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You can convert an array of Strings to a single array using the collect() method.ExampleLive Demoimport java.util.Arrays; import java.util.stream.Collectors; public class CreatngStringFromArray { public static void main(String args[]) { String [] myArray = {"Welcome", "to", "Tutorialspoint"}; String str = Arrays.stream(myArray).collect(Collectors.joining(" ")); System.out.println(str); } }OutputWelcome to Tutorialspoint
You can extract a substring from a String using the substring() method of the String class to this method you need to pass the start and end indexes of the required substring.ExampleLive Demopublic class Substring { public static void main(String args[]) { String str = "Welcome to Tutorialspoint"; String sub = str.substring(10, 25); System.out.println(sub); } }OutputTutorialspoint
To extract last n characters, simply print (length-n)th character to nth character using the charAt() method.ExampleLive Demopublic class ExtractingCharactersFromStrings { public static void main(String args[]) { String str = "Hi welcome to tutorialspoint"; int n = 5; int initial = str.length()-5; for(int i=initial; i
To find the consonants in the given String compare every character in it using the charAt() method with the vowel letters and remaining are consonants.ExampleLive Demopublic class FindingConsonants { public static void main(String args[]) { String str = new String("Hi Welcome to Tutorialspoint"); for(int i=0; i
Declare an integer, initialize it with 0, in for loop increment it for each character.ExampleLive Demopublic class Sample { public static void main(String args[]) { String str = new String("Hi welcome to Tutorialspoint"); int count = 0; for(int i = 0; i
You can concatenate two Strings using the concat() method.ExampleLive Demopublic class ConcatinatedStrings { public static void main(String args[]) { String str1 = new String("Tutorials"); String str2 = new String( "Point"); String res = str1.concat(str2); System.out.println(res); } }OutputTutorialsPoint
The toString() method returns the current object in String format.ExampleLive Demopublic class Test { public static void main(String args[]) { Test obj = new Test(); System.out.println(obj.toString()); System.out.println("Hello"); } }OutputTest@2a139a55 Hello
When you store a String asString str1 = "Hello";directly, then JVM creates a String object with the given value in a separate block of memory known as String constant pool.And whenever we try to create another String asString str2 = "Hello";JVM verifies whether any String object with the same value exists in the String constant pool, if so, instead of creating a new object JVM assigns the reference of the existing object to the new variable.And when we store String asString str = new String("Hello");using the new keyword, a new object with the given value is created irrespective of the ... Read More
The volatile modifier is used to let the JVM understand that a thread accessing the variable should always merge its own personal copy of the variable with the original in the memory.Accessing a volatile variable synchronizes all the cached copy of the variables in the main memory. Volatile can only be applied to instance variables, which are of type object or private. A volatile object reference can be null.Examplepublic class MyRunnable implements Runnable { private volatile boolean active; public void run() { active = true; while (active) { } } public void stop() { active = false; } }
Java provides javax.json.Json package which contains classes to read a JSON array:Exampleimport java.io.FileOutputStream; import javax.json.Json; import javax.json.JsonArray; import javax.json.JsonWriter; public class JSONArrayToFile { public static void main(String args[]) throws Exception { JsonArray value = Json.createArrayBuilder() .add(Json.createObjectBuilder() .add("id", "1001") .add("Technology", "JavaFX")) .add(Json.createObjectBuilder() .add("id", "1002") .add("Technology", "OpenCV")) .build(); System.out.println(value); JsonWriter writer = Json.createWriter(new FileOutputStream("sampleData")); writer.writeArray(value); writer.close(); } }Output["JavaFX","HBase","JOGL","WebGL"] After deleting ::["JavaFX","HBase","JOGL"]