Computer java programs

PROGRAM 51
Write a program in Java to display the pattern like right angle triangle
with a number.
SOLUTION:
importjava.util.Scanner;
public class Pattern3{
public static void main(String[] args)
{
inti,j,n;
System.out.print("Input number of rows : ");
Scanner in = new Scanner(System.in);
n =in.nextInt();
for(i=1;i<=n;i++)
{
for(j=1;j<=i;j++)
System.out.print(j);
System.out.println("");
}}}
OUTPUT:
Input number of rows : 10
1
12
123
1234
12345
123456
1234567
12345678
123456789
12345678910

PROGRAM 52
Write a program in Java to make such a pattern like a pyramid with a
number which will repeat the number in the same row.
SOLUTION:
public class Pattern4{
{
inti,j,n,s,x;
System.out.print ("Input number of rows : ");
n =in.nextInt();
s=n+4-1;
for(i=1;i<=n;i++)
{
for(x=s;x!=0;x--)
{
System.out.print(" ");
}
for(j=1;j<=i;j++){
System.out.print(i+" ");
}
System.out.println();
s--;
}}}
OUTPUT:
Input Number of Rows : 4
1
2 2
3 3 3
4 4 4 4

PROGRAM 53
Write a Java program to display Pascal's triangle.
SOLUTION:
public class Pattern5 {
{
intno_row,c=1,blk,i,j;
System.out.print("Input number of rows: ");
no_row=in.nextInt();
for(i=0;i<no_row;i++)
{
for(blk=1;blk<=no_row-i;blk++)
System.out.print(" ");
for(j=0;j<=i;j++)
{
if (j==0||i==0)
c=1;
else
c=c*(i-j+1)/j;
System.out.print(" "+c);
}
System.out.print("n");
}}}
OUTPUT:
Input number of rows: 5
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1

PROGRAM 54
Write a Java program that reads an integer and check whether it is
negative, zero, or positive.
SOLUTION:
public class POSITIVE{
{
System.out.print("Input a number: ");
int n =in.nextInt();
if (n > 0)
{
System.out.println("Number is positive");
}
else if (n < 0)
{
System.out.println("Number is negative");
}
else
{
System.out.println("Number is zero");
}
}
}
OUTPUT:
Input a number: 7
Number is positive

PROGRAM 55
Write a program that accepts three numbers from the user and prints
"increasing" if the numbers are in increasing order, "decreasing" if the
numbers are in decreasing order, and "Neither increasing or decreasing
order" otherwise.
SOLUTION:
public class Number {
{
System.out.print("Input first number: ");
double x =in.nextDouble();
System.out.print("Input second number: ");
double y =in.nextDouble();
System.out.print("Input third number: ");
double z =in.nextDouble();
if (x < y && y < z){
System.out.println("Increasing order");
}
else if (x > y && y > z)
{
System.out.println("Decreasing order");
}
else{
System.out.println("Neither increasing or decreasing order");
}}}
OUTPUT:
Input first number: 1524
Input second number: 2345
Input third number: 3321
Increasing order

PROGRAM 56
Write a Java program to sort a numeric array and a string array.
SOLUTION:
importjava.util.Arrays;
public class Array1 {
public static void main(String[] args){
int[] my_array1 = {1789, 2035, 1899, 1456, 2013,1458, 2458,1254,1472,
2365,1456, 2165, 1457, 2456};
String[]my_array2={"Java","Python","PHP","C#","CProgramming",
"C++"}
System.out.println("Original numeric array
:"+Arrays.toString(my_array1));
Arrays.sort(my_array1);
System.out.println("Sorted numeric array :
"+Arrays.toString(my_array1));
System.out.println("Original string array :
"+Arrays.toString(my_array2));
Arrays.sort(my_array2);
System.out.println("Sorted string array : "+Arrays.toString(my_array2));
}
}
OUTPUT:
Original numeric array : [1789, 2035, 1899, 1456, 2013, 1458, 2458,
1254, 1472, 2365, 1456, 2165, 1457, 2456]
Sorted numeric array : [1254, 1456, 1456, 1457, 1458, 1472, 1789,
1899, 2013, 2035, 2165, 2365, 2456, 2458]
Original string array : [Java, Python, PHP, C#, C Programming, C++]
Sorted string array :[C Programming, C#, C++, Java, PHP, Python]

