| Java |
Program Structure |
C# | |
| package hello; public class HelloWorld {
public static void main(String[] args) {
String name = "Java";
if (args.length == 1)
name = args[0]; System.out.println("Hello, " + name + "!");
}
} |
using System; namespace Hello {
public class HelloWorld {
public static void Main(string[] args) {
string name = "C#";
if (args.Length == 1)
name = args[0]; Console.WriteLine("Hello, " + name + "!");
}
}
} |
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// Single line
/* Multiple
line */
/** Javadoc documentation comments */ |
// Single line
/* Multiple
line */
/// XML comments on a single line
/** XML comments on multiple lines */ |
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boolean
byte
char
short, int, long
float, double
Object
String
arrays, classes, interfaces
int x = 123;
String y = Integer.toString(x);
y = "456";
x = Integer.parseInt(y);
double z = 3.5;
x = (int) z;
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bool
byte, sbyte
char
short, ushort, int, uint, long, ulong
float, double, decimal
structures, enumerations
object
string
arrays, classes, interfaces, delegates
int x = 123;
String y = x.ToString();
y = "456";
x = int.Parse(y);
double z = 3.5;
x = (int) z;
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// May be initialized in a constructor
final double PI = 3.14; |
const double PI = 3.14;
readonly int MAX_HEIGHT = 9;
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enum Action {Start, Stop, Rewind, Forward};
enum Status {
Flunk(50), Pass(70), Excel(90);
private final int value;
Status(int value) { this.value = value; }
public int value() { return value; }
};
Action a = Action.Stop;
if (a != Action.Start)
System.out.println(a); Status s = Status.Pass;
System.out.println(s.value()); |
enum Action {Start, Stop, Rewind, Forward};
enum Status {Flunk = 50, Pass = 70, Excel = 90};
Action a = Action.Stop;
if (a != Action.Start)
Console.WriteLine(a); Status s = Status.Pass;
Console.WriteLine((int) s); |
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== < > <= >= !=
+ - * /
%
/
Math.Pow(x, y)
= += -= *= /= %= &= |= ^= <<= >>= >>>= ++ --
& | ^ ~ << >> >>>
&& || & | ^ !
Note: && and || perform short-circuit logical evaluations
+
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== < > <= >= !=
+ - * /
%
/
Math.Pow(x, y)
= += -= *= /= %= &= |= ^= <<= >>= ++ --
& | ^ ~ << >>
&& || & | ^ !
Note: && and || perform short-circuit logical evaluations
+
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greeting = age < 20 ? "What's up?" : "Hello";
if (x < y)
System.out.println("greater");
if (x != 100) {
x *= 5;
y *= 2;
}
else
z *= 6;
int selection = 2;
switch (selection) { // Must be byte, short, int, char, or enum
case 1: x++; // Falls through to next case if no break
case 2: y++; break;
case 3: z++; break;
default: other++;
} |
greeting = age < 20 ? "What's up?" : "Hello";
if (x < y)
Console.WriteLine("greater");
if (x != 100) {
x *= 5;
y *= 2;
}
else
z *= 6; string color = "red";
switch (color) { // Can be any predefined type
case "red": r++; break; // break is mandatory; no fall-through
case "blue": b++; break;
case "green": g++; break;
default: other++; break; // break necessary on default
} |
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while (i < 10)
i++; for (i = 2; i <= 10; i += 2)
System.out.println(i); do
i++;
while (i < 10);
for (int i : numArray)
sum += i;
import java.util.ArrayList;
ArrayList<Object> list = new ArrayList<Object>();
list.add(10);
list.add("Bisons");
list.add(2.3);
for (Object o : list)
System.out.println(o); |
while (i < 10)
i++; for (i = 2; i <= 10; i += 2)
Console.WriteLine(i); do
i++;
while (i < 10);
foreach (int i in numArray)
sum += i;
// foreach can be used to iterate through any collection
using System.Collections;
ArrayList list = new ArrayList();
list.Add(10);
list.Add("Bisons");
list.Add(2.3); foreach (Object o in list)
Console.WriteLine(o); |
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int nums[] = {1, 2, 3}; or int[] nums = {1, 2, 3};
for (int i = 0; i < nums.length; i++)
System.out.println(nums[i]);String names[] = new String[5];
names[0] = "David"; float twoD[][] = new float[rows][cols];
