- trim() Removes extra spaces only at the beginning and end.
Example:
String s=" Admin123 ";
System.out.println(s.trim()); // output:"Admin123"
2.equalsIgnoreCase()
Compares two strings ignoring uppercase/lowercase.
Example:
"Vijay".equalsIgnoreCase("vijay"); // true
3.equals() vs ==
== checks memory reference(same object or not).
equals() checks actual content/value.
Example:
String s1="java";
String s2=new String("java");
s1==s2 // output:false
s1.equals(s2) // output:true
4.contains
checks if a substring exists inside a string.Returns true or false.
Example :
String email="test@gmail.com";
email.contains("@"); // output:true
5.split() + loop(count word)
split sentences into words and count occurrences.
Example :
String s="java is easy java is powerful";
String[] arr=s.split(" ");
int count=0;
for(String word :arr){
if(word.equals("java"))
count++;
}
System.out.println(count); // output: 2
6.Reverse String(without StringBuilder)
Traverse from end to start.
Example :
String s="java";
String rev="";
for(int i=s.length()-1;i>=0;i--){
rev+=s.charAt(i);
}
System.out.println(rev); // output:avaj
7.palindrome check
check if string equals its reverse.
Example :
public class PalindromeString {
public static void main(String[] args) {
String str = "madam";
String rev = "";
for (int i = str.length() - 1; i >= 0; i--) {
rev = rev + str.charAt(i);
}
if (str.equals(rev))
System.out.println("Palindrome");
else
System.out.println("Not Palindrome");
}
} // output:palindrome
8.Remove duplicates
Remove repeated characters.maintains unique characters only.
Example :
public class Duplicate1 {
public static void main(String[] args) {
String name="aabbccdd";
String copy="";
for(int i=0;i<name.length();i++) {
if(copy.indexOf(name.charAt(i))==-1) {
copy+=name.charAt(i);
}
}
System.out.println(copy);
}
} // output:abcd
9.substring() :
Extract part of a string.
Eaxmple :
String log="Error:File not Found";
System.out.println(log.substring(7)); // output:file not found
10.replace()
Replaces old word with new word.
Example :
String s="I love java";
System.out.println(s.replace("java", "Spring Boot"));
//output:I love Spring Boot
11.matches()
used for pattern checking(like mobile number).**
Example :
String mobile="9876543210";
mobile.matches("\\d{10}"); // output:true
Top comments (1)
Avoid giving ? in Title. Integer.ParseInt is not String method