1. java-
: Java, , , , , , .
:
1. , ;
2. .
Java , .
:
public class First {
public static void main(String[] args) {
System.out.print ln (" Java!");
}
}
First , main(), Java. main() - String[] args (public) . , main() . static , , . Java , Java C/C++ PHP.
Java! println() (ln ) out System, java.lang. , java. :
javac First.java.
First.class. Java :
java First
.
- NetBeans IDE Java Java ME, Java SE Java EE. Sun Microsystems, Java, Java.
- Eclipse IDE Java SE, Java EE Java ME. IBM, , Java.
- IntelliJ IDEA Java SE, Java EE Java ME. JetBrains. : (Community Edition) (Ultimate Edition).
- JDeveloper Java SE, Java EE Java ME. Oracle.
- JBuilder (IDE) Java, Eclipse.
- BlueJ Java, , .
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System
System . .
, System, , System.out. (, .., , PrintStream, JSDK: http://docs.oracle.com/javase/6/docs/api/):
public static void main(String[] args) {
System.out.println("Study Java");
try {
PrintStream print = new PrintStream(new
FileOutputStream("d:\\file2.txt"));
System.setOut(print);
System.out.println("Study well");
} catch(FileNotFoundException e) {
e.printStackTrace();
}
}
:
Study Java.
"d:\file2.txt" :
Study well.
System.in System.setIn(InputStream) System.err System.setErr ( in, out, err ).
String
String :
- concat(String s) + ;
- equals(Object ob), equalsIgnoreCase(String s) ;
- compareTo(String s), compareToIgnoreCase (String s) ;
- contentEquals(StringBuffer ob) StringBuffer;
- charAt(int n) ( );
- substring(int n, int m)- m-n, n;
- length() ;
- valueOf() ;
- toUpperCase() / toLowerCase() / ;
- replace(char 1, char 2) ;
- getBytes(), getChars() .
String .
public class DemoString {
public static void main(String[] args) {
char s[] = { 'J', 'a', 'v', 'a' };
int i = 2;
//
String str = new String(s); // str ="Java"
i = str.length(); // i=4
String num = String.valueOf(2); // num="2"
str = str.toUpperCase(); // str="Java"
num = str.concat(num); // num="Java2"
str = str + "C";// str="JavaC";
char ch = str.charAt(2); // ch='V'
i = str.lastIndexOf('A'); // i=3 (-1 )
num = num.replace('2', 'H'); // num="JavaH"
i = num.compareTo(str); // i=5 ( 'H' ' ')
str.substring(0, 3).toLowerCase(); // java
}
}
java-
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: n . , .
:
import java.io.IOException;
import java.util.InputMismatchException;
import java.util.Scanner;
public class Main
{
public static void main(String[] args)
{
int n = 0;
while (true) //
{
System.out.println(" ");
Scanner sc1 = new Scanner(System. in);
try
{
n = sc1.nextInt();
break;
}
catch(InputMismatchException fg)
{
//
System.out.print(" . ");
}
}
//
String[] str = new String[n];
Scanner sc2 = new Scanner(System.in);
for (int i = 0; i < n; i++)
{
System. out.println(" " + (i+1));
str[i] = sc2.nextLine();
}
//
for (int i = 0; i < str. length -1; i++)
{
for (int j = i+1; j < str.length; j++)
{
if (str[i].length()<str[j].length())
{
String temp = str[i];
str[i] = str[j];
str[j] = temp;
}
}
}
int maxlength = str[0].length();
System.out.println(" :");
for (int i = 0; i < str. length; i++)
{
System.out.print(str[i]);
for (int j = 0; j < maxlength - str[i].length(); j++)
System.out.print(" ");
System. out.println(" = " + str[i].length());
}
}
}
