ACM Contest Java Programming Summary

1. Length of the string

String str = new String ("ABCD");

int length = Str.length ();

2. Length of the array

2.1 for a[][] A.length represents the number of rows of a a[i].length represents a column count of 2.2 for a[] A.length represents the length of a

3. Conversion of strings and character arrays

String str = new String ("ABCD");

char [] a = Str.tochararray ();

4. Conversion of string numbers and numbers

4.1 String->int

String str = "1234";

int i = integer.parseint (str); An exception may be thrown, (if an error) is appended to main (string[] args) with throws Exception

4.2 int->string

int i=235;

String s = string.valueof (i); of uppercase

5. Importing data from an. in file

Import java. io.*;

public static void Main (String [] args) throws IOException{//throws an exception

FileReader a = new FileReader ("d-small-attempt1.in");//file and source in the same directory
BufferedReader read = new BufferedReader (a);
String textline= "";
String str= "";
while ((Textline=read.readline ())!=null) {
Str+=textline+ "";
}
String[] numbersarray=str.split(""); Separates Str into a character array by a space

}

6. Guide data to a. txt file

Import java. io.*;

FileWriter FW = new FileWriter ("output.txt");
BufferedWriter BUFW = new BufferedWriter (FW);
String line = null;
for (int i=1;i<n+1;i++) {
Bufw.write ("Case #" +i+ ":" +result[i]);
bufw.newline (); Next line
Bufw.flush (); Update
}
Bufw.close ();

7. Reserved limited decimal places

Import java.text.*

DecimalFormat sim = new DecimalFormat ("0.000000");//reserved How many digits after the decimal point there are several
Double six = Sim.format (source); Keep Source Six decimal places

A simpler approach (preserving a limited number of decimal places for output results)

System.out.printf ("%.3f", a);

ACM Contest Java Programming Summary