PROGRAM 57
Write a Java program to calculate the average value of array
elements.
SOLUTION:
publicclassArray2
{
publicstaticvoidmain(String[]args)
{
int[] numbers =newint[]{20,30,25,35,-16,60,-100};
//calculate sum of all array elements
int sum =0;
for(inti=0;i<numbers.length;i++)
{
sum= sum + numbers[i];
//calculate average value
double average = sum /numbers.length;
System.out.println("Average value of the array elements is : "+
average);
}
}
}
OUTPUT:
Average value of the array elements is : 7.0

PROGRAM 58
Write a Java program to insert an element (specific position) into an
array.
SOLUTION:
public static void main(String[] args) {
int[] my_array= {25, 14, 56, 15, 36, 56, 77, 18, 29,
49};
// Insert an element in 3rd position of the array
(index->2, value->5)
intIndex_position= 2;
intnewValue= 5;
System.out.println("Original Array :
"+Arrays.toString(my_array));
for(inti=my_array.length-1; i>Index_position; i--){
my_array[i] =my_array[i-1];
}
my_array[Index_position] =newValue;
System.out.println("New Array:
"+Arrays.toString(my_array));
}
}
OUTPUT:
Original Array : [25, 14, 56, 15, 36, 56, 77, 18, 29, 49]
New Array: [25, 14, 5, 56, 15, 36, 56, 77, 18, 29]

PROGRAM 59
Write a Java program to replace every element with the next
greatest element (from right side) in an given array of integers.
Solution:
import java.io.*;
classArray4 {
public static void main (String[] args)
{
intnums[] = {45, 20, 100, 23, -5, 2, -6};
int result[];
System.out.println("Original Array ");
System.out.println(Arrays.toString(nums));
result = next_greatest_num(nums);
System.out.println("The modified array:");
System.out.println(Arrays.toString(result));
}
staticint [] next_greatest_num(intarr_nums[]) {
int size = arr_nums.length;
intmax_from_right_num = arr_nums[size-1];
arr_nums[size-1] = -1;
for (inti = size-2; i>= 0; i--) {
int temp = arr_nums[i];
arr_nums[i] = max_from_right_num;
if(max_from_right_num< temp)
max_from_right_num = temp;
}
returnarr_nums;
} }
OUTPUT:
Original Array [45, 20, 100, 23, -5, 2, -6]
The modified array:[100, 100, 23, 2, 2, -6, -1]

PROGRAM 60
Write a Java program to separate even and odd numbers of an given
array of integers. Put all even numbers first, and then odd numbers.
Solution:
class Array5{
public static void main (String[] args){
intnums[] = {20, 12, 23, 17, 7, 8, 10, 2, 1, 0};
int result[];
System.out.println(Arrays.toString(nums));
result=separate_odd_even(nums);
System.out.print("Array after separation ");
System.out.println(Arrays.toString(result));}
staticint [] separate_odd_even(intarr[]){
intleft_side= 0, right_side=arr.length- 1;
while (left_side<right_side){
while (arr[left_side]%2 == 0 &&left_side<right_side)
left_side++;
while (arr[right_side]%2 == 1 &&left_side<right_side)
right_side--;
if (left_side<right_side){
int temp =arr[left_side];
arr[left_side] =arr[right_side];
arr[right_side] = temp;
left_side++;
right_side--;}}
returnarr;}}
OUTPUT:
Original Array [45, 20, 100, 23, -5, 2, -6]
The modified array:[100, 100, 23, 2, 2, -6, -1]

PROGRAM 61
Write a Java program to separate 0s on left side and 1s on right side of
an array of 0s and 1s in random order.
Solution:
classArray6 {
intarr[] = new int[]={ 0, 0, 1, 1, 0, 1, 1, 1,0 };
int result[];
System.out.println(Arrays.toString(arr));
int n = arr.length;
result = separate_0_1(arr, n);
System.out.println("New Array ");
System.out.println(Arrays.toString(result));
}
staticint [] separate_0_1(intarr[], int n) {
int count = 0;
for (inti = 0; i< n; i++)
if (arr[i] == 0)
count++;}
for (inti = 0; i< count; i++)
arr[i] = 0;
for (inti = count; i< n; i++)
arr[i] = 1;
returnarr;
}}
OUTPUT:
Original Array [0, 0, 1, 1, 0, 1, 1, 1, 0]
New Array [0, 0, 0, 0, 1, 1, 1, 1, 1]

