Java String

My cheat sheet of string related functions. I’ll add more along the way when I use more of it.

Comparison

String one   = "hello";
String two   = "world";
String three = "hello";
String four  = new String("hello");
String five  = "HELLO"
System.out.println(one==two);   # false
System.out.println(one==three); # true
System.out.println(one==four);  # false
# best to use this
System.out.println(one.equals(two));             # false
System.out.println(one.equals(three));           # true
System.out.println(one.equals(four));            # true
System.out.println(one.equalsIgnoreCase(five));  # true

String To Char Array

# string to char array
String hw = "hello world";
char[] ca = hw.toCharArray();
# print the array
for(char c:ch){
  System.out.println(c);
}

Char To ASCII Number

# convert char to ASCII number
System.out.println((int)'A');

Char To String

# char to string
char c = 'A';
String s = String.valueOf(c);
System.out.println(s);

To Lower/Upper Case

String hw = "Hello World";

# to lower case
System.out.println(hw.toLowerCase());
# to upper case
System.out.println(hw.toUpperCase());

Substring

# substring params are start index, end index
String hw = "hello world";
System.out.println(hw.substring(6,7));    # w

Reverse

String s = "hello world";
char[] ca = s.toCharArray();
ArrayList<String> al = new ArrayList<String>();
for(char c:ca){
    al.add(String.valueOf(c));
}
Collections.reverse(al);
System.out.println(String.join("",al));

Split

String s = "the!quick@brown#fox$jumps%over^the&lazy dog";
String[] a = s.split("[!@#$%^& ]");
for(String z:a){
    System.out.println(z);
}

String To Integer

String s = "88";
int i = Integer.parseInt(s);
System.out.println(i);

< Back to all the stories I had written