Java String Examples
1. String Length and Trim Code snippet explains the usage of String class length and trim() method. The…
September 11, 2016 · 8 min read
1. String Length and Trim
Code snippet explains the usage of String class length and trim() method.
- The
length()method returns the length of this string. - The
trim()method returns a copy of the string, with leading and trailing whitespace omitted.
import java.util.Scanner;
public class StringExampleTwo {
public static void main(String args[]) {
Scanner scanner= new Scanner(System.in);
System.out.println("Enter a string with space");
String s1 = scanner.nextLine();
System.out.println("s1 = " + s1);
// Display String Length
System.out.println("The length of s1 is: " + s1.length());
// Removing extra spaces from s1
String s2 = s1.trim();
System.out.println("s2 = " + s2);
System.out.println("The length of s2 is: " + s2.length());
}
}Output
2. String Equality Check
Sample program to test String Equality in Java using equals to () operator and String.equals() method.
public class StringEqualsTest {
public static void main(String[] args) {
String str1 = "hello";
String str2 = str1;
String str3 = new String("hellp");
String str4 = new String("hello 2");
String str5 = "hello";
System.out.println("Comparison using == : " + (str1 == str5));
System.out.println("Comparison using == : " + (str1 == str2));
System.out.println("Comparison Using equals() method : " + str1.equals(str2));
System.out.println("Comparison using == : " + (str3 == str4));
System.out.println("Comparison Using equals() method : " + str3.equals(str4));
}
}Output
3. String Concatenation
Sample Java program to concatenate two strings using plus (+) concatenation operator.
public class StringConcatination {
public static void main(String args[]) {
String str1 = "Hello";
String str2 = "JavaTechig";
// Concatenation
String str3 = str1.concat(str2);
System.out.println("str1 = " + str1);
System.out.println("str2 = " + str2);
System.out.println("str3 = " + str3);
String str4 = "Hello";
// checking equals
if (str4.equals(str1)) {
System.out.println("str4 is equal to str1");
} else {
System.out.println("str4 is not equal to str1");
}
}
}Output
4. Change Uppercase to Lowercase
Quick Java code snippet to change the case of a String in Java. It uses toUpperCase() and toLowerCase() methods present in java.lang.String class to convert the case.
public class StringCase {
public static void main(String args[]) {
String str = "This code snippet is brought you by Java Techhig";
// toUpperCase() method converts the complete string in upper case
String strUpper = str.toUpperCase();
// toLowerCase() method converts the complete string in lower case
String strLower = str.toLowerCase();
// printing changed case string
System.out.println("Upper Case: " + strUpper);
System.out.println("Lower Case: " + strLower);
}
}Output
5. Reverse String
import java.util.Scanner;
class ReverseString
{
public static void main(String args[])
{
String original, reverse = "";
Scanner scanner = new Scanner(System.in);
System.out.println("Enter a string to reverse");
original = scanner.nextLine();
int length = original.length();
for ( int i = length - 1 ; i >= 0 ; i-- ){
reverse = reverse + original.charAt(i);
}
System.out.println("Reverse of entered string is: "+reverse);
}
}Output
6. Reverse String using Recursion
import java.util.Scanner;
public class StringRecursiveReverse {
public String reverseString(String str) {
String reverse = "";
if (str.length() == 1) {
return str;
} else {
reverse += str.charAt(str.length() - 1) + reverseString(str.substring(0, str.length() - 1));
return reverse;
}
}
public static void main(String args[]) {
StringRecursiveReverse srr = new StringRecursiveReverse();
Scanner scanner = new Scanner(System.in);
System.out.println("Enter a string to reverse");
String original = scanner.nextLine();
System.out.println("Result: " + srr.reverseString(original));
}
}Output
7. Compare Strings
import java.util.Scanner;
class CompareStrings {
public static void main(String args[]) {
String str1, str2;
Scanner in = new Scanner(System.in);
System.out.println("Enter the first string");
str1 = in .nextLine();
System.out.println("Enter the second string");
str2 = in .nextLine();
if (str1.compareTo(str2) > 0){
System.out.println("First string is greater than second.");
} else if (str1.compareTo(str2) < 0){
System.out.println("First string is smaller than second.");
} else{
System.out.println("Both strings are equal.");
}
}
}