Java Tips
Tags: java, programming, productivity
Published: 2022-05-29 10:37:04

Below are the tips in Java:

Parsing a string into integer

`int i=Integer.parseInt("200");`

boolean variables
`boolean isJavaFun = true;
boolean isFishTasty = false;`

JSON parsing in java

`import org.json.JSONArray;
import org.json.JSONObject;
public class JSONParsing
{
  public static void main(String[] args) throws Exception
  {
    String jsonInput = "{ 'name': 'thomas','empid':'3',[ {'name': 'Lord','empid':'4'},{'name': 'Sam','empid':'5'}]";
    JSONObject outerObject = new JSONObject(jsonInput);
    JSONObject innerObject = outerObject.getJSONObject("JObjects");
    JSONArray jsonArray = innerObject.getJSONArray("JArray1");
    for (int i = 0, size = jsonArray.length(); i < size; i++)
    {
      JSONObject objectInArray = jsonArray.getJSONObject(i);
      String[] elementNames = JSONObject.getNames(objectInArray);
      System.out.printf("%d ELEMENTS IN CURRENT OBJECT:\n", elementNames.length);
      for (String elementName : elementNames)
      {
        String value = objectInArray.getString(elementName);
        System.out.printf("name=%s, value=%s\n", elementName, value);
      }
      System.out.println();
    }
  }}`

Comparing String

`class StringComparison{  
 public static void main(String args[]){  
   String s1="Sachin";  
   String s2="Sachin";  
   String s3="Ratan";  
   System.out.println(s1.compareTo(s2));//0  
   System.out.println(s1.compareTo(s3));//1(because s1>s3)  
   System.out.println(s3.compareTo(s1));//-1(because s3 < s1 )
}} ` 
   
 Array List Generics, Lambda and ForEach

 ` ArrayList<String> languages = new ArrayList<>();
    languages.add("Java");
    languages.add("Python");
    languages.add("JavaScript");
    System.out.print("ArrayList: ");
    languages.forEach((e) -> {System.out.print(e + ", ") }
	  for (String element : list){
	           if (element.contains("Java")){
	                 System.out.println(element);
	           }
	        }`
			
String splitting, and tokens		
			
  `  String str = "token@thisplace@end";
      String[] arrOfStr = str.split("@", 2);
      for (String a : arrOfStr)
          System.out.println(a)`
		  
		
Handling Spark Data Streams  
		`public static void main(String[] args) {
		      SparkConf conf = new SparkConf().setMaster("local[2]").setAppName("sparkStreamIng");
		      JavaStreamingContext javaStreamingContext = new JavaStreamingContext(conf, Durations.seconds(1));
		      JavaReceiverInputDStream<String> dStream = javaStreamingContext.socketTextStream("localhost", 8080);
		      JavaDStream<String> errorLine = dStream.filter(new Function<String, Boolean>() {
		          @Override
		          public Boolean call(String v1) throws Exception {
		              return v1.contains("error");
		          }
		      });
		      errorLine.print();
		      try {   
		          javaStreamingContext.start();
		      javaStreamingContext.awaitTermination();
		      } catch (InterruptedException e) {
		          e.printStackTrace();
		      }`

Randomizing integer between a range  
			 ` public static int randInt(int min, int max) {
			      Random rand;
			      int randomNum = rand.nextInt((max - min) + 1) + min;
			      return randomNum;
			  }`