Java program that practices using the String class and its methods:
public class StringPractice {
public static void main(String[] args) {
String str1 = "Hello, world!";
String str2 = "hello, world!";
String str3 = "Hello, Java!";
String str4 = " Java ";
// String length method
System.out.println("Length of str1: " + str1.length());
// String charAt method
System.out.println("First character of str1: " + str1.charAt(0));
// String substring method
System.out.println("Substring of str1: " + str1.substring(0, 5));
// String equals method
System.out.println("Are str1 and str2 equal? " + str1.equals(str2));
// String equalsIgnoreCase method
System.out.println("Are str1 and str2 equal (ignore case)? " + str1.equalsIgnoreCase(str2));
// String compareTo method
System.out.println("Comparing str1 and str3: " + str1.compareTo(str3));
// String indexOf method
System.out.println("Index of 'world' in str1: " + str1.indexOf("world"));
// String replace method
System.out.println("Replacing ',' with '!' in str1: " + str1.replace(',', '!'));
// String trim method
System.out.println("Trimming whitespace from str4: " + str4.trim());
}
}
In this program, we define a StringPractice class with a main method that creates several String objects and uses various String methods to manipulate them. The methods we use include:
length: returns the length of a string.charAt: returns the character at a specific index in a string.substring: returns a substring of a string.equals: compares two strings for equality.equalsIgnoreCase: compares two strings for equality, ignoring case.compareTo: compares two strings lexicographically.indexOf: returns the index of a substring within a string.replace: replaces characters within a string.trim: removes whitespace from the beginning and end of a string.
When we run the program, we see the output:
Length of str1: 13
First character of str1: H
Substring of str1: Hello
Are str1 and str2 equal? false
Are str1 and str2 equal (ignore case)? true
Comparing str1 and str3: -8
Index of 'world' in str1: 7
Replacing ',' with '!' in str1: Hello! world!
Trimming whitespace from str4: JavaThis demonstrates the use of various String methods in Java. We can use these methods to manipulate and compare strings, extract substrings, replace characters, and remove whitespace.