w3resource

Java Exercises: Check if the value 20 appears three times and no 20's are next to each other in a given array of integers

Java Basic: Exercise-98 with Solution

Write a Java program to check if the value 20 appears three times and no 20’s are next to each other in a given array of integers.

Pictorial Presentation:

Java Basic Exercises: Check if the value 20 appears three times and no 20's are next to each other in a given array of integers

Sample Solution:

Java Code:

import java.util.*; 
import java.io.*; 
 public class Exercise98 {
 public static void main(String[] args)
 {
	int[] array_nums = {10, 20, 10, 20, 40, 13, 20};
		
	int count = 0, result =0;
    
    if(array_nums.length >= 1 && array_nums[0] == 20)
        count++;

    for(int i = 1; i < array_nums.length; i++) {
        if(array_nums[i - 1] == 20 && array_nums[i] == 20)
		{
         System.out.printf( String.valueOf(false));	
         result = 1;
		}                   
        if(array_nums[i] == 20)
            count++;
    }
                                          
    if (result==0)
 	  {
     	 System.out.printf( String.valueOf(count == 3));	         
	  }	
	  System.out.printf("\n");	
    }
}

Sample Output: 

true

Flowchart:

Flowchart: Java exercises: Check if the value 20 appears three times and no 20's are next to each other in a given array of integers

Java Code Editor:

Contribute your code and comments through Disqus.

Previous: Write a Java program to check if an array of integers contains a specified number next to each other or there are two same specified numbers separated by one element.
Next: Write a Java program to check if a specified number appears in every pair of adjacent element of a given array of integers.

What is the difficulty level of this exercise?



Java: Tips of the Day

Execution of console commands:

Java allows you to execute console commands directly from code using a class Runtime. It is very important not to forget about exception handling.

For example, let's try to open a PDF file through a Java terminal:

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
  
public class ShellCommandExec {
  
  public static void main(String[] args) {
    String gnomeOpenCommand = "gnome-open //home//user//Documents//MyDoc.pdf";
  
    try {
      Runtime rt = Runtime.getRuntime();
      Process processObj = rt.exec(gnomeOpenCommand);
  
      InputStream stdin = processObj.getErrorStream();
      InputStreamReader isr = new InputStreamReader(stdin);
      BufferedReader br = new BufferedReader(isr);
  
      String myoutput = "";
  
      while ((myoutput=br.readLine()) != null) {
        myoutput = myoutput+"\n";
      }
      System.out.println(myoutput);
    }
    catch (Exception e) {
      e.printStackTrace();
    }
  }
}