java速查手冊Java Syntax Cheatsheet for Algorithms by TCXX

Numbers

static ​MAX_VALUE xxxValue()

public int ​compareTo​(XXX)

public boolean ​equals​(Object o)

static Integer ​valueOf​(int i)

static Integer valueOf(String s)

static Integer valueOf(String s, int radix)

String ​toString​()

static String toString(int i)

static int ​parseInt​(String s)

static int parseInt(String s, int radix)

Math

xxx abs(xxx x)

double​ ceil​(double d) double ceil(float f)

double ​floor​(double d) double floor(float f)

double ​int​(double d)

long ​round​(double d) int round(float f)

double ​exp​(double d)

double ​log​(double d)

double ​pow​(double base, double exponent)

Double E, PI

Strings

char ​charAt​(int index)

int ​indexOf​(char ch)

String ​concat​(String s)

String ​substring​(int beginIndex)

String substring(int beginIndex, int endIndex)

String ​toLowerCase​()

String ​toUpperCase​()

boolean ​contains​(CharSequence s)

static String ​copyValueOf​(char[] data)

char[] ​toCharArray​() int ​length​()

boolean ​contentEquals​(StringBuffer sb)

boolean ​startsWith​(String prefix)

boolean ​endsWith​(String suffix)

boolean ​matches​(String regex)

String ​intern​()

String ​trim​()

String ​replace​(char oldChar, char newChar)

String ​replaceAll​(String regex, String replacement)

String ​replaceFirst​(String regex, String replacement)

String[] ​split​(String regex)

String[] split(String regex, int limit)

static String ​valueOf​(XXX)

Array & ArrayList

int[][] myArr = new int[5][10];

ArrayList<String> myArr=new ArrayList<String>();

myArr.​add​(「dynamically resizing」);

System.out.println(myArr.​get​(0));

Vector

Vector<String> myVect=new Vector<String>();

myVect.​add​(「synchronized」);

System.out.println(「myVect.​get​(0)」);

LinkedList

LinkedList<String> myList=new LinkedList<String>();

myList.​add​(「build-in list」);

Iterator<String> iter=myList.​iterator​();

while (iter.​hasNext​())

System.out.println(iter.​next​());

HashMap

HashMap<String,String> map=new HashMap<String,String>();

map.​put​(「key」,」value」);

System.out.println(map.​get​(「key」));

Regex

String pattern=」(.*(\d+))」;

Pattern r=Pattern.​compile​(pattern);

String line=」lalala」;

Matcher m=r.​matche​r(line);

if(m.​find​()) line=line.​replaceAll​(「-」,」」);

Read with Scanner

Scanner sc=new Scanner(System.in);

while(sc.​hasNextLine​())

System.out.println(sc.​nextLine​());

Read with BufferedReader

String thisLine=null;
try {
        BufferedReader br = new BufferedReader("c:/test.txt");
        while ((thisLine = br.​readLine​()) != null) { System.out.println(thisLine); }
} catch(Exception e) {
    e.printStackTrace();
}

StdIn

boolean​ isEmpty​() int ​readInt​()

boolean ​hasNextChar​()

char ​readChar​()

Int[] ​readAllInts​()

String[] ​readAllLines​()

String ​readAll​()

Arrays

public static void ​fill​(int[] a, int val)

public static void ​sort​(Object[] a)

Enums

boolean ​hasMoreElements​()

Object ​nextElement​()

Stacks

Object ​push​(Object element)

Object ​pop​()

Object ​peek​()

boolean ​isEmpty​()

Queues

Object ​offer​()

Object ​poll​()

boolean ​isEmpty​()

Dictionaries

Object ​put​(Object key, Object value)

Object ​get​(Object key)

Enumeration ​elements​()

Enumeration ​keys​()

Object ​remove​(Object key)

boolean ​isEmpty​()

boolean ​contains​(Object key)

int ​size​()

StringBuilder

StringBuilder ​append​(char c)

StringBuilder ​deleteCharAt​(int index)

int ​length​()

Collections.​sort​(arrayList)