PROGRAM 62
Write a Java program to find the rotation count in a given rotated
sorted array of integers.
Solution:
importjava.util.*;
importjava.lang.*;
import java.io.*;
public class Array7
{
staticintcount_rotations(intarr_int[], int n)
{
intmin_val=arr_int[0], min_index=-1;
for (inti= 0; i< n; i++)
{
if (min_val>arr_int[i])
{
min_val=arr_int[i];
min_index=i;
}
}
returnmin_index;
}
public static void main (String[] args)
{
intarr_int[] = {35, 32, 30, 14, 18, 21, 27};
// intarr_int[] = {35, 32, 14, 18, 21, 27};
// intarr_int[] = {35, 14, 18, 21, 27};
int n =arr_int.length;
System.out.println(count_rotations(arr_int, n));
}}
OUTPUT:
Number of Rotations = 3

PROGRAM 63
Write a Java program to find all pairs of elements in an array whose
sum is equal to a specified number
Solution:
static void pairs_value(intinputArray[], intinputNumber)
{
System.out.println("Pairs of elements and their sum : ");
for (inti= 0; i<inputArray.length; i++)
{
for (int j = i+1; j <inputArray.length; j++)
{
if(inputArray[i]+inputArray[j] ==inputNumber)
{
System.out.println(inputArray[i]+" + "+inputArray[j]+" =
"+inputNumber);
}
}}}
{
pairs_value(new int[] {2, 7, 4, -5, 11, 5, 20}, 15);
pairs_value(new int[] {14, -15, 9, 16, 25, 45, 12, 8}, 30);
}
}
OUTPUT:
Enter the Number = 15
Pairs of elements and their sum :4 + 11 = 15
-5 + 20 = 15

PROGRAM 64
Write a Java program to add two matrices of the same size
Solution:
public class Array9
{
public static void main(String args[])
{
int m, n, c, d;
System.out.println("Input number of rows of matrix");
m =in.nextInt();
System.out.println("Input number of columns of matrix");
n =in.nextInt();
int array1[][] = new int[m][n];
int array2[][] = new int[m][n];
int sum[][] = new int[m][n];
System.out.println("Input elements of first matrix");
for ( c = 0 ; c < m ; c++ )
{
for ( d = 0 ; d < n ; d++ )
{
array1[c][d] =in.nextInt();
System.out.println("Input the elements of second matrix");
}}
for ( c = 0 ; c < m ; c++ )
for ( d = 0 ; d < n ; d++ )
array2[c][d] =in.nextInt();
for ( c = 0 ; c < m ; c++ )
for ( d = 0 ; d < n ; d++ )
sum[c][d] = array1[c][d] + array2[c][d];
System.out.println("Sum of the matrices:-");

for ( c = 0 ; c < m ; c++ ){
for ( d = 0 ; d < n ; d++ )
System.out.print(sum[c][d]+"t");
System.out.println();
}
}}
OUTPUT:
Input number of rows of matrix
2
Input number of columns of matrix
2
Input elements of first matrix
1 2
34
Input the elements of second matrix
5 6
7 8
Sum of the matrices:-
6 8
10 12

PROGRAM 65
Write a Java program to check if an array of integers without 0 and -1.
Solution:
importjava.util.*;
import java.io.*;
public class Array10
{
{
int[] array_nums= {50, 77, 12, 54, -11};
System.out.println("Original Array: "+Arrays.toString(array_nums));
System.out.println("Result: "+test(array_nums));
}
public static boolean test(int[] numbers)
{
for (int number : numbers)
{
if (number == 0 || number ==-1)
{
return false;
}
}
return true;
}
}
OUTPUT:
Original Array: [50, 77, 12, 54, -11]
Result: true

PROGRAM 66
Write a Java program to check if the sum of all the 10's in the array is
exactly 30. Return false if the condition does not satisfy, otherwise true.
Solution:
importjava.util.*;
import java.io.*;
{
int[] array_nums= {10, 77, 10, 54, -11, 10};
intsearch_num= 10;
intfixed_sum= 30;
System.out.println("Result: "+result(array_nums, search_num,
fixed_sum));
}
public static boolean result(int[] numbers, intsearch_num,
intfixed_sum) {
inttemp_sum= 0;
for (int number : numbers) {
if (number ==search_num) {
temp_sum+=search_num;
}
if (temp_sum>fixed_sum) {
break;
}
}
returntemp_sum==fixed_sum;
}}
OUTPUT:
Original Array: [10, 77, 10, 54, -11, 10]
Result: true

