• 数组博客


    一.   动手动脑1

      1. 代码

    public class PassArray {

        

         public static void main(String[] args) {

                int a[] = { 1, 2, 3, 4, 5 };

                String output = "The values of the original array are: ";

     

                for (int i = 0; i < a.length; i++)

                       output += "   " + a[i];

     

                output += " Effects of passing array " + "element call-by-value: "

                              + "a[3] before modifyElement: " + a[3];

     

                modifyElement(a[3]);//按值传递,值不变。

     

                output += " a[3] after modifyElement: " + a[3];

     

                output += " Effects of passing entire array by reference";

     

                modifyArray(a); // array a passed call-by-reference按引用传递,值都变了

     

                output += " The values of the modified array are: ";

     

                for (int i = 0; i < a.length; i++)

                       output += "   " + a[i];

               

                System.out.println(output);

         }

     

         public static void modifyArray(int b[]) {

                for (int j = 0; j < b.length; j++)

                       b[j] *= 2;

         }

     

         public static void modifyElement(int e) {

                e *= 2;

         }

     

    }

      2.实验结果:

        

      3.实验分析:分别是引用传递和值传递。使用引用传递时,如果方法中有代码更改了数组元素的值,实际上是直接修改了原始数组元素。后者按值传递,方法体中只是原始数据元素的一个拷贝,所以不会更改。

     二.课堂练习1

       1.实验代码:

                publicclass ArrayInRam {

         publicstaticvoid main(String[] args) {

                // 定义并初始化数组,使用静态初始化

                int[] a = { 5, 7, 20 };

                System.out.println("a数组中的元素:");

                // 循环输出a数组的元素

                for (int i = 0; i < a.length; i++) {

                       System.out.print(a[i] + ",");

                }

                // 定义并初始化数组b,使用动态初始化

                int[] b = newint[4];

                // 输出b数组的长度

                System.out.println(" b数组的初始长度为:" + b.length);

                // 因为aint[]类型,b也是int[]类型,所以可以将a的值赋给b

                // b的长度改变的原因是:b引用指向a引用指向的数组

                b = a;

                System.out.println("b=a,赋值之后,b数组的元素为:");

                // 循环输出b数组的元素

               

                for (int i = 0; i < b.length; i++) {

                       System.out.print(b[i] + ",");

                }

     

                // 再次输出b数组的长度

                System.out.println(" 赋值之后,b数组的长度为:" + b.length);

         }

    }

    2.实验结果:

        

    3.原因分析:b数组起初定义的长度为4,而将数组a赋值给数组b是让b引用指向a引用指向的数组,所以后面长度会变。

    三.动手动脑2

       1.代码:

          

    import java.io.*;

     

    publicclass QiPan

    {

         //定义一个二维数组来充当棋盘

         private String[][] board;

         //定义棋盘的大小

         privatestaticintBOARD_SIZE = 15;

         publicvoid initBoard()

         {

                //初始化棋盘数组

                board = new String[BOARD_SIZE][BOARD_SIZE];

                //把每个元素赋为"",用于在控制台画出棋盘

                for (int i = 0 ; i < BOARD_SIZE ; i++)

                {

                       for ( int j = 0 ; j < BOARD_SIZE ; j++)

                       {

                              board[i][j] = "";

                       }

                }

         }

         //在控制台输出棋盘的方法

         publicvoid printBoard()

         {

                //打印每个数组元素

                for (int i = 0 ; i < BOARD_SIZE ; i++)

                {

                       for ( int j = 0 ; j < BOARD_SIZE ; j++)

                       {

                              //打印数组元素后不换行

                              System.out.print(board[i][j]);

                       }

                       //每打印完一行数组元素后输出一个换行符

                       System.out.print(" ");

                }

         }

        publicstaticvoid main(String[] args)throws Exception

        {

            QiPan gb = new QiPan();

                gb.initBoard();

                gb.printBoard();

                //这是用于获取键盘输入的方法

                BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

                String inputStr = null;

                    System.out.println("请输入您下棋的座标,应以x,y的格式:");

                //br.readLine():每当在键盘上输入一行内容按回车,刚输入的内容将被br读取到。

                while ((inputStr = br.readLine()) != null)

                {

                       //将用户输入的字符串以逗号(,)作为分隔符,分隔成2个字符串

                       String[] posStrArr = inputStr.split(",");

                       //2个字符串转换成用户下棋的座标

                       int xPos = Integer.parseInt(posStrArr[0]);

                       int yPos = Integer.parseInt(posStrArr[1]);

                       //把对应的数组元素赋为"●"

                       gb.board[xPos - 1][yPos - 1] = "●";                           

                       /*

                        电脑随机生成2个整数,作为电脑下棋的座标,赋给board数组。

                        还涉及

                              1.座标的有效性,只能是数字,不能超出棋盘范围

                              2.如果下的棋的点,不能重复下棋。

                              3.每次下棋后,需要扫描谁赢了

                        */

                       gb.printBoard();

                       System.out.println("请输入您下棋的座标,应以x,y的格式:");

                }

        }

    }

     

        2.实验结果截图:

        

    3.程序分析:首先定义一个二维数组,长度均为15,然后建立一个棋盘方法,利用循环语句,每行15+号,一共1515+号,为棋盘的最初是状态,然后再建立一个输出方法,用一个循环把每一行的都棋盘输出,每行输出15个之后进行换行,然后在让用户输入坐标形式的下棋位置,再以逗号为分隔符,分成两部分x,y,然后将用户所选的下棋图标●将gb.board[x-1][y-1]位置的+号替换,输出结果即可。