twoD[2][0] = 4.5;
int[][] jagged = new int[5][];
jagged[0] = new int[5];
jagged[1] = new int[2];
jagged[2] = new int[3];
jagged[0][4] = 5; |
int[] nums = {1, 2, 3};
for (int i = 0; i < nums.Length; i++)
Console.WriteLine(nums[i]);string[] names = new string[5];
names[0] = "David"; float[,] twoD = new float[rows, cols];
twoD[2,0] = 4.5f;
int[][] jagged = new int[3][] {
new int[5], new int[2], new int[3] };
jagged[0][4] = 5; |
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// Return single value
int Add(int x, int y) {
return x + y;
}
int sum = Add(2, 3); |
// Return no value
void PrintSum(int x, int y) {
System.out.println(x + y);
}
PrintSum(2, 3); |
void TestFunc(int x, Point p) {
x++;
p.x++;
p = null;
}
class Point {
public int x, y;
}
Point p = new Point();
p.x = 2;
int a = 1;
TestFunc(a, p);
System.out.println(a + " " + p.x + " " + (p == null) );
int Sum(int ... nums) {
int sum = 0;
for (int i : nums)
sum += i;
return sum;
}
int total = Sum(4, 3, 2, 1); |
// Return single value
int Add(int x, int y) {
return x + y;
}
int sum = Add(2, 3); |
// Return no value
void PrintSum(int x, int y) {
Console.WriteLine(x + y);
}
PrintSum(2, 3); |
void TestFunc(int x, ref int y, out int z, Point p1, ref Point p2) {
x++; y++; z = 5;
p1.x++;
p1 = null;
p2 = null;
}
class Point {
public int x, y;
}
Point p1 = new Point();
Point p2 = new Point();
p1.x = 2;
int a = 1, b = 1, c;
TestFunc(a, ref b, out c, p1, ref p2);
Console.WriteLine("{0} {1} {2} {3} {4}",
a, b, c, p1.x, p2 == null);
int Sum(params int[] nums) {
int sum = 0;
foreach (int i in nums)
sum += i;
return sum;
}
int total = Sum(4, 3, 2, 1); // returns 10 |
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String school = "Harding ";
school = school + "University";
String mascot = "Bisons";
if (mascot == "Bisons")
if (mascot.equals("Bisons"))
if (mascot.equalsIgnoreCase("BISONS"))
if (mascot.compareTo("Bisons") == 0)
System.out.println(mascot.substring(2, 5));
java.util.Calendar c = new java.util.GregorianCalendar(1973, 10, 12);
String s = String.format("My birthday: %1$tb %1$te, %1$tY", c);
StringBuffer buffer = new StringBuffer("two ");
buffer.append("three ");
buffer.insert(0, "one ");
buffer.replace(4, 7, "TWO");
System.out.println(buffer); |
string school = "Harding ";
school = school + "University";
string mascot = "Bisons";
if (mascot == "Bisons")
if (mascot.Equals("Bisons"))
if (mascot.ToUpper().Equals("BISONS"))
if (mascot.CompareTo("Bisons") == 0)
Console.WriteLine(mascot.Substring(2, 3));
DateTime dt = new DateTime(1973, 10, 12);
string s = "My birthday: " + dt.ToString("MMM dd, yyyy");
System.Text.StringBuilder buffer = new System.Text.StringBuilder("two ");
buffer.Append("three ");
buffer.Insert(0, "one ");
buffer.Replace("two", "TWO");
Console.WriteLine(buffer); |
| Java |
Exception Handling |
C# | |
|
Exception ex = new Exception("Something is really wrong.");
throw ex;
try {
y = 0;
x = 10 / y;
} catch (Exception ex) {
System.out.println(ex.getMessage());
} finally {
} |
Exception up = new Exception("Something is really wrong.");
throw up;
try {
y = 0;
x = 10 / y;
} catch (Exception ex) {
Console.WriteLine(ex.Message);
} finally {
}
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package harding.compsci.graphics;
import harding.compsci.graphics.Rectangle;
import harding.compsci.graphics.*;
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namespace Harding.Compsci.Graphics {
...
}
namespace Harding {
namespace Compsci {
namespace Graphics {
...
}
}
}
using Rectangle = Harding.CompSci.Graphics.Rectangle;
using Harding.Compsci.Graphics;
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| Java |
Classes / Interfaces |
C# | |
|
public
private
protected
static
class FootballGame extends Competition {
...
}
interface IAlarmClock {
...
}
interface IAlarmClock extends IClock {
...
}
class WristWatch implements IAlarmClock, ITimer {
...
}
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public
private
internal
protected
protected internal
static
class FootballGame : Competition {
...
}
interface IAlarmClock {
...
}
interface IAlarmClock : IClock {
...
}
class WristWatch : IAlarmClock, ITimer {
...
