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Use the containsKey() method to check whether a particular key exists in IdentityHashMap or not.Create a IdentityHashMapMap m = newIdentityHashMap(); m.put("1", 100); m.put("2", 200); m.put("3", 300); m.put("4", 150); m.put("5", 110); m.put("6", 50); m.put("7", 90); m.put("8", 250); m.put("9", 350); m.put("10", 450);Now, let’s say we need to check whether key 7 exists or not. For that, use the containsKey() method like thism.containsKey(“7”)The following is an example to check for the existence of a key in IdentityHashMapExample Live Demoimport java.util.*; public class Demo { public static void main(String[] args) { Map m = newIdentityHashMap(); m.put("1", 100); ... Read More
While creating a table, in certain scenarios, we need values to column such as ID, to be generated/incremented automatically. Various databases support this feature in different ways.In MySQL database you can declare a column auto increment using the following syntax.CREATE TABLE table_name( ID INT PRIMARY KEY AUTO_INCREMENT, column_name1 data_type1, column_name2 data_type2, column_name3 data_type3, column_name4 data_type4, ............ ........... );While inserting records in a table there is no need to insert value under the auto-incremented column. These will be generated automatically.For example, in a table if we have a column with name ID and data type ... Read More
Overloading is one of the mechanisms to achieve polymorphism. If a class contains two methods with the same name and different parameters, whenever you call this method the method body will be bound with the method call based on the parameters.ExampleIn the following Java program, the Calculator class has two methods with name addition. The only difference between them is that one contains 3 parameters and the other contains 2 parameters.Here, we can call the addition method by passing two integers or three integers. Based on the number of integer values we pass, the respective method will be executed. Live Demopublic ... Read More
In Java a class is a user defined datatype/blue print in which we declare methods and variables.public class Sample{ }Once you declare a class you need to create an object (instantiate) it. You can create an object using various ways −Using new keywordIn general, an object is created using the new keyword as −Sample obj = new Sample();ExampleIn the following Java we have a class with name sample, which has a method (display). From the main method we are instantiating the Sample class and invoking the display() method. Live Demopublic class Sample{ public void display() { System.out.println("This ... Read More
The equals() method compares this string to the specified object. The result is true if and only if the argument is not null and is a String object that represents the same sequence of characters as this object.Example Live Demopublic class Sample{ public static void main(String []args){ String s1 = "tutorialspoint"; String s2 = "tutorialspoint"; String s3 = new String ("Tutorials Point"); System.out.println(s1.equals(s2)); System.out.println(s2.equals(s3)); } }Outputtrue falseYou can also compare two strings using == operator. But, it compares references of the given variables not ... Read More
The higherEntry() method in NavigableMap returns a key-value mapping associated with the least key strictly greater than the given key.The following is an example to implement higherEntry() method −Example Live Demoimport java.util.*; public class Demo { public static void main(String[] args) { NavigableMap n = new TreeMap(); n.put(5, "Tom"); n.put(9, "John"); n.put(14, "Jamie"); n.put(1, "Tim"); n.put(4, "Jackie"); n.put(15, "Kurt"); n.put(19, "Tiger"); n.put(24, "Jacob"); System.out.println("NavigableMap elements..."+n); System.out.println("Higher Entry ... Read More
The lowerEntry() method in NavigabelMap returns a key-value mapping associated with the greatest key strictly less than the given key.The following is an example to implement lowerEntry() methodExample Live Demoimport java.util.*; public class Demo { public static void main(String[] args) { NavigableMap n = new TreeMap(); n.put(5, "Tom"); n.put(9, "John"); n.put(14, "Jamie"); n.put(1, "Tim"); n.put(4, "Jackie"); n.put(15, "Kurt"); n.put(19, "Tiger"); n.put(24, "Jacob"); System.out.println("NavigableMap elements..."+n); System.out.println("Lower Entry is ... Read More
While creating a table, in certain scenarios, we need values to column such as ID, to be generated/incremented automatically. Various databases support this feature in different ways.In MySQL database you can declare a column auto increment using the following syntax.CREATE TABLE table_name( ID INT PRIMARY KEY AUTO_INCREMENT, column_name1 data_type1, column_name2 data_type2, column_name3 data_type3, column_name4 data_type4, ............ ........... );MySQL query to create a table with auto-incremented column.CREATE TABLE Sales( ID INT PRIMARY KEY AUTO_INCREMENT, ProductName VARCHAR (20) NOT NULL, CustomerName VARCHAR (20) NOT NULL, DispatchDate date, DeliveryTime timestamp, Price ... Read More
The floorKey() method is used to get floor key i.e. to return the greatest key less than or equal to the given key, or null if there is no such key.The following is an example to get floor key from NavigableMapExample Live Demoimport java.util.*; public class Demo { public static void main(String[] args) { NavigableMap n = new TreeMap(); n.put("A", 498); n.put("B", 389); n.put("C", 868); n.put("D", 988); n.put("E", 686); n.put("F", 888); n.put("G", 999); ... Read More
Check whether a Map is empty or not using the isEmpty() method.Let us first create a IdentityHashMap and add some elements to itMap m= new IdentityHashMap(); m.put("1", 100); m.put("2", 200); m.put("3", 300); m.put("4", 150); m.put("5", 110); m.put("6", 50); m.put("7", 90); m.put("8", 250); m.put("9", 350); m.put("10", 450);Now, use the following method to check whether the Map is empty or not. Since we added some elements above, therefore the Map is not emptyn.isEmpty();Example Live Demoimport java.util.*; public class Demo { public static void main(String[] args) { Map m = new IdentityHashMap(); m.put("1", 100); m.put("2", 200); m.put("3", 300); m.put("4", 150); ... Read More