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Java 8 - forEach method example with Map
forEach is a new method introduced in Java 8 to iterate over collections. Here is an example on forEach method
to iterate over Map.
package com.java2novice.java8;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
public class ForEachMapEx {
public static void main(String a[]) {
Map<String, String> countryMap = new HashMap<>();
countryMap.put("India", "Delhi");
countryMap.put("USA", "Washington, D.C.");
countryMap.put("Japan", "Tokyo");
countryMap.put("Canada", "Ottawa");
// iterate through Map normal way
ForEachMapEx.iterateMap(countryMap);
// iterate through Map using forEach method
ForEachMapEx.iterateMapUsingForEach(countryMap);
}
public static void iterateMap(Map<String, String> countryMap) {
System.out.println("<----------Iterating in normal way------------->");
for(Entry<String, String> entry:countryMap.entrySet()) {
System.out.println("Country: "+entry.getKey()+" : Capital: "+entry.getValue());
}
}
public static void iterateMapUsingForEach(Map<String, String> countryMap) {
System.out.println("\n<----------Iterating using forEach method------------>");
countryMap.forEach((k,v)->System.out.println("Country: "+k+" : Capital: "+v));
countryMap.forEach((k,v)->{
// you can implement some business logic here..
});
}
}
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| Output: |
<----------Iterating in normal way------------->
Country: Canada : Capital: Ottawa
Country: USA : Capital: Washington, D.C.
Country: Japan : Capital: Tokyo
Country: India : Capital: Delhi
<----------Iterating using forEach method------------>
Country: Canada : Capital: Ottawa
Country: USA : Capital: Washington, D.C.
Country: Japan : Capital: Tokyo
Country: India : Capital: Delhi
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Java 8 forEach method examples
- Java 8 forEach example with Map
- Java 8 forEach example with List
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String Vs StringBuffer
We know that String is immutable object. We can not change the value
of a String object once it is initiated. If we try to change the value of
the existing String object then it creates new object rather than changing
the value of the existing object. So incase, we are going to do more
modificatios on String, then use StringBuffer. StringBuffer updates the
existing objects value, rather creating new object.
Education is what remains after one has forgotten what one has learned in school.
-- Albert Einstein
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