Map

• Create map

Map<Integer, String> class2020 = new Map<Integer, String>();

// add a new student/item
class2020.put(11008890, 'Manish');

System.debug(class2020);

class2020.put(11008891, 'Harry');
class2020.put(11008892, 'Rick');
class2020.put(11008893, 'Bill');

System.debug(class2020);

class2020.put(11008894, 'Bill');
System.debug(class2020);

• Update

//update/override value
class2020.put(11008894, 'Skywalker');
System.debug(class2020);

• Get value

// get a value
System.debug(class2020.get(11008892));

• Remove

// remove an item from map
class2020.remove(11008893);
System.debug(class2020);

• List all key

// get all the keys
Set<Integer> rollNumber = class2020.keySet();
System.debug(rollNumber);

• List all value

// get all the values
List<String> students = class2020.values();
System.debug(students);

• Contain key

// check if map has the key
System.debug(class2020.containsKey(11008892));
System.debug(class2020.containsKey(11008893));