map for each code example

Example 1: java for map

Map<String, String> map = new HashMap<>();

for(Entry<String, String> entry:map.entrySet()) {
  System.out.println("key: "+entry.getKey()+" value: "+entry.getValue());
}

Example 2: java map foreach

// 1. for-each with Entry
Map<Integer, Integer> map = new HashMap<Integer, Integer>();
for (Map.Entry<Integer, Integer> entry : map.entrySet()) {
    System.out.println("Key = " + entry.getKey() + ", Value = " + entry.getValue());
}


// 2. for-each with key or value each (faster)
Map<Integer, Integer> map = new HashMap<Integer, Integer>();
//iterating over keys only
for (Integer key : map.keySet()) {
    System.out.println("Key = " + key);
}
 
//iterating over values only
for (Integer value : map.values()) {
    System.out.println("Value = " + value);
}


// 3. Using Iterator
Map<Integer, Integer> map = new HashMap<Integer, Integer>();
// With Generic
Iterator<Map.Entry<Integer, Integer>> entries = map.entrySet().iterator();
while (entries.hasNext()) {
    Map.Entry<Integer, Integer> entry = entries.next();
    System.out.println("Key = " + entry.getKey() + ", Value = " + entry.getValue());
}

// No Generic
Map map = new HashMap();
Iterator entries = map.entrySet().iterator();
while (entries.hasNext()) {
    Map.Entry entry = (Map.Entry) entries.next();
    Integer key = (Integer)entry.getKey();
    Integer value = (Integer)entry.getValue();
    System.out.println("Key = " + key + ", Value = " + value);
}

Example 3: foreach map java

Map<String, String> map = ...
for (Map.Entry<String, String> entry : map.entrySet()) {
    System.out.println(entry.getKey() + "/" + entry.getValue());
}

Example 4: java foreach map

map.forEach((k, v) -> System.out.printf( " %s : %d \n" , k,v) );

Example 5: javascript map foreach

const myArray = ['Sam', 'Alice', 'Nick', 'Matt'];

// Appends text to each element of the array
const newArray = myArray.map(name => {
	return 'My name is ' + name; 
});
console.log(newArray); // ['My name is Sam', 'My Name is Alice', ...]

// Appends the index of each element with it's value
const anotherArray = myArray.map((value, index) => index + ": " + value);
console.log(anotherArray); // ['0: Sam', '1: Alice', '2: Nick', ...]

// Starting array is unchanged
console.log(myArray); // ['Sam', 'Alice', 'Nick', 'Matt']