PROGRAM 67
Write a Java program to check if an array of integers contains two
specified elements 65 and 77.
Solution:
importjava.util.*;
import java.io.*;
{
int[] array_nums= {77, 77, 65, 65, 65, 77};
int num1 = 77;
int num2 = 65;
System.out.println("Result: "+result(array_nums, num1, num2));
}
public static boolean result(int[] array_nums, int num1, int num2) {
for (int number :array_nums) {
boolean r = number != num1 && number != num2;
if (r) {
return false;
}
}
return true;
}
}
OUTPUT:
Original Array: [77, 77, 65, 65, 65, 77]
Result: true

PROGRAM 68
Write a Java program to get the character at the given index within the
String.
SOLUTION:
public class String1
{
{
String str= "Java Exercises!";
System.out.println("Original String = " +str);
// Get the character at positions 0 and 10.
int index1 =str.charAt(0);
int index2 =str.charAt(10);
// Print out the results.
System.out.println("The character at position 0 is " +
(char)index1);
System.out.println("The character at position 10 is " +
(char)index2);
}
}
OUTPUT:
Original String = Java Exercises!
The character at position 0 is J
The character at position 10 is i

PROGRAM 69
Write a Java program to trim any leading or trailing
whitespace from a given
string.
Solution:
publicclassString2{
publicstaticvoidmain(String[]args)
{
String str=" Java Exercises ";
// Trim the whitespace from the front and back of the
// String.
String new_str=str.trim();
// Display the strings for comparison.
System.out.println("Original String: "+str);
System.out.println("New String: "+new_str);
}
}
OUTPUT:
Original String: Java Exercises
New String: Java Exercises

PROGRAM 70
Write a program in java To find minimum value using overloading.
Solution:
public class ExampleOverloading{
int a = 11;
int b = 6;
double c = 7.3;
double d = 9.4;
int result1 = minFunction(a, b);
double result2 = minFunction(c, d);
System.out.println("Minimum Value = " + result1);
System.out.println("Minimum Value = " + result2);}
public static intminFunction(int n1, int n2)
{
intmin;if (n1 > n2)min = n2;
elsem in = n1;
return min;
}
public static double minFunction(double n1, double n2)
{
double min;
if (n1 > n2)
min = n2;
elsemin = n1;
return min;
}
}
OUTPUT:
Minimum Value = 6
Minimum Value = 7.3

PROGRAM 71
Write a program in Java to show the use of this keyword.
Solution:
public class This_Example
{
intnum = 10;
This_Example() {
System.out.println("This is an example program on keyword this");
}
This_Example(intnum) {
this();
this.num = num;
}
public void greet() {
System.out.println("Hi Welcome to Tutorialspoint");
}
public void print() {
intnum = 20;
System.out.println("value of local variable num is : "+num);
System.out.println("value of instance variable num is : "+this.num);
this.greet();
}
{
This_Example obj1 = new This_Example(); obj1.print();
This_Exampleobj2 = new This_Example(30); obj2.print();
}}
OUTPUT:
This is an example program on keyword this value of local variable
numis : 20
value of instance variable num is : 10

PROGRAM 72
Write a program in java to demonstrate InputStream and
OutputStream.
SOLUTION:
import java.io.*;
public class fileStreamTest {
public static void main(String args[]) {
try {
bytebWrite [] = {11,21,3,40,5};
OutputStreamos = new FileOutputStream("test.txt"); for(int x = 0; x
<bWrite.length ; x++)
{
os.write(bWrite[x] );
}
os.close();
InputStream is = new FileInputStream("test.txt");
int size = is.available();
for(inti = 0; i< size; i++) {
System.out.print((char)is.read() + " ");
}
is.close();
}
catch (IOException e) {
System.out.print("Exception");
}}}
OUTPUT:
The above code would create file test.txt and would write given
numbers in binary format. Same would be the output on the
stdout screen.

PROGRAM 73
Write a program in java to create
"/tmp/user/java/bin" directory.
SOLUTION:
importjava.io.File;
public class CreateDir
{
{
String dirname ="/tmp/user/java/bin";
File d = new File(dirname); // Create directory
now. d.mkdirs();
}
}
OUTPUT:
Compile and execute the above code to create
"/tmp/user/java/bin".

