comp102 lec 9
TRANSCRIPT
STRINGS
String class
The String class represents character strings. All string literals in Java programs, such as "abc", are implemented as instances of this class.
Strings are constant; their values cannot be changed after they are created.
For example:String str = "abc"; is equivalent to:char data[] = {'a', 'b', 'c'};String str = new String(data);
MethodsThe class String includes methods for
examining individual characters of the sequence, for comparing strings, for searching strings, for extracting substrings, and for creating a copy of a stringwith all characters translated to uppercase or to
lowercase
ConcatenationString name = “Saira";String introduction = "Hello there, my name is " + name;concat(String str)Concatenates the specified string to the end of this string.public class test
{
public static void main(String [] args)
{
String str = "hello";
String str1 = "World";
String str2=str.concat(str1);
System.out.println(str2);
}
}
Character at given position
getting the character at a given position within the string -- charAt()
public class test{
public static void main(String [] args){
String str = "hello";char c= str.charAt(1);System.out.print(c);
}}
getting the number of characters in a string -- length()
public class test{
public static void main(String [] args){
String str = "hello";int x= str.length();System.out.print(x);
}}
extracting a substring from a string -- substring()
public class test{
public static void main(String [] args){
String str = "hello World";String str1= str.substring(2,8);System.out.print(str1);
}}
Compare two strings for equality – equals()
public class test{
public static void main(String [] args){
String str = "hello";String str1 ="hello";System.out.println(str.equals(str1));
}}
Compare two strings – compareTo()
=0 indicate equality>0 indicate calling string follows argument string<0 indicate calling string precedes argument string
public class test{
public static void main(String [] args){
String str = "hello";String str1 ="abcde";System.out.println(str.compareTo(str1));
}}
Tests if this string ends with the specified suffix.
public class test{
public static void main(String [] args){
String str = "hello world";String str1 ="ld";System.out.println(str.endsWith(str1));
}}
Replacing all occurrences of oldChar in string with newChar
public class test{
public static void main(String [] args){
String str = "hello world";String str1 = str.replace('l','x');System.out.println(str1);
}}
Converts String to character arraypublic class test{
public static void main(String [] args){
String str = "hello world";char []array =str.toCharArray();System.out.println(array);System.out.println(array[0]);
}}
Converts all characters to lowercase or uppercase
public class test{
public static void main(String [] args){
String str = "hello world";String str1 = str.toUpperCase();String str2= "HHHElloooo";String str3 = str2.toLowerCase();System.out.println(str1);System.out.println(str3);
}}