动手动脑：
1.java类中不用static还能如何调用函数
方法调用：“类名.方法”
如果此函数是动态的，那么只有在调用的时候才会被主动加载一次，之后释放内存。方法调用：必须先实例化出来一个类，之后再通过实例化类名+方法的形式调用。
2.观察以下代码的不同之处
表示方法为静态，在其他类中可以用类名去调用这个方法。
课后作业：
1.求组合数源程序：
1）递归求组合数：
import java.util.Scanner; public class Czuhe { public static void main(String[] args) { System.out.print("请输入N："); @SuppressWarnings("resource") Scanner sc=new Scanner(System.in); int N=sc.nextInt(); System.out.print("请输入k："); @SuppressWarnings("resource") Scanner scan=new Scanner(System.in); int K=scan.nextInt(); System.out.println(Cal(N,K)); } public static int Cal(int N,int K) { if(K == 0 || N == 0) { return 1; } if(N < K) { return 0; } if(N == K) { return 1; } return Cal(N-1,K) + Cal(N-1,K-1); } }
（2）利用杨辉三角求组合数：
import java.util.Scanner; @SuppressWarnings("unused") public class Czuhe { public static void main(String[] args) { System.out.print("请输入N："); @SuppressWarnings("resource") Scanner sc=new Scanner(System.in); int N=sc.nextInt(); System.out.print("请输入k："); @SuppressWarnings("resource") Scanner scan=new Scanner(System.in); int K=scan.nextInt(); System.out.println(Cal(N,K)); } public static int Cal(int N,int K) { if(K == 0 || N == 0) { return 1; } int c=0;int a=1; int s=Math.min(K, N-K); for(int i=1;i<=s;i++) { c=a*(N-i+1)/(i); a=c; } return c; } }
（3）使用组合数公式计算：
import java.util.Scanner; @SuppressWarnings("unused") public class Czuhe { public static void main(String[] args) { System.out.print("请输入N："); @SuppressWarnings("resource") Scanner sc=new Scanner(System.in); int N=sc.nextInt(); System.out.print("请输入k："); @SuppressWarnings("resource") Scanner scan=new Scanner(System.in); int K=scan.nextInt(); System.out.println(jiecheng(N)/(jiecheng(K)*jiecheng(N-K))); } public static int jiecheng(int N) { int s=1; if(N == 1) { return 1; } else s=jiecheng(N-1)*N ; return s; } }
2.回文数程序：
import java.util.Scanner; @SuppressWarnings("unused") public class HuiWen { int n=100; public static void main(String[] args) { System.out.print("请输入字符串："); @SuppressWarnings("resource") Scanner sc=new Scanner(System.in); String N=sc.nextLine(); if(fun(N)==1) System.out.print("是回文字符串！"); else System.out.print("不是回文字符串！"); } public static int fun( String str) { int len=str.length(); { if (len == 0 || len == 1) return 1; char first=str.charAt(0); char last=str.charAt(len-1); if ( first!= last) return 0; return fun(str.substring(1,len-1)); } } }
3.线性同余法生成随机数
import java.util.Date; import java.util.concurrent.atomic.AtomicLong; public class Random { private final AtomicLong seed; private final static long multiplier = 0x5DEECE66DL; private final static long addend = 0xBL; private final static long mask = (1L << 48) - 1; private static volatile long seedUniquifier = 8682522807148012L; public void srandSeed(long t){ this.seed.set(t); } public Random(){ this(++seedUniquifier + System.nanoTime()); System.out.println(seed.get()); } public Random(long seed) { this.seed = new AtomicLong(0L); srandSeed(seed); } int random(int bits){ long oldseed = seed.get(); long nextseed = (oldseed * multiplier + addend) & mask; return (int)(nextseed >>> (48 - bits)); } public static void main(String[] args) { Random r = new Random(); r.srandSeed(new Date().getTime()); System.out.println(r.random(32)); } }
4.汉诺塔程序
import java.util.Scanner; public class TowersOfHanoi { public static void solveTowers( int disks, int sourcePeg, int destinationPeg, int tempPeg ) { if ( disks == 1 ) { System.out.printf( "\n%d --> %d", sourcePeg, destinationPeg ); return; } solveTowers( disks - 1, sourcePeg, tempPeg, destinationPeg ); System.out.printf( "\n%d --> %d", sourcePeg, destinationPeg ); solveTowers( disks - 1, tempPeg, destinationPeg, sourcePeg ); } public static void main( String[] args ) { System.out.print("请输入要移动的盘子数："); @SuppressWarnings("resource") Scanner sc=new Scanner(System.in); @SuppressWarnings("unused") int N=sc.nextInt(); solveTowers( N, 1, 2, 3 ); } }
原文：http://www.cnblogs.com/muxiaozhou/p/5966025.html