PROGRAM 74
Write a program in java to list down all the files and directories
available in a directory.
SOLUTION:
importjava.io.File;
public class ReadDir
{
{
File file = null;
String[] paths;
try
{
// create new file object
file = new File("/tmp");
// array of files and directory
paths = file.list();
// for each name in the path array
for(String path:paths)
{
// prints filename and directory name
System.out.println(path);
}}
catch (Exception e) {
// if any error occurs
e.printStackTrace();
} }}
OUTPUT:
test1.txt
test2.txt
ReadDir.java
ReadDir.class

PROGRAM 75
Write a program in java to throw Exceptions occurred by Index
of an array
public class ExcepTest
{
{
int a[] = new int[2];
try
{
System.out.println("Access element three :" + a[3]);
}
catch (ArrayIndexOutOfBoundsException e) {
System.out.println("Exception thrown :" + e); }
finally
{
a[0] = 6;
System.out.println("First element value: " + a[0]);
System.out.println("The finally statement is executed");
}
}
}
OUTPUT:
Exception
thrown:java.lang.ArrayIndexOutOfBoundsException: 3
First element value: 6
The finally statement is executed

PROGRAM 76
Write a program in Java to print the multiplication of two matrices.
public class MatrixMultiplicationExample
{
{
int a[][]={{1,1,1},{2,2,2},{3,3,3}};
int b[][]={{1,1,1},{2,2,2},{3,3,3}};
//creating another matrix to store the multiplication of two matrices
int c[][]=new int[3][3];
for(int i=0;i<3;i++)
{
for(int j=0;j<3;j++)
{
c[i][j]=0;
for(int k=0;k<3;k++)
{
c[i][j]+=a[i][k]*b[k][j];
}
System.out.print(c[i][j]+" ");
}
System.out.println();//new line
}}}
OUTPUT:
First matrix: Second matrix:
1 1 1 1 1 1
2 2 2 2 2 2
3 3 3 3 3 3
Multiplied Matrix:
6 6 6
12 12 12
18 18 18

PROGRAM 77
Write a Java program to find the longest word in a text file
SOLUTION:
import java.io.*;
public class Exercise18 {
public static void main(String [ ] args) throws FileNotFoundException {
new Exercise18().findLongestWords();
}
public String findLongestWords() throws FileNotFoundException {
String longest_word= "";
String current;
Scanner sc= new Scanner(new File("/home/students/test.txt"));
while (sc.hasNext()) {
current=sc.next();
if (current.length() >longest_word.length()) {
longest_word= current;
}
}
System.out.println("n"+longest_word+"n");
returnlongest_word;
}
}
OUTPUT:
general-purpose,

PROGRAM 78
Write a Java program to write and read a plain text file.
SOLUTION:
import java.io.*;
public class Eexercise15 {
public static void main(String a[]){
StringBuildersb= new StringBuilder();
String strLine= "";
try
{
String filename= "/home/students/myfile.txt";
FileWriterfw= new FileWriter(filename,false);
fw.write("Python Exercisesn");
fw.close();
BufferedReaderbr= new BufferedReader(new
FileReader("/home/students/myfile.txt"));
while (strLine!= null)
{
sb.append(strLine);
sb.append(System.lineSeparator());
strLine=br.readLine();
System.out.println(strLine);
}
br.close();
}
catch(IOExceptionioe)
{
System.err.println("IOException: " +ioe.getMessage());
}}}
OUTPUT:
Python Exercises
Null

PROGRAM 79
Write a Java program to append text to an existing file.
SOLUTION:
importjava.io.FileWriter;
String strLine= "";
try{
String filename= "/home/students/myfile.txt";
FileWriterfw= new FileWriter(filename,true);
fw.write("Java Exercisesn");
fw.close();
FileReader("/home/students/myfile.txt"));
//read the file content
{
sb.append(strLine);
}
br.close();
}
catch(IOExceptionioe){
System.err.println("IOException: " +ioe.getMessage());
}}}
OUTPUT:
Python Exercises
Java Exercises
null

PROGRAM 80
Write a Java program to read first 3 lines from a file.
SOLUTION:
importjava.io.FileInputStream;
BufferedReaderbr= null;
String strLine= "";
try {
LineNumberReader reader = new LineNumberReader(new
InputStreamReader(new FileInputStream("/home/students/test.txt"),
"UTF-8"));
while (((strLine=reader.readLine()) != null) &&reader.getLineNumber()
<= 3){
}
reader.close();
} catch (FileNotFoundException e) {
System.err.println("File not found");
} catch (IOException e) {
System.err.println("Unable to read the file.");
}
}}
OUTPUT:
Welcome to w3resource.com.
Append this text.Append this text.Append this text.
Append this text.

