Java Program to Multiply 2 matrices

In this program we will take three level nested loop is used to perform the multiplication.First, you have to ask the user to enter the number of rows and columns of the first matrix and then ask to enter the first matrix elements.Again ask the same for the second matrix. Then multiply two matrices and store the multiplication result inside the any variable say res and then print all the matrices as a result


Example:


import java.util.Scanner;
class MatrixExample
{
int m,n,p,q;
int[][] a;
int[][]b;
int[][]c;
public void readData()
{
int i,j;
Scanner sc=new Scanner(System.in);
System.out.println("Enter the order of the matrix A");
m=sc.nextInt();
n=sc.nextInt();
System.out.println("Enter the order of the matrix B");
p=sc.nextInt();
q=sc.nextInt();
if(n!=p)
{
System.out.println("matrix order mismatch for multiplication");
System.exit(0);
}
a=new int[m][n];
b=new int[p][q];
c=new int[m][q];
System.out.println("enter the elements of Matrix A");
for(i=0;i<m;i++)
for(j=0;j<n;j++)
{
System.out.printf("a[%d][%d]=",i,j);
a[i][j]=sc.nextInt();
System.out.println("\n");
}
System.out.println("enter the elements of Matrix B");
for(i=0;i<p;i++)
for(j=0;j<q;j++)
{
System.out.printf("b[%d][%d]=",i,j);
b[i][j]=sc.nextInt();
System.out.println("\n");
}
}
public void multiply()
{
for(int i=0;i<m;i++)
for(int j=0;j<q;j++)
{
c[i][j]=0;
for(int k=0;k<n;k++)
c[i][j]+=a[i][k]*b[k][j];
}
}
public void printMatrix()
{
for(int i=0;i<m;i++)
{
for(int j=0;j<q;j++)
System.out.printf("%d\t",c[i][j]);
System.out.println("\n");
}
}
public static void main(String []args)
{
MatrixExample obj=new MatrixExample();
obj.readData();
obj.multiply();
System.out.println("The result of multiplication is ");
obj.printMatrix();
}
}
Output:

Java Array programs

In this post you will learn some basic and advanced Array programs.These programs will helpful while attend the Technical written Test and Technical Interviews in IT industry.

1. Java Program to read array from keyboard

import java.util.*;
class ArrayList
{
public static void main(String args[])
{
Scanner sc=new Scanner(System.in);
int i;
int a[]=new int[5];
for(i=0;i<5;i++)
{
System.out.println("enter value:");
a[i]=sc.nextInt();
}
System.out.println("\n array elements are:");
for(i=0;i<5;i++)
{
System.out.println(" "+a[i]);
}
}
}
Output:
enter value: 10
enter value:20
enter value:30
enter value:40
enter value:50
array elements are:
10 20 30 40 50

2. Java Program sum elements of array

class SumeOfArray
{
public static void main(String args[])
{
int a[]=new int[5];
int i,sum=0;
a[0]=2;
a[1]=3;
a[2]=4;
a[3]=4;
a[4]=3;
for(i=0;i<a.length;i++)
{
sum=sum+a[i];
}
System.out.println("sum is:"+sum);
}
}
Output:
Sum is: 18

3.Java Program to sort elements of Array

import java.util.Arrays;
import java.util.Comparator;
class ArraysSortDemo
{
public static void main(String args[])
{
int [] a={10,5,20,11,6};
System.out.println("primitive array before sorting:");
for(int a1:a)
{
System.out.println(a1);
}
Arrays.sort(a);
System.out.prinltn("primitive array after sorting");
for(int a1:a)
{
System.out.println(a1);
}
String[] s={"A","Z","B"};
System.out.println("object array before sorting");
for(String a2:s)
{
System.out.println(a2);
}
Arrays.sort(s);
System.out.println("object array after sorting");
for(String a1:s)
{
System.out.println(a1);
}
Arrays.sort(s,new MyComparator());
System.out.println("object array after sorting by comparator:");
for(String a1:s)
{
System.out.println(a1);
}
}
}
class MyComparator implements Comparator
{
public int compare(Object o1,Object o2)
{
String s1=o1.toString();
String s2=o2.toString();
return s2.compareTo(s1);
}
}
Output: 
10
5
20
11
6
Primitive array after sorting
5
6
10
11
20
Object array before sorting
A
Z
B
Object array after sorting
A
B
Z
Object array after sorting by comparator
Z
B
A

4.Java Program To Search Elements of List

import java.util.*;
class CollectionSearchDemo
{
public static void main(String [] args)
{
ArraysList al=new ArrayList();
al.add("apple");
al.add("mango");
al.add("banana");
al.add("grape");
System.out.println(al);
//Collections.sort(al);
System.out.println(al);
System.out.println(Collections.birnarySearch(al,"apple"));
System.out.println(Collections.birnarySearch(al,"mango"));
}
}
Output:
javac CollectionSearchDemo.java
java CollectionSearchDemo
[apple,mango,banana,grape]
[apple,mango,banana,grape]
0
1

5.Java Program to Reverse Elements of List

import java.util.*;
class CollectionReverseDemo
{
public static void main(String args[])
{
ArrayList al=new ArrayList();
al.add(15);
al.add(0);
al.add(45);
al.add(10);
System.out.println(al);
Collections.reverse(al);
System.out.println(al);
}
}

Output
javac CollectionReverseDemo.java
java CollectionReverseDemo
[11,5,6,7]
[7,6,5,11]

6.Java Program to find minimum element from array
class MinimumOfArray
{
public static void main(String args[])
{
int i,min;
int a[]={30,34,2,6,45};
min=a[0];
for(i=0;i<5;i++)
{
if(min>a[i])
{
min=a[i];
}
}
System.out.println("Minimum:"+min)
}
}
Output:
Minimum: 2

7.Java Program to find maximum element from array
class MinimumOfArray
{
public static void main(String args[])
{
int i,max=0;
int a[]={30,34,2,6,45};
min=a[0];
for(i=0;i<5;i++)
{
if(a[i]>max)
{
max=a[i];
}
}
System.out.println("Maximum:"+max)
}
}
Output:
Maximum:45

8. Java Program to explain jagged array

class JaggedArray
{
public static void main(String args[])
int a[]][]=new int[4][];
a[0]=new int[1];
a[1]=new int[2];
a[2]=new int[3];
a[3]=new int[4];
int i,j,x=1;
for(i=0;i<a.length;i++)
{
for(j=0;j<a[i].length;j++)
a[i][j]=x;
x++;
}
}
for(i=0;i<a.length;i++)
{
for(j=0;J<a[i].length;j++)
{
System.out.println(a[i][j])+" ");
}
System.out.println();
}
}
}
Output:
1
2 3
4 5 6
7 8 9 10
for(i=0;i<a.length;