String class in Java

// Java Program to Create a String
import java.io.*;

class GFG {
    public static void main (String[] args) {
      
          // String literal
        String s="Geeks for Geeks String in Java";
 
          System.out.println(s);
    }
}

// Java Program to Create a String
import java.io.*;

class GFG {
    public static void main (String[] args) {
      
          // String literal
        String s1="String1";
          System.out.println(s1);
      
          // Using new Keyword 
          String s2= new String("String2");
          System.out.println(s2);
    }
}

// Java Program to implement String Constructor
import java.nio.charset.Charset;

class Main {
    // Variables in Methods
    static byte[] b_arr = {71, 101, 101, 107, 115};
    static Charset cs = Charset.defaultCharset();
    static char[] char_arr = {'G', 'e', 'e', 'k', 's'};
    static int[] uni_code = {71, 101, 101, 107, 115};
    static StringBuffer s_buffer = new StringBuffer("Geeks");
    static StringBuilder s_builder = new StringBuilder("Geeks");

    public static void main(String[] args) {
        // Method 1
        String s1 = new String(b_arr);
        System.out.println("Method 1: " + s1);
        System.out.println();

        // Method 2
        String s2 = new String(b_arr, cs);
        System.out.println("Method 2: " + s2);
        System.out.println();

        // This is alternative way for Method 2
        String s3 = new String(b_arr, Charset.forName("US-ASCII"));
        System.out.println("Method 2 Alternative: " + s3);
        System.out.println();

        // Method 3
        String s4 = new String(b_arr, 1, 3);
        System.out.println("Method 3: " + s4);
        System.out.println();

        // Method 4
        String s5 = new String(b_arr, 1, 3, cs);
        System.out.println("Method 4: " + s5);
        System.out.println();

        // This is alternative way for Method 4
        String s6 = new String(b_arr, 1, 4, Charset.forName("US-ASCII"));
        System.out.println("Method 4 Alternative: " + s6);
        System.out.println();

        // Method 5
        String s7 = new String(char_arr);
        System.out.println("Method 5: " + s7);
        System.out.println();

        // Method 6
        String s8 = new String(char_arr, 1, 3);
        System.out.println("Method 6: " + s8);
        System.out.println();

        // Method 7
        String s9 = new String(uni_code, 1, 3);
        System.out.println("Method 7: " + s9);
        System.out.println();

        // Method 8
        String s10 = new String(s_buffer);
        System.out.println("Method 8: " + s10);
        System.out.println();

        // Method 9
        String s11 = s_builder.toString();
        System.out.println("Method 9: " + s11);
        System.out.println();
    }
}

// Java code to illustrate different constructors and methods in String class
import java.io.*;
import java.util.*;

class Test
{
    public static void main (String[] args)
    {
        String s= "GeeksforGeeks";
        // or String s= new String ("GeeksforGeeks");

        // Returns the number of characters in the String.
        System.out.println("String length = " + s.length());

        // Returns the character at ith index.
        System.out.println("Character at 3rd position = "
                           + s.charAt(3));

        // Return the substring from the ith  index character
        // to end of string
        System.out.println("Substring " + s.substring(3));

        // Returns the substring from i to j-1 index.
        System.out.println("Substring  = " + s.substring(2,5));

        // Concatenates string2 to the end of string1.
        String s1 = "Geeks";
        String s2 = "forGeeks";
        System.out.println("Concatenated string  = " +
                            s1.concat(s2));

        // Returns the index within the string
        // of the first occurrence of the specified string.
        String s4 = "Learn Share Learn";
        System.out.println("Index of Share " +
                           s4.indexOf("Share"));

        // Returns the index within the string of the
        // first occurrence of the specified string,
        // starting at the specified index.
        System.out.println("Index of a  = " +
                           s4.indexOf('a',3));

        // Checking equality of Strings
        Boolean out = "Geeks".equals("geeks");
        System.out.println("Checking Equality  " + out);
        out = "Geeks".equals("Geeks");
        System.out.println("Checking Equality  " + out);

        out = "Geeks".equalsIgnoreCase("gEeks ");
        System.out.println("Checking Equality " + out);

        //If ASCII difference is zero then the two strings are similar
        int out1 = s1.compareTo(s2);
        System.out.println("the difference between ASCII value is="+out1);
        // Converting cases
        String w1 = "GeeKyMe";
        System.out.println("Changing to lower Case " +
                            w1.toLowerCase());

        // Converting cases
        String w2 = "GeekyME";
        System.out.println("Changing to UPPER Case " +
                            w2.toUpperCase());

        // Trimming the word
        String w4 = " Learn Share Learn ";
        System.out.println("Trim the word " + w4.trim());

        // Replacing characters
        String str1 = "feeksforfeeks";
        System.out.println("Original String " + str1);
        String str2 = "feeksforfeeks".replace('f' ,'g') ;
        System.out.println("Replaced f with g -> " + str2);
    }
}