String and its methods

I don’t think there is a need to explain the meaning of string . We can simply name it as a line and I would say that it is much better to use string than char (symbols) as there are more interesting tools and functions for it.
Let’s start!

1. Divide string

Indexof() brings the numeric value as it finds the first position of the entered symbol (or returns -1 if not found). So it can be used together with substring() , which cuts, to divide string and to keep the result also in string. Example:

while (s.indexOf(' ') != -1)
int k = s.indexOf(' ');
s = s.substring(k + 1, s.length());
P.S. length() returns a numeric value (how much symbols does your line have)

2. Divide string Pro

What if we divide string using some pattern? For example we want to spit the words. So we need a mass to keep all the words together.
String[] mas = new string [any length];

Then we have to use split() to delete all " "


String pattern = " ";

mas = line.split(pattern);

If our line=“hello to all programmists” , then we have mas[0]=“Hello”, mas[1]=“to” and so on.

3. Making copies carefully and correctly

Use System.arraycopy()

How to use it?

System.arraycopy(start mas1, first index mas1, result mas2, first index mas2, length);

4. Num check

If you want to convert your string into a numeric value, you can catch a mistake if it is not a num, so you program will work incorrectly. Check with the function if it is a num and only then convert.

public static boolean isNumeric(String strNum) {

try {

long d = Long.parseLong(strNum);


catch (NumberFormatException | NullPointerException nfe) {

return false;


return true;


Other tools are simple for me in usage and don’t need any explanation. If you have any questions, write to me anytime.

Good luck in your job!

Written by Andersenlab

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