Implementation of Java LinkedHashMap class

Java LinkedHashMap: put() and size() methods

Codeaft.java

import java.util.LinkedHashMap;

class Codeaft 
{
    public static void main(String[] args) 
    {
        //LinkedHashMap class implements the Map interface
        LinkedHashMap<Long,String> lhm = new LinkedHashMap<>();
        lhm.put(25622348989L,"James Moore");
        lhm.put(25622348990L,"Donald Taylor");
        lhm.put(25622348991L,"Edward Parkar");
        lhm.put(25622348992L,"Ryan Bakshi");
        System.out.println(lhm);
        System.out.println("Size: "+lhm.size());
    }
}

Output

codeaft@codeaft:~$ javac Codeaft.java
codeaft@codeaft:~$ java Codeaft
{25622348989=James Moore, 25622348990=Donald Taylor, 25622348991=Edward Parkar, 25622348992=Ryan Bakshi}
Size: 4
codeaft@codeaft:~$

Java LinkedHashMap: keySet() and values() methods

Codeaft.java

import java.util.LinkedHashMap;

class Codeaft 
{
    public static void main(String[] args) 
    {
        //LinkedHashMap class implements the Map interface
        LinkedHashMap<Long,String> lhm = new LinkedHashMap<>();
        lhm.put(25622348989L, "James Moore");
        lhm.put(25622348990L, "Donald Taylor");
        lhm.put(25622348991L, "Edward Parkar");
        lhm.put(25622348992L, "Ryan Bakshi");

        System.out.println(lhm.keySet());
        System.out.println(lhm.values());

        /*
         * for(Long l: lhm.keySet()) { System.out.println(l); }
         * 
         * for(String s: lhm.values()) { System.out.println(s); }
         */
    }
}

Output

codeaft@codeaft:~$ javac Codeaft.java
codeaft@codeaft:~$ java Codeaft
[25622348989, 25622348990, 25622348991, 25622348992]
[James Moore, Donald Taylor, Edward Parkar, Ryan Bakshi]
codeaft@codeaft:~$

Java LinkedHashMap: replace() method

Codeaft.java

import java.util.LinkedHashMap;

class Codeaft 
{
    public static void main(String[] args) 
    {
        //LinkedHashMap class implements the Map interface
        LinkedHashMap<Long,String> lhm = new LinkedHashMap<>();
        lhm.put(25622348989L,"James Moore");
        lhm.put(25622348990L,"Donald Taylor");
        lhm.put(25622348991L,"Edward Parkar");
        lhm.put(25622348992L,"Ryan Bakshi");
        System.out.println(lhm);
        
        lhm.replace(25622348991L, "Edward D Parkar");
        lhm.replace(25622348992L, "Ryan Bakshi", "Ryan S Bakshi");
        System.out.println(lhm);
    }
}

Output

codeaft@codeaft:~$ javac Codeaft.java
codeaft@codeaft:~$ java Codeaft
{25622348989=James Moore, 25622348990=Donald Taylor, 25622348991=Edward Parkar, 25622348992=Ryan Bakshi}
{25622348989=James Moore, 25622348990=Donald Taylor, 25622348991=Edward D Parkar, 25622348992=Ryan S Bakshi}
codeaft@codeaft:~$

Java LinkedHashMap: putAll() and putIfAbsent() methods

Codeaft.java

import java.util.LinkedHashMap;

class Codeaft 
{
    public static void main(String[] args) 
    {
        //LinkedHashMap class implements the Map interface
        LinkedHashMap<Long, String> lhm1 = new LinkedHashMap<>();
        lhm1.put(25622348989L,"James Moore");
        lhm1.put(25622348990L,"Donald Taylor");
        System.out.println(lhm1);
        
        LinkedHashMap<Long, String> lhm2 = new LinkedHashMap<>();
        lhm2.put(25622348991L,"Edward Parkar");
        lhm2.put(25622348992L,"Ryan Bakshi");
        System.out.println(lhm2);
        
        lhm2.putIfAbsent(25622348993L, "Marie Peters");
        lhm1.putAll(lhm2);
        System.out.println(lhm1);
    }
}

Output

codeaft@codeaft:~$ javac Codeaft.java
codeaft@codeaft:~$ java Codeaft
{25622348989=James Moore, 25622348990=Donald Taylor}
{25622348991=Edward Parkar, 25622348992=Ryan Bakshi}
{25622348989=James Moore, 25622348990=Donald Taylor, 25622348991=Edward Parkar, 25622348992=Ryan Bakshi, 25622348993=Marie Peters}
codeaft@codeaft:~$

Java LinkedHashMap: remove() and clear() methods

Codeaft.java

import java.util.LinkedHashMap;

class Codeaft 
{
    public static void main(String[] args) 
    {
        //LinkedHashMap class implements the Map interface
        LinkedHashMap<Long,String> lhm = new LinkedHashMap<>();
        lhm.put(25622348989L,"James Moore");
        lhm.put(25622348990L,"Donald Taylor");
        lhm.put(25622348991L,"Edward Parkar");
        lhm.put(25622348992L,"Ryan Bakshi");
        
        System.out.println(lhm.keySet());
        lhm.remove(25622348991L);
        System.out.println(lhm.keySet());
        
        lhm.clear();
        if(lhm.isEmpty())
        {
            System.out.println("LinkedHashMap is empty now");
        }
    }
}

Output

codeaft@codeaft:~$ javac Codeaft.java
codeaft@codeaft:~$ java Codeaft
[25622348989, 25622348990, 25622348991, 25622348992]
[25622348989, 25622348990, 25622348992]
LinkedHashMap is empty now
codeaft@codeaft:~$

Comments and Reactions

What Next?

Implementation of Java ArrayDeque class Implementation of Java PriorityQueue class Implementation of Java Stack class

Codeaft

Java Programming