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