PROGRAM 81
Write a program to show the Dynamic Method Dispatch using
inheritance.
SOLUTION:
class parent1{
void sum(inti, int j){
System.out.println(“Parent class” + (i+j));
}}
class child1 extends parent1{
void sum(inti, int j){
System.out.println(“Child class” + (i+j));}}
classdynamic_test{
public static void main(String args[]){
parent1 p1=new parent1();
child1 c1=new child1();
parent1Refi;
Refi=p1;
Refi.sum(10,20);
Refi=c1;
Refi.sum(20,30);
}}
Output:
Parent class 30 Child class 50

PROGRAM: 82
Write a program to accept 10 different word in array and pass the array
to function. Search the word enter by the user is present or not.
SOLUTION:
import java.io.*;
class Searching{
int search(String name[],String ns){
inti,p=0;
for(j=0;j<10;j++){
if(name[j].equals(ns))
p=1;}
return p;}
public static void main()throws IOException{
inti,k=0;
String name[]=new String[10];String ns;
BufferedReaderbr=new BufferedReader(new InputStreamReader(System.in));
Searching ob=new Searching();
System.out.println(“Enter 10 names”);
for(i=0;i<10;i++){
name[i]=br.readLine();}
System.out.println(“Enter the name to be searched:”);
ns=in.readLine();
k=ob.search(name,ns);
if(k==1)
System.out.println(“Search successful”);
else
System.out.println(“NO such name is present”);
}}
OUTPUT:
Enters 10 names
aman, jyoti, deepa, pawan, mayank, arif, abhishek, vishal, lavi, ravi
Enter the name to be searched: arjun
No such name is present

PROGRAM: 83
Write a program in java to accept two numbers and find their sum
using function by creating the object of class.
SOLUTION:
import java.io.*;
public class Addition{
int sum(inta,int b){
int c;
c=a+b;
return c;
}
public static void main()throws IOException{
intm,n,k;
BufferedReaderbr=new BufferedReader(new
InputStreamReader(System.in));
Addition ob=new Addition();
System.out.println(“Enter two numbers”);
m=Integer.parseInt(br.readLine());
n=Integer.parseInt(br.readLine());
k=ob.sum(m,n);
System.out.println(“The sum of two numbers:” + k);
}
}
OUTPUT:
Enter two numbers
3
4
The sum of two numbers: 7

PROGRAM: 84
Write a program to find all combination of four elements of an given
array whose sum is equal to a given value.
SOLUTION:
importjava.util.*;
importjava.lang.*;
class Main
{
{
intnum[]={10, 20, 30, 40, 1, 2};
int n=num.length;
int s=53;
System.out.println(“The given:” + s);
System.out.println(“The combination of four elements:”);
for(inti=0;i<n-3;i++){
for(int j=i+1;j<n-2;j++){
for(int k=j+1;k<n-1;k++){
for(int l=k+1;l<n;l++)
{
if(num[i]+num[j]+num[k]+num[l]==s)
System.out.print(num[i]+ “ “ + num[j]+ “ “ + num[k]+ “ “+ num[l]);
}}}}
}}
OUTPUT:
Given value: 53
Combination of four elements:
10 40 1 2
20 30 1 2

PROGRAM 85
Write a Java program to store text file content line by line into an
array.
SOLUTION:
String strLine= "";
List<String> list = new ArrayList<String>();
try {
FileReader("/home/students/test.txt"));
{
sb.append(strLine);
if (strLine==null)
break;
list.add(strLine);}
System.out.println(Arrays.toString(list.toArray()));
br.close();
}}}
OUTPUT:
[Append this text.Append this text.Append this text., Append this text.,
Append this text.]

PROGRAM 86
Write a java program to read a file line by line and store it into a
variable.
SOLUTION:
importjava.io.FileReader;
public class exercise13 {
String strLine= "";
String str_data= "";
try {
FileReader("/home/students/test.txt"));
{
if (strLine== null)
break;
str_data+=strLine;
}
System.out.println(str_data);
br.close();
}}}
OUTPUT:
Welcome to w3resource.com.Append this text.Appendthistext.Append
this text.Append this text.Append this text.Append this text.Append
this text.

