Java基础练习及代码.docx

Java练习及作业代码集目录一、第一章31.制作九九乘法表32.从键盘输入33.判断一个数是否为素数34.把数字倒着输出45.水仙花数46.判断年份是否为闰年57.输入三边求三角形面积58.一位数加法问答59.空格和星星610.Swich语句控制抽牌711.1000以内的完数712.形如3+33+333+3333单双重循环练习813.求一组随机数最大值914.随机产生十五个不重复的学号915.插入排序1016.选择排序1117.从前往后进行冒泡排序1218.从后往前进行冒泡排序1219.冒泡排序（可提前结束排序）1320.二维数组输出练习1421.上三角和下三角练习1522.偶数列小到大输出，奇数列大到小输出1623.数组方式随机抽取4张牌1724.二维数组输出类似杨辉三角1725.两个矩阵相乘1826.函数调用练习1927.鞍点（1）2028.鞍点（2）2129.打印电话号码22二、第二章221.类，对象和构造方法222.普通方法的重构233.类的继承244.抽象类和抽象方法255.接口266.二分查找287.全排列（递归）29一、 第一章1. 制作九九乘法表public static void main(String args )/九九乘法表for (int r=1;r=9;r+)for(int c=1;c=1;r-)for(int c=1;c=r;c+)System.out.print(r+*+c+=+r*c+t);System.out.println();2. 从键盘输入import java.util.*;public class MyInport public static void main(String args) Scanner sc = new Scanner(System.in); int i=sc.nextInt(); float f=sc.nextFloat(); double d=sc.nextDouble(); System.out.println(i=+i); System.out.println(f=+f); System.out.println(d=+d);3. 判断一个数是否为素数package test;import java.util.*;public class SushuTest public static void main(String args) Scanner sc = new Scanner(System.in);int Ss = sc.nextInt();boolean s = true;for (int i = 2; i 0) System.out.print(sr%10); sr=sr/10;5. 水仙花数package test;public class SXHS public static void main(String args) / TODO Auto-generated method stubSystem.out.print(水仙花数有:);for (int sr = 100; sr c & a + c b & b + c a) double Zc_half = (a + b + c) / 2;double Area = Math.sqrt(Zc_half * (Zc_half - a) * (Zc_half - b) * (Zc_half - c);System.out.print(三角形的面积为: + Area);elseSystem.out.print(无法构成三角形);8. 一位数加法问答import java.util.*;public class YWSJF public static void main(String args) int number1=(int)(Math.random()*10);int number2=(int)(Math.random()*10);Scanner input= new Scanner(System.in);System.out.print(number1+number2+=);int answer=input.nextInt();if(answer=number1+number2)System.out.println(恭喜你，答对了！);elseSystem.out.println(很遗憾，答错了！);System.out.println(number1+number2+=+(number1+number2);9. 空格和星星package mine;public class PrintStar public static void main(String args) int t=9;for (int i = 1; i = t; i+) for (int j = 1; j = t - i; j+) System.out.print( );for (int k = 1; k = 2 * i - 1; k+) System.out.print(*);System.out.println();for(int i=1;it;i+)for(int j=1;j=2*i-1;k-)System.out.print(*);System.out.println();10. Swich语句控制抽牌package mine;public class a public static void main(String args) int card = (int) (Math.random() * 54);String suit = , rank = ;switch (card / 13) case 0:suit = 黑桃;break;case 1:suit = 红桃;break;case 2:suit = 方块;break;case 3:suit = 梅花;break;switch(card%13)case 0:rank = A;break;case 10:rank = J;break;case 11:rank = Q;break;case 12:rank = K;break;default: rank=+(card%13+1);System.out.print(你抽到的牌是:+suit+ +rank);11. 1000以内的完数package mine;public class WanShu public static void main(String args) for (int i = 1; i = 1000; i+) int sum = 0;for (int j = 1; j i; j+) if (i % j = 0) sum = sum + j;if (sum = i) System.out.println(i);12. 形如3+33+333+3333单双重循环练习import java.util.*;public class Test public static void main(String args) / 3+33+333System.out.println(please input a and n);Scanner sc = new Scanner(System.in);int a = sc.nextInt();int n = sc.nextInt();/ 一重循环int sum1 = 0;int term1 = 0;for (int i = 1; i = n; i+) term1 = term1 * 10 + a;sum1 = sum1 + term1;System.out.println(一重循环结果： + sum1);/ 二重循环int sum2 = 0;for (int i = 1; i = n; i+) int term2 = 0;for (int j = 1; j = i; j+) term2 = term2 * 10 + a;sum2 = sum2 + term2;System.out.println(双重循环结果： + sum2);13. 求一组随机数最大值package mine;import java.util.*;public class Test public static void main(String args) Random rad=new Random();int arr=new int 10;for (int i=0;i10;i+)arri=rad.nextInt(100);System.out.print(arri+ );System.out.println();int max=arr0;for(int i=1;i10;i+)if(maxarri)max=arri;System.out.println(the max is:+max);14. 