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authorJake Prather <JakeHP@Zoho.com>2013-06-29 22:12:03 -0500
committerJake Prather <JakeHP@Zoho.com>2013-06-29 22:12:03 -0500
commit4b873348fce636644917b812fbf746f59b56bcc4 (patch)
tree71dc9558cf7337b4e93455f4b10966bb30812384 /java.html.markdown
parentd32bad8aed47e58c4f675d9487537ac42d54004e (diff)
Update java.html.markdown
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diff --git a/java.html.markdown b/java.html.markdown
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---
+
language: java
+
author: Jake Prather
+
author_url: http://github.com/JakeHP
+
---
Java is a general-purpose, concurrent, class-based, object-oriented computer programming language.
Read more here: https://en.wikipedia.org/wiki/Java_(programming_language)
```java
-// Single-line comments start with //
-/*
-Multi-line comments look like this.
-*/
-
-// Import Packages
-import java.util.ArrayList;
-import package.path.here;
-// Import "sub-packages"
-import java.lang.Math.*;
-
-// Your program's entry point is a function called main
-public class Main
-{
- public static void main (String[] args) throws java.lang.Exception
+///////////////////////////////////////
+// General
+///////////////////////////////////////
+ // Single-line comments start with //
+ /*
+ Multi-line comments look like this.
+ */
+
+ // Import Packages
+ import java.util.ArrayList;
+ import package.path.here;
+ // Import all "sub-packages"
+ import java.lang.Math.*;
+
+ // Your program's entry point is a function called main
+ public class Main
{
- //stuff here
+ public static void main (String[] args) throws java.lang.Exception
+ {
+ //stuff here
+ }
}
-}
-
-// Printing
-System.out.println("Hello World");
-System.out.println("Integer: "+10+"Double: "+3.14+ "Boolean: "+true);
+
+ // Printing, and forcing a new line on next print = println()
+ System.out.println("Hello World");
+ System.out.println("Integer: "+10+"Double: "+3.14+ "Boolean: "+true);
+ // Printing, without forcing a new line on next print = print()
+ System.out.print("Hello World");
+ System.out.print("Integer: "+10+"Double: "+3.14+ "Boolean: "+true);
///////////////////////////////////////
// Types
///////////////////////////////////////
-// Byte - 8-bit signed two's complement integer (-128 <= byte <= 127)
-
-// Short - 16-bit signed two's complement integer (-32,768 <= short <= 32,767)
-
-//Integer - 32-bit signed two's complement integer (-2,147,483,648 <= int <= 2,147,483,647)
-int x = 1;
-
-//Long - 64-bit signed two's complement integer (-9,223,372,036,854,775,808 <= long <= 9,223,372,036,854,775,807)
-
-//Float - Single-precision 32-bit IEEE 754 Floating Point
-
-//Double - Double-precision 64-bit IEEE 754 Floating Point
-
-//Boolean - True & False
-
-//Char - A single 16-bit Unicode character
-
-
-// Other than char, which is always 1 byte, these types vary in size depending
-// on your machine. sizeof(T) gives you the size of a variable with type T in
-// bytes so you can express the size of these types in a portable way.
-// For example,
-printf("%d\n", sizeof(int)); // => 4 (on machines with 4-byte words)
-
-// Arrays must be initialized with a concrete size.
-char my_char_array[20]; // This array occupies 1 * 20 = 20 bytes
-int my_int_array[20]; // This array occupies 4 * 20 = 80 bytes
- // (assuming 4-byte words)
-
-
-// You can initialize an array to 0 thusly:
-char my_array[20] = {0};
-
-// Indexing an array is like other languages -- or,
-// rather, other languages are like C
-my_array[0]; // => 0
-
-// Arrays are mutable; it's just memory!
-my_array[1] = 2;
-printf("%d\n", my_array[1]); // => 2
-
-// Strings are just arrays of chars terminated by a NUL (0x00) byte,
-// represented in strings as the special character '\0'.
-// (We don't have to include the NUL byte in string literals; the compiler
-// inserts it at the end of the array for us.)
-char a_string[20] = "This is a string";
-printf("%s\n", a_string); // %s formats a string
-
-/*
-You may have noticed that a_string is only 16 chars long.
-Char #17 is the NUL byte.
-Chars #18, 19 and 20 have undefined values.
-*/
-
-printf("%d\n", a_string[16]); => 0
+ // Byte - 8-bit signed two's complement integer (-128 <= byte <= 127)
+ byte foo = 100;
+
+ // Short - 16-bit signed two's complement integer (-32,768 <= short <= 32,767)
+ short bar = 10000;
+
+ //Integer - 32-bit signed two's complement integer (-2,147,483,648 <= int <= 2,147,483,647)
+ int foo = 1;
+
+ //Long - 64-bit signed two's complement integer (-9,223,372,036,854,775,808 <= long <= 9,223,372,036,854,775,807)
+ long bar = 100000L;
+
+ //Float - Single-precision 32-bit IEEE 754 Floating Point
+ float foo = 234.5f;
+
+ //Double - Double-precision 64-bit IEEE 754 Floating Point
+ double bar = 123.4;
+
+ //Boolean - True & False
+ boolean foo = true;
+ boolean bar = false;
+
+ //Char - A single 16-bit Unicode character
+ char foo = 'A';
+
+ //Strings
+ String foo = "Hello World!";
+ // \n is an escaped character that starts a new line
+ String foo = "Hello World!\nLine2!";
+ System.out.println(foo);
+ //Hello World!