PROGRAM 87
Write a Java program to print all the LEADERS in the array.
Note: An element is leader if it is greater than all the elements to
its right side.
SOLUTION:
class Main
{
{
intarr[] = {10, 9, 14, 23, 15, 0, 9}; int size = arr.length;
for (inti = 0; i< size; i++)
{
int j;
for (j = i + 1; j < size; j++)
{
if (arr[i] <= arr[j])
break;
}
if (j == size)
System.out.print(arr[i] + " ");
}
}
}
OUTPUT:
23 15 9

PROGRAM 88
Write a Java program to find the sum of the two elements of a given
array which is equal to a given integer.
SOLUTION:
importjava.util.*;
public class Exercise35{
public static ArrayList<Integer>two_sum_array_target(final List<Integer> a,
int b) {
HashMap<Integer, Integer>my_map= new HashMap<Integer, Integer>();
ArrayList<Integer> result = new ArrayList<Integer>();
result.add(0);
result.add(0);
for(inti= 0; i<a.size(); i++){
if(my_map.containsKey(a.get(i))){
int index =my_map.get(a.get(i));
result.set(0, index + 1);
result.set(1, i+ 1);
break;}
else{
my_map.put(b -a.get(i), i);
}}
return result;
}
ArrayList<Integer>my_array= new ArrayList<Integer>();
my_array.add(1);
my_array.add(2);my_array.add(4);my_array.add(5);my_array.add(6);
int target = 6;
ArrayList<Integer> result =two_sum_array_target(my_array, target);
for(inti: result)
System.out.print("Index: "+i+ " ");}}
OUTPUT:
Index 1 Index ⁴

PROGRAM 90
Write a Java program to join two linked lists.
Solution:
importjava.util.*;
// create an empty linked list
LinkedList<String> c1 = new LinkedList<String> ();
c1.add("Red");
c1.add("Green");
c1.add("Black");
c1.add("White");
c1.add("Pink");
System.out.println("List of first linked list: " + c1);
c2.add("Red");
c2.add("Green");
c2.add("Black");
c2.add("Pink");
System.out.println("List of second linked list: " + c2);
LinkedList<String> a = new LinkedList<String> ();
a.addAll(c1);
a.addAll(c2);
System.out.println("New linked list: " + a);
}}
OUTPUT:
List of first linked list: [Red, Green, Black, White, Pink]
List of second linked list: [Red, Green, Black, Pink]
New linked list: [Red, Green, Black, White,Pink,Red,Green,Black, Pink]

PROGRAM 91
Write a Java program to shuffle the elements in a linked list.
SOLUTION:
importjava.util.*;
LinkedList<String>l_list= new LinkedList<String> ();
// use add() method to add values in the linked list
l_list.add("Red");
l_list.add("Green");
l_list.add("Black");
l_list.add("Pink");
l_list.add("orange");
// print the list
System.out.println("Linked list before shuffling:n" +l_list);
Collections.shuffle(l_list);
System.out.println("Linked list after shuffling:n" +l_list);
}
}
OUTPUT:
Linked list before shuffling:[Red, Green, Black, Pink, orange]
Linked list after shuffling: [orange, Pink, Red, Black, Green]

PROGRAM 92
Write a Java program to remove and return the first element of
a linked list.
SOLUTION:
importjava.util.*;
public class Exercise19
{
{
c1.add("Red");
c1.add("Green");
c1.add("Black");
c1.add("White");
c1.add("Pink");
System.out.println("Original linked list: " + c1);
System.out.println("Removed element: "+c1.pop());
System.out.println("Linked list after pop operation: "+c1);
}
}
OUTPUT:
Original linked list: [Red, Green, Black, White, Pink]
Removed element: Red Linked list after pop operation: [Green,
Black, White, Pink]

PROGRAM 93
Write a Java program to retrieve but does not remove, the first element
of a linked list.
SOLUTION:
importjava.util.*;
publicclassExercise20{
publicstaticvoidmain(String[]args){
LinkedList<String> c1 =newLinkedList<String>();
c1.add("Red");
c1.add("Green");
c1.add("Black");
c1.add("White");
c1.add("Pink");
System.out.println("Original linked list: "+ c1);
// Retrieve but does not remove, the first element of a linked list
String x =c1.peekFirst();
System.out.println("First element in the list: "+ x);
System.out.println("Original linked list: "+ c1);
}
}
OUTPUT:
First element in the list: Red

PROGRAM 94
Write a Java program to retrieve but does not remove, the last element
of a linked list.
SOLUTION:
importjava.util.*;
c1.add("Red");
c1.add("Green");
c1.add("Black");
c1.add("White");
c1.add("Pink");
// Retrieve but does not remove, the last element of a linked list
String x =c1.peekLast();
System.out.println("Last element in the list: " + x);
}
}
OUTPUT:
Last element in the list: Pink

