我這裏保留了，從學習java第壹天起到現在 學習練習代碼，
基礎部分註釋很詳細。
//每壹位相加求和
public class Demo
{
public static void main(String[] args)
{
int i = 45678;
int sum = 0;
int c = 0;
for(int j = 4; j >= 0; j--)
{
int b = (int) Math.pow(10, j);
c = i / b;
System.out.println(c);
sum += c;
System.out.println("sum=" + sum);
i %= b;
}
System.out.println(sum);
}
}
public class ZY1030
{
public static void main(String[] asgs)
{
zy1();
zy2();
zy3();
zy4();
zy5();
zy6();
zy7();
yanghuisanjiao();
}
public static void yanghuisanjiao()
{
int[][] pas = new int[6][];
for(int i = 0; i < pas.length; i++)
{
pas[i] = new int[i + 1];
pas[i][0] = 1;
pas[i][i] = 1;
for(int j = 0; j < pas[i].length - 1; j++)
{
if(j >= 1 && i > 1)
pas[i][j] = pas[i - 1][j - 1] + pas[i - 1][j];
}
}
for(int i = 0; i < pas.length; i++)
{
for(int j = 0; j < pas[i].length; j++)
{
System.out.print(pas[i][j]);
System.out.println();
}
}
System.out.println();
}
private static void zy1()
{
System.out.println("1");
/*
*
**
***
****
*****
******
*******
*/
for(int r = 0; r < 7; r++)
{
for(int j = 0; j < r + 1; j++)
{
System.out.print("*");
}
System.out.println();
}
}
private static void zy2()
{
System.out.println("\n2");
/*
*
***
*****
*******
*********
*/
for(int r = 0; r <= 5; r++)
{
for(int j = 0; j < 11 - r; j++)
{
System.out.print(" ");
}
for(int j = 0; j < r * 2 + 1; j++)
{
System.out.print("*");
}
System.out.println();
}
}
private static void zy3()
{
System.out.println("\n3");
/*
*
* *
* * *
* * * *
* * * * *
*/
for(int r = 0; r <= 5; r++)
{
for(int j = 0; j < 10 - r; j++)
{
System.out.print(" ");
}
for(int j = 0; j < r; j++)
{
System.out.print("* ");
}
System.out.println();
}
}
private static void zy4()
{
System.out.println("\n4");
/*
***********
***********
***********
***********
***********
*/
for(int r = 0; r <= 5; r++)
{
for(int j = 0; j < 7 - r; j++)
{
System.out.print(" ");
}
for(int j = 0; j < 10; j++)
{
System.out.print("*");
}
System.out.println();
}
}
private static void zy5()
{
System.out.println("\n5");
/*
1X1=1
1X2=2 2X2=4
1X3=3 2X3=6 3X3=9
....
*/
for(int r = 1; r <= 9; r++)
{
for(int j = 1; j <= r; j++)
{
int iValue = j * r; //?
String str = j + "X" + r + "=" + iValue + " ";
System.out.print(str);
//System.out.print(" J:" + j);
}
System.out.println();
//System.out.println("R:" + r);
}
}
private static void zy6()
{
System.out.println("\n6");
/*
?() 1?
3 5 7 11 13 17 19 23 ....
int n = 4;
boolean t = true; // assume is SU_SHU
for(int i=2; i<n; i++)
{
if(n%i==0)
{
t = false;
break;
}
}
System.out.println(t);
*/
for(int i = 2; i <= 100; i++)
{
// if(i % 2 ==0 || i % 3 == 0 )
// {
// continue;
// }
// System.out.print(i + " ");
boolean bTrue = true;
for(int j = 2; j < i; j++)
{
if(i % j == 0)
{
bTrue = false;
break;
}
}
if(bTrue)
{
System.out.println(i);
}
}
System.out.println();
}
private static void zy7()
{
System.out.println("\n7");
/*
int n = 23623;
int x = n % 100000 / 10000;
System.out.println(x);
x = n % 10000 / 1000;
System.out.println(x);
x = n % 1000 / 100;
System.out.println(x);
*/
}
}