String Operations In JAVA

There are different string operations are available in java.We can change the strings by

• Using string concatenation
• Using inbuilt string methods

String Concatenation:

+ is known as the concatenation operator

String Methods:

• s1.length()
• s1.concat(s2)
• s1.equals(s2) return true or false
• s1.equalsignoreCase(s2) -ignore the case sensitivity(Upper case and lower case)
• s1.contains("a") return true or false
• s1.substring(starting index, ending index)
                      0 1 2 3 4 5 6 ----->starting index
                      W E L C O M E
                      1 2 3 4 5 6 7------->Ending index
                      s.substing(2,5)------>LCO
• s1.replace('e','a')
• s1.replace("com","rom")

 Code:

package LearnJava;

public class StringConcatenation {
   
    public static void main(String args[])
    {
       
        //+     ->Concatenation operator
        //println     ->is used to print on the console with a new line
        //print         ->is just used to print on the console
       
        int a=100;
        int b=200;
       
        String x="Hello";
        String y="World";
       
        double i=10.33;
        double j=11.33;
               
       
        System.out.println(a+b); //300
        System.out.println(x+y); //HelloWorld
       
        System.out.println(a+b+x+y); //300HelloWorld
        System.out.println(x+y+a+b); //HelloWorld100200
        System.out.println(x+y+(a+b)); //HelloWorld300
       
        System.out.println(a+b+x+y+a+x+b+y); //300HelloWorld100Hello200World
        System.out.println(a+b+x+y+a+b);   //300HelloWorld100200
       
        System.out.println(i+j); //21.66
        System.out.println(x+y+i+j); //HelloWorld10.3311.33
       
        System.out.println("HelloWorld"); //HelloWorld
        System.out.println(a); //100
       
        System.out.println("the value of a is:"+a); //the value of a is:100
        System.out.println("the value of b is:"+b); //the value of b is:200
        System.out.println("the sum of a and b is:"+a+b); //the sum of a and b is:100200
        System.out.println("the sum of a and b is"+(a+b)); //the sum of a and b is300
       
        System.out.print("this is a print");
        System.out.println("this is a print line new");//this is a printthis is a print line new
       
       
        /*
              •    s1.length()
            •    s1.concat(s2)
            •    s1.equals(s2) return true or false
            •    s1.equalsignoreCase(s2) -ignore the case sensitivity(Upper case and lower case)
            •    s1.contains("a") return true or false
            •    s1.substring(starting index, ending index)
                    0 1 2 3 4 5 6 ----->starting index
                    W E L C O M E
                    1 2 3 4 5 6 7------->Ending index
                    s.substing(2,5)------>LCO
            •    s1.replace('e','a')
                   s1.replace("com","rom")
       */

       
        String s1="Hello";
        String s2="World";
        String s3="HELLO";
       
        System.out.println(s1.length()); //5
        System.out.println(s1.concat(s2)); //HelloWorld
       
        System.out.println(s1.equals(s3)); //false
        System.out.println(s1.equalsIgnoreCase(s3)); //true
       
        System.out.println(s1.contains("e")); //true
        System.out.println(s1.substring(1, 4)); //ell
        System.out.println(s1.replace('l','R')); //HeRRo
        System.out.println(s1.replace("ell", "ELL")); //HELLo
       
       

    }
   
}

Wrapper Class in JAVA 

Data conversion-String to Integer:

        String x="100";
        System.out.println(x+20); //10020

        int i=Integer.parseInt(x);
        System.out.println(i+20); //120
       
String to double:
        String a="12.33";
        double d=Double.parseDouble(a);
        System.out.println(d); //12.33
       
String to boolean:
        String b="true";
        boolean t=Boolean.parseBoolean(b);
        System.out.println(t); //true
       
Integer to String:
        int y=10;
        String s=String.valueOf(y);
        System.out.println(s+20); //1020
       
Converting an invalid string:
        String z="100A";
        int l=Integer.parseInt(z);
        System.out.println(l); // throw NumberFormatException (In string A is present)