GFG {
public static void main(String[] args)
{
Properties properties = new Properties();
properties.put( "Pen" , 10 );
properties.put( "Book" , 500 );
properties.put( "Clothes" , 400 );
properties.put( "Mobile" , 5000 );
System.out.println( "Properties 1: "
+ properties.toString());
properties.forEach((k, v) -> {
v = ( int )v + 100 ;
properties.replace(k, v);
});
properties.forEach(
(k, v) -> System.out.println( "Key : " + k + ", Value : " + v));
}
}
|
Output:
Properties 1: {Book=500, Mobile=5000, Pen=10, Clothes=400}
Key : Clothes, Value : 500
Key : Mobile, Value : 5100
Key : Pen, Value : 110
Key : Book, Value : 600
Program 2: To show NullPointerException
import java.util.*;
public class GFG {
public static void main(String[] args)
{
Properties properties = new Properties();
properties.put( 1 , "100RS" );
properties.put( 2 , "500RS" );
properties.put( 3 , "1000RS" );
System.out.println( "Current Properties: "
+ properties.toString());
try {
properties.forEach((k, v) -> {
v = (String)v + "100" ;
properties.put( null , v);
});
}
catch (Exception e) {
System.out.println( "Exception: " + e);
}
}
}
|
Output:
Current Properties: {3=1000RS, 2=500RS, 1=100RS}
Exception: java.lang.NullPointerException
References: https://docs.oracle.com/javase/9/docs/api/java/util/Properties.html#forEach-java.util.function.BiConsumer-
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