PROGRAM 95
Write a Java program to retrieve and remove the first element of a tree
set.
SOLUTION:
importjava.util.TreeSet;
importjava.util.Iterator;
// creating TreeSet
TreeSet<Integer>tree_num= new TreeSet<Integer>();
TreeSet<Integer>treeheadset= new TreeSet<Integer>();
// Add numbers in the tree
tree_num.add(10);
tree_num.add(22);
tree_num.add(36);
tree_num.add(25);
tree_num.add(16);
tree_num.add(70);
tree_num.add(82);
tree_num.add(89);
tree_num.add(14);
System.out.println("Original tree set: "+tree_num);
System.out.println("Removes the first(lowest) element:
"+tree_num.pollFirst());
System.out.println("Tree set after removing first element: "+tree_num);
}
}
OUTPUT:
Original tree set: [10, 14, 16, 22, 25, 36, 70, 82, 89]
Removes the first(lowest) element: 10
Tree set after removing first element: [14, 16, 22, 25, 36, 70, 82, 89]

PROGRAM 96
Write a Java program to retrieve and remove the last element of a tree
set.
SOLUTION:
// creating TreeSet
tree_num.add(10);
tree_num.add(22);
tree_num.add(36);
tree_num.add(25);
tree_num.add(16);
tree_num.add(70);
tree_num.add(82);
tree_num.add(89);
tree_num.add(14);
System.out.println("Removes the last element: "+tree_num.pollLast());
System.out.println("Tree set after removing last element: "+tree_num);
}
}
OUTPUT:
Removes the last element: 89
Tree set after removing last element: [10, 14, 16, 22, 25, 36, 70, 82]

PROGRAM 97
Write a Java program to remove a given element from a tree set.
SOLUTION:
// creating TreeSet
tree_num.add(10);
tree_num.add(22);
tree_num.add(36);
tree_num.add(25);
tree_num.add(16);
tree_num.add(70);
tree_num.add(82);
tree_num.add(89);
tree_num.add(14);
System.out.println("Removes 70 from the list:
"+tree_num.remove(70));
System.out.println("Tree set after removing last
element: "+tree_num);
}
}
OUTPUT:
Removes 70 from the list: true
Tree set after removing last element: [10, 14, 16, 22, 25, 36,82, 89]

PROGRAM 98
Write a Java program to change priorityQueue to maximum
priorityqueue.
SOLUTION:
importjava.util.*;
public class Example12 {
PriorityQueue<Integer> pq1 = new PriorityQueue<>(10,
Collections.reverseOrder());
// Add numbers in the Queue
pq1.add(10);
pq1.add(22);
pq1.add(36);
pq1.add(25);
pq1.add(16);
pq1.add(70);
pq1.add(82);
pq1.add(89);
pq1.add(14);
System.out.println("nOriginal Priority Queue: "+pq1);
System.out.print("nMaximum Priority Queue: ");
Integer val= null;
while( (val= pq1.poll()) != null) {
System.out.print(val+" ");
}
System.out.print("n");
}
}
OUTPUT:
Original Priority Queue: [89, 82, 70, 25, 16, 22, 36, 10, 14]
Maximum Priority Queue: 89 82 70 36 25 22 16 14 10

PROGRAM 99
Write a Java program to convert a Priority Queue elements to a string
representation.
SOLUTION:
importjava.util.*;
// Create Priority Queue
PriorityQueue<String> pq1 = new PriorityQueue<String>();
// use add() method to add values in the Priority Queue
pq1.add("Red");
pq1.add("Green");
pq1.add("Black");
pq1.add("White");
System.out.println("Original Priority Queue: "+pq1);
//Convert Priority Queue to a string representation
String str1;
str1 =pq1.toString();
System.out.println("String representation of the Priority Queue:
"+str1);
}
}
OUTPUT:
Original Priority Queue: [Black, Red, Green, White]
String representation of the Priority Queue: [Black, Red,
Green, White]

PROGRAM 100
Write a Java program to convert a priority queue to an array containing
all of the elements of the queue.
SOLUTION:
importjava.util.*;
// Create Priority Queue
PriorityQueue<String> pq1 = new PriorityQueue<String>();
// use add() method to add values in the Priority Queue
pq1.add("Red");
pq1.add("Green");
pq1.add("Black");
pq1.add("White");
System.out.println("Original Priority Queue: "+pq1);
//Convert a linked list to array list
List<String>array_list= new ArrayList<String>(pq1);
System.out.println("Array containing all of the elements in the
queue: "+array_list);
}
}
OUTPUT:
Original Priority Queue: [Black, Red, Green, White]
Array containing all of the elements in the queue: [Black, Red,
Green, White]

Computer java programs

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