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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"]
You can remove an element from the JSONArray object using the remove() method. This method accepts an integer and removes the element in that particular index.Exampleimport org.json.JSONArray; public class RemoveFromJsonArray { public static void main(String args[]) throws Exception { String [] myArray = {"JavaFX", "HBase", "JOGL", "WebGL"}; JSONArray jsArray = new JSONArray(); for (int i=0; i < myArray.length; i++) { jsArray.put(myArray[i]); } System.out.println(jsArray); jsArray.remove(3); System.out.println("After deleting ::"+jsArray); } }Output["JavaFX","HBase","JOGL","WebGL"] After deleting ::["JavaFX","HBase","JOGL"]
The get method of the JSONArray class returns the element at a particular index. Using this method, you can get the elements of the JSONArray object and populate the array with them.Exampleimport java.util.Arrays; import org.json.JSONArray; public class JsonToArray { public static void main(String args[]) throws Exception { String [] myArray = {"JavaFX", "HBase", "JOGL", "WebGL"}; JSONArray jsArray = new JSONArray(); for (int i = 0; i < myArray.length; i++) { jsArray.put(myArray[i]); } System.out.println(jsArray); String[] array = new String[myArray.length]; ... Read More
Following is the algorithm for heapsort (maxheap).Step 1 − Create a new node at the end of the heap.Step 2 − Assign new value to the node.Step 3 − Compare the value of this child node with its parent.Step 4 − If the value of parent is less than a child, then swap them.Step 5 − Repeat step 3 & 4 until Heap property holds.Exampleimport java.util.Arrays; import java.util.Scanner; public class Heapsort { public static void heapSort(int[] myArray, int length) { int temp; int size = length-1; for (int i ... Read More
To check to find whether a given array contains three consecutive dates:Convert the given array into a list of type LocalDate.Using the methods of the LocalDate class compare ith, i+1th and i+1th, i+2th elements of the list if equal the list contain 3 consecutive elements.ExampleLive Demoimport java.time.LocalDate; import java.time.Month; import java.util.ArrayList; import java.util.Collections; import java.util.Date; import java.util.List; public class ConsicutiveDate { public static void main(String args[]) { String[] dates = {"5/12/2017", "6/12/2017", "7/12/2017"}; List localDateList = new ArrayList(); for (int i = 0; i
A two-dimensional array is nothing but an array of one dimensional arrays. Therefore to map a two dimensional array into one dimensional arrays.Create arrays equal to the length of the 2d array and, using for loop store the contents of the 2d array row by row in the arrays created above.Examplepublic class Mapping_2DTo1D { public static void main(String args[]) { int [][] array2D = {{7, 9, 8, 5}, {4, 5, 1, 8}, {9, 3, 2, 7}, {8, 1, 0, 9}}; int [] myArray1 = new int[array2D[0].length]; int [] myArray2 = ... Read More