Guava Collections - Table Interface

Table Interface

Table represents a special map where two keys can be specified in combined fashion to refer to a single value. It is similar to creating a map of maps.

package org.fool.guava.collections;

import java.util.Map;
import java.util.Set;

import com.google.common.collect.HashBasedTable;
import com.google.common.collect.Table;

public class TableTest {
	public static void main(String[] args) {
		// Table<R,C,V> == Map<R,Map<C,V>>
		// create a table
		Table<String, String, String> employeeTable = HashBasedTable.create();

		// initialize the table with employee details
		employeeTable.put("IBM", "101", "Mahesh");
		employeeTable.put("IBM", "102", "Ramesh");
		employeeTable.put("IBM", "103", "Suresh");

		employeeTable.put("Microsoft", "111", "Sohan");
		employeeTable.put("Microsoft", "112", "Mohan");
		employeeTable.put("Microsoft", "113", "Rohan");

		employeeTable.put("TCS", "121", "Ram");
		employeeTable.put("TCS", "122", "Shyam");
		employeeTable.put("TCS", "123", "Sunil");

		// get Map corresponding to IBM
		Map<String, String> ibmEmployees = employeeTable.row("IBM");

		System.out.println("List of IBM Employees");
		ibmEmployees.forEach((id, name) -> System.out.println("Emp Id: " + id + ", Name: " + name));

		// get all the unique keys of the table
		Set<String> employers = employeeTable.rowKeySet();
		System.out.print("Employers: ");
		employers.forEach(employer -> System.out.print(employer + " "));
		System.out.println();
		
		//get a Map corresponding to 102
		Map<String,String> employerMap = employeeTable.column("102");
		employerMap.forEach((id, name) -> System.out.println("Emp Id: " + id + ", Name: " + name));
	}
}

 output

List of IBM Employees
Emp Id: 103, Name: Suresh
Emp Id: 101, Name: Mahesh
Emp Id: 102, Name: Ramesh
Employers: IBM TCS Microsoft 
Emp Id: IBM, Name: Ramesh