1. How to compare strings? Use “==” or use equals()?
2. Why is char[] preferred over String for security sensitive information?
3. Can we use string for switch statement?
// java 7 only!
switch (str.toLowerCase()) {
case "a":
value = 1;
break;
case "b":
value = 2;
break;
}
4. How to convert string to int?
int n = Integer.parseInt("10");
5. How to split a string with white space characters?
String[] strArray = aString.split("\\s+");
6. Does substring() method create a new string?
str.substring(m, n) + ""
7. String vs StringBuilder vs StringBuffer
8. How to repeat a string?
String str = "abcd";
String repeated = StringUtils.repeat(str,3);
//abcdabcdabcd
9. How to convert string to date?
String str = "Sep 17, 2013";
Date date = new SimpleDateFormat("MMMM d, yy", Locale.ENGLISH).parse(str);
System.out.println(date);
//Tue Sep 17 00:00:00 EDT 2013
10. How to count # of occurrences of a character in a string?
int n = StringUtils.countMatches("11112222", "1");
System.out.println(n);
A method to detect if string contains only uppercase letter in Java
public static boolean testAllUpperCase(String str){
for(int i=0; i < str.length(); i++){
char c = str.charAt(i);
if(c >= 97 && c <= 122) {
return false;
}
}
//str.charAt(index)
return true;
}
Source:
http://www.programcreek.com/