随机产生十五个不重复的学号package aaa;import java.util.*;public class Test public static void main(String args) Random rad=new Random();int arr=new int 15;/产生一个数组，把n放入int k=0;/数组元素的个数for(int i=0;i15;i+)int n=rad.nextInt(47)+1;/产生1-47个学号boolean b=true;for(int j = 0;jk;j+)if(n=arrj)b=false;break;if(b=true)/数字有效无重复，输出并放入数组，个数加一System.out.println(n);arrk=n;k+;elsei-;/数字重复，则使用i-把此循环无效15. 插入排序import java.util.*;public class Test public static void main(String args) / 插入排序Random rand=new Random();int arr =new int10;/放入10个元素int temp;/用于保存当前使用的某元素/生成10个随机数for(int i=0;iarr.length;i+)arri=rand.nextInt(40);/生成0-39内的随机数System.out.print(arri+ );System.out.println();/把数组分成已排序和未排序两部分，进行插入排序for(int i=1;i0;j-)/如 20 1 13temp=arrj;/保存当前未排序的第一个元素if(temparrj-1)arrj=arrj-1;arrj-1=temp;elsebreak;arrj-1=temp;System.out.println(结果如下：);/输出结果for(int i=0;iarr.length;i+)System.out.print(arri+ );16. 选择排序package aa;import java.util.Random;public class Test public static void main(String args) / 选择排序Random rand = new Random();int arr = new int10;/ 放入10个元素int minIndex;/ 生成10个随机数for (int i = 0; i arr.length; i+) arri = rand.nextInt(40);/ 生成0-39内的随机数System.out.print(arri + );System.out.println();for (int i = 0; i arr.length-1; i+) minIndex = i;/内循环找最小的数的位置for (int j = i + 1; j = arr.length-1; j+) if (arrj arrminIndex) minIndex = j;if (minIndex != i) int t = arri;arri = arrminIndex;arrminIndex = t;System.out.println(结果如下：);/ 输出结果for (int i = 0; i arr.length; i+) System.out.print(arri + );17. 从前往后进行冒泡排序package aa;import java.util.Random;public class Test public static void main(String args) / TODO Auto-generated method stub/ 冒泡排序Random rand = new Random();int arr = new int10;/ 放入10个元素/ 生成10个随机数for (int i = 0; i arr.length; i+) arri = rand.nextInt(40);/ 生成0-39内的随机数System.out.print(arri + );System.out.println();for (int i = 0; i arr.length-1; i+) /内层循环控制第i次，每两个元素，两两比较进行交换for(int j=0;jarrj+1)int t=arrj;arrj=arrj+1;arrj+1=t;System.out.println(结果如下：);/ 输出结果for (int i = 0; i arr.length; i+) System.out.print(arri + );18. 从后往前进行冒泡排序import java.util.*;public class Test public static void main(String args) / TODO Auto-generated method stub/ 从后往前冒泡排序Random rand = new Random();int arr = new int10;/ 放入10个元素/ 生成10个随机数for (int i = 0; i 10; i+) arri = rand.nextInt(40);/ 生成0-39内的随机数System.out.print(arri + );System.out.println();for (int i = 0; i 0; j-) if (arrj arrj - 1) int t = arrj;arrj = arrj - 1;arrj - 1 = t;System.out.println(结果如下：);/ 输出结果for (int i = 0; i 10; i+) System.out.print(arri + );19. 冒泡排序（可提前结束排序）import java.util.*;public class Test public static void main(String args) Random rand = new Random();int arr = new int10;/ 放入10个元素/ 生成10个随机数int arr1 = new int10;for (int i = 0; i arr.length; i+) arri = rand.nextInt(40);/ 生成0-39内的随机数System.out.print(arri + );System.out.println();/ 冒泡排序for (int i = 0; i arr.length - 1; i+) boolean flag = true;/ 假设已经排好顺序for (int j = 0; j arrj + 1) / 若前后两个元素对调则排序未完成，将flag设为falseint t = arrj;arrj = arrj + 1;arrj + 1 = t;flag = false;/ 若排序提前完成跳出循环if (flag) System.out.println(第+(i+1)+轮时已经完成排序，跳出循环);break;/ 将每轮结果输出System.out.println(第 + (i+1) + 轮排序);for (int u = 0; u arr.length; u+) arr1u = arru;System.out.print(arru + );System.out.println();System.out.println(结果如下：);for (int i = 0; i arr.length; i+) System.out.print(arri + );20. 二维数组输出练习public class Test public static void main(String args) /按每行，从小到大排int arr=new int44;int k=1;for(int row=0;row4;row+)for(int col=0;col4;col+)arrrowcol=k;System.out.print(arrrowcol+t);k+;System.out.println();/按每列，从小到大排k=1;/初始kfor(int col=0;col4;col+)for(int row=0;row4;row+)arrrowcol=k;k+;System.out.println();for(int row=0;row4;row+)for(int col=0;col4;col+)System.out.print(arrrowcol+t);System.out.println();21. 