Learn Java Part 6

Learn Java Part 6

• 1.
  String Functions
• 2.
  • String concat(Stringstr)- Concat string str to given string, and returns the concated string. String s=“Hello”; s.concat(“ Java”); //s will not be updated System.out.print(s); will print Hello System.out.print(s.concat(“ Java”)); will print Hello Java s=s.concat(“ Java”); //now s will be updated System.out.print(s); will print Hello Java
• 3.
  • int length()-returns the length of string String s=“Hello”; int len=s.length(); System.out.print(len); will print 5 • String trim()- removes the spaces from start and end String s=“ hello ”; s.trim(); //s will not be affected System.out.print(s); will print: Hello (with spaces) System.out.print(s.trim()); will print: Hello (Without spaces) s=s.trim(); //now s will be affected System.out.print(s); will print: Hello (Without spaces)
• 4.
  • String toUpperCase()-returns the string with all characters in Upper Case String s=“Hello”; s.toUpperCase(); //s will not be affected System.out.print(s); will print Hello System.out.print(s.toUpperCase()); will print HELLO s=s.toUpperCase(); //now s will be affected System.out.print(s); will print HELLO
• 5.
  • String toLowerCase()-returns the string with all characters in Lower Case String s=“Hello”; s.toLowerCase(); //s will not be affected System.out.print(s); will print Hello System.out.print(s.toLowerCase()); will print hello s=s.toLowerCase(); //now s will be affected System.out.print(s); will print hello
• 6.
  • Boolean isEmpty()-returns true if string is empty, and returns false if string is not empty String s=“Hello”; System.out.print(s.isEmpty()); will print false String s=“”; System.out.print(s.isEmpty()); will print true • Boolean startsWith(String str)- returns true if given string starts with string str, and returns false if given string do not starts with string str String s=“Hello”; System.out.print(s.startsWith(“H”)); will print true System.out.print(s.startsWith(“G”)); will print false
• 7.
  • Boolean endsWith(Stringstr)- returns true if given string ends with string str, and returns false if given string do not ends with string str String s=“Hello”; System.out.print(s.endsWith(“elo”)); will print true System.out.print(s.startsWith(“HH”)); will print false • Boolean equals(String str)- returns true if all characters of given string is equal to all characters of str String s1=“Hello”; String s2=“Hello”; System.out.print(s1. equals(s2)); will print true
• 8.
  • Boolean equalsIgnoreCase(Stringstr)- returns true if all characters of given string is equal to all characters of str by ignoring the case String s1=“Hello”; String s2=“HELLO”; System.out.print(s1. equalsIgnoreCase(s2)); will print true • String replace(char oldCharacter, char newCharacter)- replace the all occurrence of oldCharacter with newCharacter String s1=“Hello”; System.out.print(s1. replace(‘l’,’$’)); will print He$$o To update s1 we have to assign it: s1=s1. replace(‘l’,’$’);
• 9.
  • Boolean equalsIgnoreCase(Stringstr)- returns true if all characters of given string is equal to all characters of str by ignoring the case String s1=“Hello”; String s2=“HELLO”; System.out.print(s1. equalsIgnoreCase(s2)); will print true • String replace(char oldCharacter, char newCharacter)- replace the all occurrence of oldCharacter with newCharacter String s1=“Hello”; System.out.print(s1. replace(‘l’,’$’)); will print He$$o To update s1 we have to assign it: s1=s1. replace(‘l’,’$’);
• 10.
  • String replace(StringoldString, String newString)- replace the all occurrence of oldString with newString String s1=“Hello”; System.out.print(s1. replace(“ll” , ”%”)); will print He%o To update s1 we have to assign it: s1=s1. replace(“ll” , ”%”); • String substring(int start)- returns substring from ‘start’ index. ‘start’ is included. String s1=“ABCDEF”; System.out.print(s1. substring(3)); will print DEF • String substring(int start,int end)- returns substring from ‘start’ index to ‘end’ indes. ‘start’ is included while ‘end’ is exculded String s1=“ABCDEF”; System.out.print(s1. substring(2,5)); will print CDE
• 11.
  • char charAt(intindex) – returns the character at given index String s1=“ABCDEFG”; System.out.print(s1.charAt(3)); will print D • int indexOf(char ch)- returns the first index of given character int indexOf(String str)- returns the first index from where given string starts int indexOf(char ch,int start)- returns the first index of given character after the start index. start is included int indexOf(String str,int start)- returns the first index from where given string starts after the start index. start is included String s1=“ABCDEFABCDEF”; System.out.print(s1. indexOf(‘B’)); will print 1 System.out.print(s1. indexOf(‘B’,5)); will print 7
• 12.
  • int lastIndexOf(charch)- returns the last index of given character int lastIndexOf (String str)- returns the last index from where given string starts int lastIndexOf (char ch,int last)- returns the last index of given character before the last index. last is included int lastIndexOf(String str,int last)- returns the last index from where given string starts before the last index. last is included String s1=“ABCDEFABCDEF”; System.out.print(s1. lastIndexOf(‘B’)); will print 7 • Boolean contains(String str)- returns true if string str is present in given string String s1=“ABCDEFABCDEF”; System.out.print(s1. contains(“ABC”)); will print true
• 13.
  • int compareTo(Stringstr)- compares the string str with given string String s1=“ABC”; String s2=“abc”; System.out.print(s1.compareTo(s2)); will print -32 • int compareToIgnoreCase(String str)- compares the string str with given string by ignoring the case String s1=“ABC”; String s2=“abc”; System.out.print(s1.compareToIgnoreCase(s2)); will print 0 • char[] toCharArray()- converts the string to array of characters String s1=“ABC”; char ch[]=s1.toCharArray(); System.out.print(ch[2]); will print C
• 14.
  • byte[] toByteArray()-converts the string to array of bytes String s1=“ABC”; byte ch[]=s1.toByteArray(); System.out.print(ch[0]); will print 65 • String[] split(String str)- splits the given string to string array. Splits after str String s1=“Hello World”; String ch[]=s1.split(“ “); System.out.print(ch[0]); will print Hello