InstanceOfJava

How to convert list to set in java with example program

Posted by: Instanceofjava Posted date: 10:49 PM / comment : 0 java Collections interview Questions , java programming interview questions

Java program to convert list to set.
Convert ArrayList of string to HashSet in java example program
How to convert List to Set in java
Set<String> strSet = new HashSet<String>(arrList);
HashSet having a constructor which will take list as an argument.
Lets see how to convert list to Set using java program.

#1: Java Example Program to Convert List to Set.

package com.instanceofjava;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Set;
public class ListToSet {
/**
* @author www.Instanceofjava.com
* @category interview questions
*
* Description: Convert List to set in java with example program
*
*/
public static void main(String[] args) {
ArrayList<String> arrList= new ArrayList<>();
arrList.add("Java");
arrList.add("List to String");
arrList.add("Example Program");
Set<String> strSet = new HashSet<String>(arrList);
System.out.println(strSet);
}
}

Output:

[Java, Example Program, List to String]

Using java.util.stream we can convert List to set in java 8
We can use java 8 java.util.stream.Collectors
arrList.stream().collect(Collectors.toSet());

#2: Java Example program to convert List to Set using java 8.

package com.instanceofjava;
import java.util.ArrayList;
import java.util.Set;
import java.util.stream.Collectors;
public class ListToSet {
/**
* @author www.Instanceofjava.com
* @category interview questions
*
* Description: Convert List to set in java with example program
*
*/
public static void main(String[] args) {
ArrayList<String> arrList= new ArrayList<>();
arrList.add("Java");
arrList.add("List to String");
arrList.add("Example Program");
Set<String> strSet = arrList.stream().collect(Collectors.toSet());
System.out.println(strSet);
}
}

Output:

How to convert list to comma separated string using java 8

Posted by: Instanceofjava Posted date: 12:05 AM / comment : 0 java programming interview questions

Howto convert list to comma separated string using java 8 stream.
By using collect() method of stream and Collectors.join(",") method we can convert list to comma separated string in java 8.
Java Example program to convert list of strings to comma separated string.

#1: Java Example program to convert list to comma separated string using java 8 stream.

package com.instanceofjava;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.stream.Collectors;
/**
* @author www.Instanceofjava.com
* @category interview programming questions
*
* Description: convert ArrayList of strings tp comma separated string using java 8
*
*/
public class ArrayToString {
public static void main(String[] args) {
ArrayList<String> colours =new ArrayList<>();
colours.add("Red");
colours.add("Green");
colours.add("Orange");
String result = colours.stream().collect(Collectors.joining(","));
System.out.println(result);
}
}

Output:

Red,Green,Orange

convert list to comma separated string using java 8

How to remove square brackets from string in java

Posted by: Instanceofjava Posted date: 11:38 PM / comment : 1 java string interview programs

Remove square brackets from string in java.
We can remove square brackets from string by using regular expressions.
By using regular expressions we can remove any special characters from string.
Now , we will check how to remove brackets from a string using regular expressions in java.

#1: Java Example program to remove brackets from string using regex.

package com.instanceofjava;
/**
* @author www.Instanceofjava.com
* @category interview programming questions
*
* Description: remove square brackets from string
*
*/
public class ArrayToString {
public static void main(String[] args) {
String strbrackets = "[String nundi ][brackets][remove cheyyadam][yela?]";
strbrackets = strbrackets.replaceAll("\\[", "").replaceAll("\\]","");
System.out.println(strbrackets);
}
}

Output:

String nundi bracketsremove cheyyadamyela?

#2: Java program to remove curly brackets from string

remove square brackets from string java curly

How to convert array to string without brackets in java

Posted by: Instanceofjava Posted date: 11:11 PM / comment : 0 arrays , java programming interview questions , java string interview programs

Converting array to string and string should not contain any brackets.
We can convert array to string by iterating array and capturing each element from an array and append to StringBuilder/StringBuffer so that final output will be string without brackets.
Lets see an example java program to convert array to string by removing brackets.
So that we can remove brackets from string.

#1 : Java Example program to convert array to string without brackets.

package com.instanceofjava;
/**
* @author www.Instanceofjava.com
* @category interview programming questions
*
* Description: convert array to string without brackets.
*
*/
public class ArrayToString {
public static void main(String[] args) {
String array[]= {"java","string","without","brackets"};
StringBuffer strbuffer = new StringBuffer();
for (String str : array) {
strbuffer.append(str).append(" ");
}
String result = strbuffer.toString();
System.out.println(result);
}
}

Output:

java string without brackets

convert array to string without brackets

Java Program to convert ArrayList to String array

Posted by: Instanceofjava Posted date: 11:09 PM / comment : 0 ArrayList , arrays , java programming interview questions

Java code to convert arraylist to string array.
We can convert ArrayList of strings to String array by using toArray() method.
Lets see an Example java program to convert ArrayList to string array.

#1: Java example program to convert ArrayList to String Array

package com.instanceofjava;
import java.util.ArrayList;
import java.util.List;
public class ArrayListToStringArray {
/**
* @author www.Instanceofjava.com
* @category interview programs
*
* Description: Java Prorgam to convert ArrayList to String array
*
*/
public static void main(String[] args) {
List<String> lstflowers = new ArrayList<String>();
lstflowers.add("Rose");
lstflowers.add("Lilly");
String[] arrayflower = new String[lstflowers.size()];
arrayflower = lstflowers.toArray(arrayflower);
for(String flower : arrayflower)
System.out.println(flower);
}
}

Output:

Rose
Lilly

#2: Java example program to convert ArrayList to String Array Using java 8

package com.instanceofjava;
import java.util.ArrayList;
import java.util.List;
public class ArrayListToStringArray {
/**
* @author www.Instanceofjava.com
* @category interview programs
*
* Description: Java Prorgam to convert ArrayList to String array using java 8
*
*/
public static void main(String[] args) {
List<String> lstflowers = new ArrayList<String>();
lstflowers.add("Rose");
lstflowers.add("Lilly");
String[] arrayflower = lstflowers.toArray(new String[lstflowers.size()]);
for(String flower : arrayflower)
System.out.println(flower);
}
}

java program to convert arraylist to string array

Java 8 subtract N minutes from current date

Posted by: Instanceofjava Posted date: 10:47 PM / comment : 0 Java 8 , java programming interview questions

Java 8 provides java.time.LocalDateTime class.
By using minusMinutes() methods of LocalDateTime class we can subtract minutes from date or current date in java.
Lets see an example program on how to remove / subtract n minutes from current date using java 8.

package com.instanceofjava.java8;
import java.time.LocalDateTime;
/**
* @author www.Instanceofjava.com
* @category interview programs
*
* Description: subtract minutes to current date using java 8
*
*/
public class AddMinutesToDate {
public static void main(String[] args) {
//create data using java 8 LocalDateTime
LocalDateTime datetime= LocalDateTime.now();
System.out.println("Before subtracting 30 minutes to date: "+datetime);
//add seconds by using minuesMinutes(seconds) method
datetime=datetime.minusMinutes(30);
System.out.println("After subtracting 30 minutes to date: "+datetime);
}
}

Output:

Before subtracting 30 minutes to date: 2018-02-05T22:41:42.463
After subtracting 30 minutes to date: 2018-02-05T22:11:42.463

subtract minutes from java 8 date time.png

How to Add N minutes to current date using java 8

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