上三角和下三角练习public class Test2 public static void main(String args) / 带0输出的数组int arr=new int44;int k=1;for(int row=0;row4;row+)for(int col=0;col4;col+)if(row=col)/row=col 上三角arrrowcol=k+;elsearrrowcol=0;System.out.print(arrrowcol+t);System.out.println();/不带0输出的上三角/*int arr=new int44;int k=1;for(int row=0;row4;row+)for(int col=0;colrow+1;col+)arrrowcol=k;System.out.print(arrrowcol+t);k+;System.out.println();*/22. 偶数列小到大输出，奇数列大到小输出public class Test2 public static void main(String args) / TODO Auto-generated method stubint arr = new int55;int k = 1;for (int col = 0; col 5; col+) if (col % 2 = 0) for (int row = 0; row = 0; row-) arrrowcol = k+;for (int row = 0; row 5; row+) for (int col = 0; col 5; col+) System.out.print(arrrowcol+t);System.out.println();23. 数组方式随机抽取4张牌public class Test2 public static void main(String args) int deck=new int52;Stringsuits=黑桃,红桃,方块,梅花;Stringranks=A,2,3,4,5,6,7,8,9,10,J,Q,K;/初始化每一张牌for(int i=0;ideck.length;i+)decki=i;/打乱牌的次序for(int i=0;ideck.length;i+)/随机产生一个元素下标051int index=(int)(Math.random()*deck.length);int temp=decki;decki=deckindex;deckindex=temp;/显示输出前4张牌for(int i=0;i4;i+)String suit= suitsdecki/13;String rank=ranksdecki%13;System.out.println(suit+ +rank);24. 二维数组输出类似杨辉三角public class Test2 public static void main(String args) int arr = new int1010;for(int i=0;i10;i+)for(int j=0;j=i;j+)if(j=0|j=i)arrij=1;/开头和末尾为1elsearrij=arri-1j-1+arri-1j;/中间数值规律for(int i=0;i10;i+)for(int j=0;j10;j+)System.out.print(arrij+t);System.out.println();25. 两个矩阵相乘import java.util.*;public class Test public static void main(String args) Random rand = new Random();/ 生成2个矩阵并随机赋值Scanner sc = new Scanner(System.in);int arr1 = new int25;int arr2 = new int53;for (int r = 0; r 2; r+) for (int c = 0; c 5; c+) arr1rc = rand.nextInt(5);System.out.print(arr1rc + );System.out.println();System.out.println();for (int r = 0; r 5; r+) for (int c = 0; c 3; c+) arr2rc = rand.nextInt(5);System.out.print(arr2rc + );System.out.println();System.out.println();/ 相乘规则int arr3 = new int23;/ 创建一个0矩阵等待赋值for (int r = 0; r 2; r+) for (int c = 0; c 3; c+) int sum = 0;for (int u = 0; u 5; u+) sum = sum + arr1ru * arr2uc;/ 矩阵第r行，第c列每个元素相乘再相加/ 将sum赋值于arr3的r行c列位置arr3rc = sum;System.out.println(结果如下：);for (int i = 0; i 2; i+) for (int j = 0; j 3; j+) System.out.print(arr3ij + t);System.out.println();26. 函数调用练习import java.util.Random;public class Test int arr=new int55;public void Intt()Random rand=new Random();for(int r=0;r5;r+)for(int c=0;c5;c+)arrrc=rand.nextInt(20);System.out.print(arrrc+t);System.out.println();public static void main(String args) Test t=new Test();t.Intt();27. 鞍点（1）import java.util.Random;public class Test int arr=new int55;public void Intt()Random rand=new Random();for(int r=0;r5;r+)for(int c=0;c5;c+)arrrc=rand.nextInt(20);System.out.print(arrrc+t);System.out.println();public void AnDian()for(int r=0;r5;r+)int maxC=0;for(int j=1;j5;j+)if(arrrmaxCarrrj)maxC=j;boolean Flag=true;for(int u=0;u5;u+)if(arrumaxCarrrmaxC)Flag=false;if(Flag=true)System.out.print(+r+,+maxC+)是鞍点，其值为+arrrmaxC);public static void main(String args) Test t=new Test();t.Intt();t.AnDian();28. 鞍点（2）import java.util.Random;public class AnDian int n=3;int arr=new intnn;/数组初始化public void Intt()Random rand=new Random();for(int r=0;rn;r+)for(int c=0;cn;c+)arrrc=rand.nextInt(50)+10;System.out.print(arrrc+t);System.out.println();/从列找出最小，再从行找最大public void AD()for(int c=0;cn;c+)int minR=0;for(int r=0;rarrrc)minR=r;boolean