Java Programming Classic 300 Examples of learning notes

First, the basic article
1. Do not use the third party to achieve the exchange of two variable values:
Package basic;

Import Java.util.Scanner;

public class Exchangevalue {
public static void Main (string[] args) {
Scanner scan = new Scanner (system.in);
System.out.println ("Please enter the value of variable A:");
Long a = Scan.nextlong ();
System.out.println ("Please enter the value of variable B:");
Long B = Scan.nextlong ();
System.out.println ("a=" + A + "\tb=" + b);
SYSTEM.OUT.PRINTLN ("variable exchange ... \ t");
A = a ^ b;
b = a ^ b;
A = a ^ b;
System.out.println ("a=" + A + "\tb=" + b);
}
}

2. Use XOR or add and decrypt:
Package basic;

Import Java.util.Scanner;

public class Encryption {
public static void Main (string[] args) {
Scanner scan=new Scanner (system.in);
System.out.println ("Please enter an English string or decrypt the string");
String Password=scan.nextline ();
Char[] Array=password.tochararray ();
for (int i=0;i<array.length;++i) {
Array[i]= (char) (array[i]^20000);
}
SYSTEM.OUT.PRINTLN ("Encrypt or decrypt the results as follows:");
System.out.println (new String (array));
}
}

3. Summing with BigDecimal:
Package basic;

Import Java.math.BigDecimal;

public class Factorial {
public static void Main (string[] args) {
BigDecimal sum=new BigDecimal (0.0);
BigDecimal factorial=new BigDecimal (1.0);
int i=1;
while (i<=10) {
Sum=sum.add (factorial);
++i;
Factorial=factorial.multiply (New BigDecimal (1.0/i));
}
System.out.println ("1+1/2!+1/3!+1/4!.... +1/10!=" +sum);
}
}

4.for Loop Print Hollow Diamond:
Package basic;

public class Diamond {
public static void Main (string[] args) {
Printdiamond (6);
}

public static void Printdiamond (int size) {
if (size% 2 = = 0) {
size++;
}
for (int i = 0; i < SIZE/2 + 1; ++i) {
for (int j = SIZE/2 + 1; j > i + 1; j--) {
System.out.print ("");
}
for (int j = 0; J < 2 * i + 1; j + +) {
if (j = = 0 | | j = 2 * i) {
System.out.print ("*");
} else {
System.out.print ("");
}
}
System.out.println ("");
}
for (int i = SIZE/2 + 1; i < size; i++) {
for (int j = 0; J < I-size/2; J + +) {
System.out.print ("");
}
for (int j = 0; J < 2 * size-1-2 * i; j + +) {
if (j = = 0 | | j = 2 * (Size-i-1)) {
System.out.print ("*");
} else {
System.out.print ("");
}
}
System.out.println ("");
}
}
}

5. Monkey Peach problem: A pile of peaches, 5 monkeys successively to, each time evenly divided 5 copies, throw away the extra one, take their share. Ask at least a few peaches, the last one to get a few peaches.
Package basic;

public class Monkeypeach {
public static void Main (string[] args) {
int n = 1;
int m = 0;
int flag = 1;
int monkeynum = 5;
while (true) {
flag = 1;
m = monkeynum * n + 1;
for (int i = monkeynum; I >= 1; i--) {
If ((M% (monkeyNum-1) = = 0)) {
m = m/(monkeyNum-1) * monkeynum + 1;
flag++;
} else {
Break
}
}
if (flag = = Monkeynum)
Break
n++;
}
SYSTEM.OUT.PRINTLN ("Total peaches:" + M);
System.out.println ("The fifth monkey gets the number of peaches:" + N);
}
}

6. Joseph Question:
Package basic;

Import Javax.swing.JOptionPane;

public class Josephus {
public static void Main (string[] args) {
String s;
int N, K, M, N1;
s = Joptionpane.showinputdialog ("Please enter the number of people:");
n = integer.parseint (s);
N1 = n + 1;
s = Joptionpane.showinputdialog ("Please enter the number of the person who started the Count:");
K = Integer.parseint (s);
s = Joptionpane.showinputdialog ("Please enter the death number:");
m = Integer.parseint (s);
int a[] = new Int[n + 1];
A[0] = 0;
System.out.println ("Outgoing person's number:");
for (int i = 1; i < a.length; i++) {
A[i] = 1;
}
for (int i = 1; I <= m; i++) {
if (n = = 1)
Break
else if (i = = m) {
n--;
i = 0;
A[k] = 0;
System.out.print (k + "");
}
do {
k++;
k = k% N1;
} while (A[k]! = 1);
}
System.out.println ("");
SYSTEM.OUT.PRINTLN ("Survivor Number:" + K);
}
}

7. Sudoku Problem:
Package basic;

Import Java.util.Scanner;

public class Sudoku {
public static void Main (string[] args) {
Scanner s = new Scanner (system.in);
System.out.println ("Please enter the number of Sudoku dimensions to be computed (odd numbers greater than 1):");
int x = S.nextint ();
int h = 0;
int L = X/2;
Int[][] A = new int[x][x];
for (int i = 1; I <= x * x; i++) {
A[h][l] = i;
h--;
l++;
if (H < 0 && l >= x) {
H + = 2;
l--;
} else if (H < 0) {
h = x-1;
} else if (l >= x) {
L = 0;
} else if (A[h][l] > 0) {
H + = 2;
l--;
}
}
for (int i = 0; i < x; i++) {
for (int j = 0; J < x; j + +)
System.out.print (A[i][j] + "");
System.out.println ();
}
}
}

8. Convert the number format to a currency string:
Package basic;

Import Java.text.NumberFormat;
Import Java.util.Locale;
Import Java.util.Scanner;

public class Currencyformat {
public static void Main (string[] args) {
Scanner scan = new Scanner (system.in);
System.out.println ("Please enter a currency number:");
Double number = scan.nextdouble ();
NumberFormat format = numberformat.getcurrencyinstance (Locale.china);
System.out.println ("Locale.china:" + format.format (number));
Format = numberformat.getcurrencyinstance (locale.us);
System.out.println ("locale.us:" + format.format (number));
Format = numberformat.getcurrencyinstance (locale.uk);
System.out.println ("locale.uk:" + format.format (number));
}
}

9. Verify the IP address:

Package basic;

Import Java.util.Scanner;

public class IPAddress {
public static void Main (string[] args) {
Scanner sc = new Scanner (system.in);
System.out.println ("Please enter the IP address you want to verify:");
String text = Sc.nextline ();
String info = matches (text);
SYSTEM.OUT.PRINTLN (info);
}

public static string matches (string text) {
if (text = null &&!text.isempty ()) {
String regex = "^ (1\\d{2}|2[0-4]\\d|25[0-5]|[ 1-9]\\d| [1-9]) \\."
+ "(1\\d{2}|2[0-4]\\d|25[0-5]| [1-9]\\d|\\d] \ \. "
+ "(1\\d{2}|2[0-4]\\d|25[0-5]| [1-9]\\d|\\d] \ \. "
+ "(1\\d{2}|2[0-4]\\d|25[0-5]| [1-9]\\d|\\d) $ ";
if (Text.matches (regex)) {
Return text + "is a legitimate IP address! ";
} else {
Return text + "is not a valid IP address! ";
}
}
Return "Please enter the IP address you want to verify!" ";
}
}

Java Programming Classic 300 Examples of learning notes