Following example helps to determine the rows and columns of a two-dimensional array with the use of arrayname.length.ExampleFollowing example helps to determine the upper bound of a two dimensional array with the use of arrayname.length. public class Main {    public static void main(String args[]) {       String[][] data = new String[2][5];       System.out.println("Dimension 1: " + data.length);       System.out.println("Dimension 2: " + data[0].length);    } }OutputThe above code sample will produce the following result. Dimension 1: 2 Dimension 2: 5

Yes, use String.split() method to do it. See the example below −Examplepublic class Tester {    public static void main(String[] args) {       String text = "This,is,a,comma,seperated,string.";       String[] array = text.split(",");       for(String value:array) {          System.out.print(value + " ");       }    } }OutputThis is a comma seperated string.

You can simply iterate the byte array and print the byte using System.out.println() method.Examplepublic class Tester {    public static void main(String[] args) {       byte[] a = { 1,2,3};       for(int i=0; i< a.length ; i++) {          System.out.print(a[i] +" ");       }    } }Output1 2 3

Yes. Create a list to represent a 2D array and then use Collections.shuffle(list).Exampleimport java.util.ArrayList; import java.util.Collections; import java.util.List; public class Tester {    public static void main(String[] args) {       List rows = new ArrayList();       rows.add(new int[]{1,2,3});       rows.add(new int[]{4,5,6});       rows.add(new int[]{7,8,9});       System.out.println("Before Shuffle");       System.out.println("[0][0] : " + rows.get(0)[0]);       System.out.println("[1][1] : " + rows.get(1)[1]);       System.out.println("After Shuffle");       Collections.shuffle(rows);       System.out.println("[0][0] : " + rows.get(0)[0]);       System.out.println("[1][1] : " + rows.get(1)[1]);    } }OutputBefore Shuffle [0][0] : 1 [1][1] : 5 After Shuffle [0][0] : 7 [1][1] : 2

Following program shows how to initialize an array declared earlier.Examplepublic class Tester {    int a[];    public static void main(String[] args) {       Tester tester = new Tester();       tester.initialize();    }    private void initialize() {       a = new int[3];       a[0] = 0;       a[1] = 1;       a[2] = 2;       for(int i=0; i< a.length ; i++) {          System.out.print(a[i] +" ");       }    } }Output0 1 2

You ByteArrayOutputStream to write byte arrays and get the result using its toByteArray() method.import java.io.ByteArrayOutputStream; import java.io.IOException; public class Tester { public static void main(String[] args) throws IOException { byte[] a = { 1,2,3}; byte[] b = { 4,5,6}; ByteArrayOutputStream baos = new ByteArrayOutputStream(); baos.write(a); baos.write(b); byte[] c = baos.toByteArray(); for(int i=0; i< c.length ; i++){ System.out.print(c[i] +" "); } } }Output1 2 3 4 5 6

If you wish to create a dynamic 2d array in Java without using List. And only create a dynamic 2d array in Java with normal array then click the below linkYou can achieve the same using List. See the below program. You can have any number of rows or columns.Exampleimport java.util.ArrayList; import java.util.List; public class Tester {    public static void main(String[] args) {       List rows = new ArrayList();       rows.add(new int[]{1, 2, 3});       rows.add(new int[]{1, 2});       rows.add(new int[]{1});       //get element at row : 0, column ... Read More

Following example shows how to remove an element from array. Exampleimport java.util.ArrayList; public class Main {    public static void main(String[] args) {       ArrayList objArray = new ArrayList();       objArray.clear();       objArray.add(0,"0th element");       objArray.add(1,"1st element");       objArray.add(2,"2nd element");       System.out.println("Array before removing an element"+objArray);       objArray.remove(1);       objArray.remove("0th element");       System.out.println("Array after removing an element"+objArray);    } }OutputThe above code sample will produce the following result. Array before removing an element[0th element, 1st element, 2nd element] Array after removing an element[2nd element]

You can either setLength to be 0 or create a new StringBuilder() instance. See the example below −Examplepublic class Tester {    public static void main(String[] args) {       StringBuilder builder = new StringBuilder();       builder.append("sample");       System.out.println(builder.toString());       builder.setLength(0);       System.out.println(builder.toString());       builder.append("sample");       System.out.println(builder.toString());    } }Outputsample sample

Performance wise, there is hardly any difference. But it is good to keep a variable local to the scope it is used. So declaring a variable inside Java loop is generally preferred.