JavaTips.java

import org.junit.Test;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import static org.hamcrest.CoreMatchers.containsString;
import static org.hamcrest.CoreMatchers.is;
import static org.hamcrest.MatcherAssert.assertThat;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;

public class JavaTips {

  @Test
  public void howToSplitStrings() {
    String input = "hello-to-everyone";

    String[] parts = input.split("-");

    assertThat(parts[0], is("hello"));
    assertThat(parts[1], is("to"));
    assertThat(parts[2], is("everyone"));
  }

  @Test
  public void usingRegexInJava() {
    String input = "Today is 22 September";

    Pattern regex = Pattern.compile("Today is (\\d+) \\w+");

    Matcher matcher = regex.matcher(input);

    assertTrue(matcher.matches());
    assertThat(matcher.group(1), is("22"));
  }

  @Test
  public void convertingStringNumbersToIntegers() {

    String input = "313";
    int number = Integer.parseInt(input);
    assertThat(number + 1, is(314));
  }

  @Test
  public void parsingNonNumbersAsIntegersThrowsException() {
    try {
      String badInput = "word";
      Integer.parseInt(badInput);
      fail("won't get here");
    } catch (NumberFormatException nfe) {
      assertThat(nfe.getMessage(), containsString("word"));
    }
  }
}