Java Examples
Dave Braunschweig
Strings
// This program demonstrates string functions. class Main { public static void main(String[] args) { String str = "Hello"; System.out.println("string: " + str); System.out.println("string.toLowerCase(): " + str.toLowerCase()); System.out.println("string.toUpperCase(): " + str.toUpperCase()); System.out.println("string.indexOf('e'): " + str.indexOf('e')); System.out.println("string.length(): " + str.length()); System.out.println("string.replace('H', 'j'): " + str.replace('H', 'j')); System.out.println("string(substring(2,4): " + str.substring(2, 4)); System.out.println("string.trim(): " + str.trim()); String name = "Bob"; double value = 123.456; System.out.println(String.format("%s earned $%.2f", name, value)); } }
Output
string: Hello string..toLowerCase(): hello string.toUpperCase(): HELLO string.indexOf('e'): 1 string.length(): 5 string.replace('H', 'j'): jello string(substring(2,4): ll string.trim(): Hello Bob earned $123.46
Files
// This program demonstrates reading a text file with exception handling. // References: // https://en.wikibooks.org/wiki/Java_Programming import java.util.*; class Main { public static void main(String[] args) { String FILENAME = "temperature.txt"; readFile(FILENAME); } private static void readFile(String filename) { try { java.io.File file = new java.io.File(filename); java.io.BufferedReader reader = new java.io.BufferedReader(new java.io.FileReader(file)); String line; while(true) { line = reader.readLine(); if (line == null) { break; } System.out.println(line); } reader.close(); System.out.println(""); } catch(Exception exception) { System.out.println("Error reading " + filename); exception.printStackTrace(); } } }
Output
Celsius,Fahrenheit 0,32 10,50 20,68 ... 80,176 90,194 100,212