+ //Line2!
+
+ //Arrays
+ //The array size must be decided upon declaration
+ //The format for declaring an array is follows:
+ //<datatype> [] <var name> = new <datatype>[<array size>];
+ int [] array = new int[10];
+ String [] array = new String[1];
+ boolean [] array = new boolean[100];
+
+ // Indexing an array - Accessing an element
+ array[0];
+
+ // Arrays are mutable; it's just memory!
+ array[1] = 1;
+ System.out.println(array[1]); // => 1
+ array[1] = 2;
+ printf("%d\n", my_array[1]); // => 2
+
+ //Others to check out
+ //ArrayLists - Like arrays except more functionality is offered, and the size is mutable
+ //LinkedLists
+ //Maps
+ //HashMaps
///////////////////////////////////////
// Operators
///////////////////////////////////////
-int i1 = 1, i2 = 2; // Shorthand for multiple declaration
-float f1 = 1.0, f2 = 2.0;
-
-// Arithmetic is straightforward
-i1 + i2; // => 3
-i2 - i1; // => 1
-i2 * i1; // => 2
-i1 / i2; // => 0 (0.5, but truncated towards 0)
-
-f1 / f2; // => 0.5, plus or minus epsilon
-
-// Modulo is there as well
-11 % 3; // => 2
-
-// Comparison operators are probably familiar, but
-// there is no boolean type in c. We use ints instead.
-// 0 is false, anything else is true. (The comparison
-// operators always return 0 or 1.)
-3 == 2; // => 0 (false)
-3 != 2; // => 1 (true)
-3 > 2; // => 1
-3 < 2; // => 0
-2 <= 2; // => 1
-2 >= 2; // => 1
-
-// Logic works on ints
-!3; // => 0 (Logical not)
-!0; // => 1
-1 && 1; // => 1 (Logical and)
-0 && 1; // => 0
-0 || 1; // => 1 (Logical or)
-0 || 0; // => 0
-
-// Bitwise operators!
-~0x0F; // => 0xF0 (bitwise negation)
-0x0F & 0xF0; // => 0x00 (bitwise AND)
-0x0F | 0xF0; // => 0xFF (bitwise OR)
-0x04 ^ 0x0F; // => 0x0B (bitwise XOR)
-0x01 << 1; // => 0x02 (bitwise left shift (by 1))
-0x02 >> 1; // => 0x01 (bitwise right shift (by 1))
+ int i1 = 1, i2 = 2; // Shorthand for multiple declarations
+
+ // Arithmetic is straightforward
+ i1 + i2; // => 3
+ i2 - i1; // => 1
+ i2 * i1; // => 2
+ i1 / i2; // => 0 (0.5, but truncated towards 0)
+
+ // Modulo
+ 11 % 3; // => 2
+
+ // Comparison operators
+ 3 == 2; // => 0 (false)
+ 3 != 2; // => 1 (true)
+ 3 > 2; // => 1
+ 3 < 2; // => 0
+ 2 <= 2; // => 1
+ 2 >= 2; // => 1
+
+ // Bitwise operators!
+ ~ Unary bitwise complement
+ << Signed left shift
+ >> Signed right shift
+ >>> Unsigned right shift
+ & Bitwise AND
+ ^ Bitwise exclusive OR
+ | Bitwise inclusive OR
///////////////////////////////////////
// Control Structures
///////////////////////////////////////
-if (0) {
- printf("I am never run\n");
-} else if (0) {
- printf("I am also never run\n");
-} else {
- printf("I print\n");
-}
-
-// While loops exist
-int ii = 0;
-while (ii < 10) {
- printf("%d, ", ii++); // ii++ increments ii in-place, after using its value.
-} // => prints "0, 1, 2, 3, 4, 5, 6, 7, 8, 9, "
-
-printf("\n");
-
-int kk = 0;
-do {
- printf("%d, ", kk);
-} while (++kk < 10); // ++kk increments kk in-place, before using its value
-// => prints "0, 1, 2, 3, 4, 5, 6, 7, 8, 9, "
-
-printf("\n");
-
-// For loops too
-int jj;
-for (jj=0; jj < 10; jj++) {
- printf("%d, ", jj);
-} // => prints "0, 1, 2, 3, 4, 5, 6, 7, 8, 9, "
+ if (false) {
+ System.out.println("I never run");
+ } else if (false) {
+ System.out.println("I am also never run");
+ } else {
+ System.out.println("I print");
+ }
+ }
-printf("\n");
+ // While loops exist
+ int ii = 0;
+ while (ii < 10) {
+ printf("%d, ", ii++); // ii++ increments ii in-place, after using its value.
+ } // => prints "0, 1, 2, 3, 4, 5, 6, 7, 8, 9, "
+
+ printf("\n");
+
+ int kk = 0;
+ do {
+ printf("%d, ", kk);
+ } while (++kk < 10); // ++kk increments kk in-place, before using its value
+ // => prints "0, 1, 2, 3, 4, 5, 6, 7, 8, 9, "
+
+ printf("\n");
+
+ // For loops too
+ int jj;
+ for (jj=0; jj < 10; jj++) {
+ printf("%d, ", jj);
+ } // => prints "0, 1, 2, 3, 4, 5, 6, 7, 8, 9, "
+
+ printf("\n");
///////////////////////////////////////
// Typecasting