All functions related to String class in java.

 

package Program;
/**
 *
 * @author Dilip
 */
//import java.util.*;
public class StringDemo {
public static void main(String[] args)
    {
        String str1 = "Hello, World!";
        // Get the character at positions 0 and 12.
        int index1 = str1.charAt(0);
        int index2 = str1.charAt(12);
        // Print out the results.
        System.out.println("charAt");
        System.out.println("The character at position 0 is " +
            (char)index1);
        System.out.println("The character at position 12 is " +
            (char)index2);
        // concat
        // ==========================================================
        String str2 = "This is the beginning ";
        String str3 = "of the new String.";
        // Concatenate the two strings together.
        String str4 = str2.concat(str3);
        // Display the new String.
        System.out.println("\nconcat");
        System.out.println("The concatenated string: " + str4);
        // copyValueOf
        // ==========================================================
        // Populate a character array with data.
        char[] arr1 = new char[] {
            '1', '2', '3', '4'
        };
        // Create a String containig the contents of arr
        // starting at index 1 for length 2.
        String str5 = String.copyValueOf(arr1, 1, 2);
        // Display the results of the new String.
        System.out.println("\ncopyValueOf");
        System.out.println("The new String contains \"" + str5 +
            "\"");
        // endsWith
        // ==========================================================
        String str6 = "My name is Fred";
        String str7 = "My name is Xiao Mei";
        // The String to check the above two Strings to see
        // if they end with this value (ei).
        String endStr = "ei";
        // Do either of the first two Strings end with endStr?
        boolean ends1 = str6.endsWith(endStr);
        boolean ends2 = str7.endsWith(endStr);
        // Display the results of the endsWith calls.
        System.out.println("\nendsWith");
        System.out.println("\"" + str6 + "\" ends with " +
            "\"" + endStr + "\"? " + ends1);
        System.out.println("\"" + str7 + "\" ends with " +
            "\"" + endStr + "\"? " + ends2);
        // replace
        // ==========================================================
        String str10 = "The quick brown fox jumps over the lazy dog.";
        // Replace all the 'd' characters with 'l' characters.
        String str11 = str10.replace('d', 'l');
        // Display the strings for comparison.
        System.out.println("\nreplace");
        System.out.println("old = " + str10);
        System.out.println("new = " + str11);
        // substring
        // ==========================================================
        String str12 = "Navy blue is my favorite color.";
        // Get a substring of the above string starting from
        // index 5.
        String str13 = str12.substring(0,9);
        // Display the two strings for comparison.
        System.out.println("\nsubstring");
        System.out.println("old = " + str12);
        System.out.println("new = " + str13);
        // toLowerCase
        // ==========================================================
        String str14 = "ThIs Is HaRd To ReAd.";
        // Convert the above string to all lowercase.
        String lowerStr = str14.toLowerCase();
        // Display the two strings for comparison.
        System.out.println("\ntoLowerCase");
        System.out.println("old = " + str14);
        System.out.println("lowercase = " + lowerStr);
        // toUpperCase
        // ==========================================================
        String str15 = "ThIs Is HaRd To ReAd.";
        // Convert the above string to all uppercase
        // using the default system Locale.
        //Locale loc = Locale.getDefault();
        String upperStr = str15.toUpperCase();
        // Display the two strings for comparison.
        System.out.println("\ntoUpperCase");
        System.out.println("old = " + str15);
        System.out.println("uppercase = " + upperStr);
        // valueOf
        // ==========================================================
        String hundredStr = String.valueOf(100);
        String minStr = String.valueOf(Integer.MIN_VALUE);
        // Display the string representations of the above
        // int values.
        System.out.println("\nvalueOf");
        System.out.println(hundredStr);
        System.out.println(minStr);
    }
}
Output:
charAt
The character at position 0 is H
The character at position 12 is !
concat
The concatenated string: This is the beginning of the new String.
copyValueOf
The new String contains "23"
endsWith
"My name is Fred" ends with "ei"? false
"My name is Xiao Mei" ends with "ei"? true
replace
old = The quick brown fox jumps over the lazy dog.
new = The quick brown fox jumps over the lazy log.
substring
old = Navy blue is my favorite color.
new = Navy blue
toLowerCase
old = ThIs Is HaRd To ReAd.
lowercase = this is hard to read.
toUpperCase
old = ThIs Is HaRd To ReAd.
uppercase = THIS IS HARD TO READ.
valueOf
100
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