}
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| Java |
Constructors / Destructors |
C# | |
|
class SuperHero {
private int mPowerLevel;
public SuperHero() {
mPowerLevel = 0;
}
public SuperHero(int powerLevel) {
this.mPowerLevel= powerLevel;
}
protected void finalize() throws Throwable {
super.finalize();
}
} |
class SuperHero {
private int mPowerLevel; public SuperHero() {
mPowerLevel = 0;
} public SuperHero(int powerLevel) {
this.mPowerLevel= powerLevel;
} ~SuperHero() {
}
} |
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SuperHero hero = new SuperHero();
hero.setName("SpamMan");
hero.setPowerLevel(3); hero.Defend("Laura Jones");
SuperHero.Rest(); SuperHero hero2 = hero;
hero2.setName("WormWoman");
System.out.println(hero.getName()); hero = null; if (hero == null)
hero = new SuperHero();
Object obj = new SuperHero();
System.out.println("object's type: " + obj.getClass().toString());
if (obj instanceof SuperHero)
System.out.println("Is a SuperHero object."); |
SuperHero hero = new SuperHero(); hero.Name = "SpamMan";
hero.PowerLevel = 3; hero.Defend("Laura Jones");
SuperHero.Rest();
SuperHero hero2 = hero;
hero2.Name = "WormWoman";
Console.WriteLine(hero.Name);
hero = null ;
if (hero == null)
hero = new SuperHero();
Object obj = new SuperHero();
Console.WriteLine("object's type: " + obj.GetType().ToString());
if (obj is SuperHero)
Console.WriteLine("Is a SuperHero object."); |
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private int mSize;
public int getSize() { return mSize; }
public void setSize(int value) {
if (value < 0)
mSize = 0;
else
mSize = value;
}
int s = shoe.getSize();
shoe.setSize(s+1);
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private int mSize;
public int Size {
get { return mSize; }
set {
if (value < 0)
mSize = 0;
else
mSize = value;
}
}
shoe.Size++; |
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No structs in Java. |
struct StudentRecord {
public string name;
public float gpa; public StudentRecord(string name, float gpa) {
this.name = name;
this.gpa = gpa;
}
} StudentRecord stu = new StudentRecord("Bob", 3.5f);
StudentRecord stu2 = stu; stu2.name = "Sue";
Console.WriteLine(stu.name);
Console.WriteLine(stu2.name); |
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java.io.DataInput in = new java.io.DataInputStream(System.in);
System.out.print("What is your name? ");
String name = in.readLine();
System.out.print("How old are you? ");
int age = Integer.parseInt(in.readLine());
System.out.println(name + " is " + age + " years old.");
int c = System.in.read();
System.out.println(c);
System.out.printf("The %s costs $%.2f for %d months.%n", "studio", 499.0, 3);
System.out.printf("Today is %tD\n", new java.util.Date());
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Console.Write("What's your name? ");
string name = Console.ReadLine();
Console.Write("How old are you? ");
int age = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("{0} is {1} years old.", name, age);
// or
Console.WriteLine(name + " is " + age + " years old.");
int c = Console.Read();
Console.WriteLine(c);
Console.WriteLine("The {0} costs {1:C} for {2} months.\n", "studio", 499.0, 3);
Console.WriteLine("Today is " + DateTime.Now.ToShortDateString());
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import java.io.*;
FileWriter writer = new FileWriter("c:\\myfile.txt");
writer.write("Out to file.\n");
writer.close();
FileReader reader = new FileReader("c:\\myfile.txt");
BufferedReader br = new BufferedReader(reader);
String line = br.readLine();
while (line != null) {
System.out.println(line);
line = br.readLine();
}
reader.close();
FileOutputStream out = new FileOutputStream("c:\\myfile.dat");
out.write("Text data".getBytes());
out.write(123);
out.close();
FileInputStream in = new FileInputStream("c:\\myfile.dat");
byte buff[] = new byte[9];
in.read(buff, 0, 9);
String s = new String(buff);
int num = in.read();
in.close();
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using System.IO;
StreamWriter writer = File.CreateText("c:\\myfile.txt");
writer.WriteLine("Out to file.");
writer.Close();
StreamReader reader = File.OpenText("c:\\myfile.txt");
string line = reader.ReadLine();
while (line != null) {
Console.WriteLine(line);
line = reader.ReadLine();
}
reader.Close();
BinaryWriter out = new BinaryWriter(File.OpenWrite("c:\\myfile.dat"));
out.Write("Text data");
out.Write(123);
out.Close();
BinaryReader in = new BinaryReader(File.OpenRead("c:\\myfile.dat"));
string s = in.ReadString();
int num = in.ReadInt32();
in.Close();
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