    四.动手动脑31):

       1.代码:

                       publicclass Num2Rmb

    {

         private String[] hanArr = {"" , "" , "" , "" , "" ,

                "" , "" , "" , "" , ""};

         private String[] unitArr = {"" , "" , "","","十万","百万"};

         /**

          * 把一个四位的数字字符串变成汉字字符串

          * @param numStr 需要被转换的四位的数字字符串

          * @return四位的数字字符串被转换成的汉字字符串。

          */

         String toHanStr(String numStr)

         {

                String result = "";

                int numLen = numStr.length();

        

                for (int i = 0 ; i < numLen ; i++ )      

                {

     

                       int num = numStr.charAt(i) - 48;

                       if ( i != numLen - 1 && num != 0)

                       {

                              result += hanArr[num] + unitArr[numLen - 2 - i];

                       }

        

                       else

                       {

        

                              if(result.length()>0 && hanArr[num].equals("") && result.charAt(result.length()-1)=='')

                                     continue;

                              result += hanArr[num];

                       }

                }

     

                if(result.length()==1)

                       return result;

               

                int index=result.length()-1;

                while(result.charAt(index)==''){

                       index--;

                }

                if(index!=result.length()-1)

                       return result.substring(0,index+1);

                else {

                       return result;

                }

         }

     

        publicstaticvoid main(String[] args)

        {       

                Num2Rmb nr = new Num2Rmb();

                System.out.println("只支持整数(0~百万)");

     

                System.out.println(nr.toHanStr("0"));

                System.out.println(nr.toHanStr("1"));

                System.out.println(nr.toHanStr("10"));

                System.out.println(nr.toHanStr("15"));

                System.out.println(nr.toHanStr("110"));

                System.out.println(nr.toHanStr("123"));

                System.out.println(nr.toHanStr("105"));

                System.out.println(nr.toHanStr("1000"));

                System.out.println(nr.toHanStr("1100"));

                System.out.println(nr.toHanStr("1110"));

                System.out.println(nr.toHanStr("1005"));

                System.out.println(nr.toHanStr("1105"));

                System.out.println(nr.toHanStr("1111"));

                System.out.println(nr.toHanStr("10000"));

                System.out.println(nr.toHanStr("10001"));

                System.out.println(nr.toHanStr("10011"));

                System.out.println(nr.toHanStr("10111"));

                System.out.println(nr.toHanStr("11111"));

                System.out.println(nr.toHanStr("11000"));

                System.out.println(nr.toHanStr("11100"));

                System.out.println(nr.toHanStr("11110"));

                System.out.println(nr.toHanStr("101110"));

                System.out.println(nr.toHanStr("1001110"));

               

        }

    }

     

        2.实验结果:

      

    五.动手动脑32):

        1.代码:

         publicclass complicate {

     

         /**

          * @param args

          */

         private String [] han={ "","" , "" , "" , "" ,

                       "" , "" , "" , "" , ""};

         private String [] unit={"","","","","","","","拾萬","佰萬"};//121.21

        

         String toHan(String numstr)

         {

                String result="";

                int len=numstr.length();

                int position=0;

                position=numstr.indexOf('.');

                if(position>0)

                {

                for(int i=0;i<len;i++)

                {

                       int num=numstr.charAt(i)-48;

               

               

                       if((num!=0&&i<position))

                       {

                              result+=han[num]+unit[len-2-i];

                       }

                       elseif(num!=0&&i>position)

                       {

                              result+=han[num]+unit[len-1-i];

                       }

                       elseif(num==0&&i<len-1)

                       {

                              result+=han[num];

                       }

               

                }

                }

     

             return  result;

               

         }

         publicstaticvoid main(String[] args) {

                // TODO Auto-generated method stub

                complicate com=new complicate();

                System.out.println("请输入千万以内的钱,精确到分:");

                System.out.println(com.toHan("123.52"));

               

         }

     

    }

     

        2.实验截图:

            

    六.动手动脑4

       1.代码:

                import java.io.BufferedReader;

    import java.io.IOException;

    import java.io.InputStreamReader;

    publicclass BigInteger {

     

         publicstaticvoid main(String[] args) throws IOException {

                // TODO Auto-generated method stub

                BigNumber input;

                System.out.println("输入一个正整数:");

                input = inputInteger();

                System.out.println("输入另一个正整数:");

                int a[] = inputArray();

                System.out.println("两个数的和是:");

                display(input.add(a));

               

         }

         publicstaticint[] inputArray()throws IOException{

                InputStreamReader reader = new InputStreamReader(System.in);

                BufferedReader input = new BufferedReader(reader);

                String number = input.readLine();

               

                char temp[] = number.toCharArray();

                int array[] = newint[temp.length];

                for(int i=0; i<temp.length; i++){

                       if(temp[i] < '0' || temp[i] > '9'){

                              System.out.println("输入错误!");

                              System.exit(1);

                       }

                       array[i] = temp[i]-'0';

                }

                return array;

         }

         publicstatic BigNumber inputInteger()throws IOException{

                InputStreamReader reader = new InputStreamReader(System.in);

                BufferedReader input = new BufferedReader(reader);

                String number = input.readLine();

               

                char temp[] = number.toCharArray();

                int array[] = newint[temp.length];

                for(int i=0; i<temp.length; i++){

                       if(temp[i] < '0' || temp[i] > '9'){

                              System.out.println("输入错误!");

                              System.exit(1);

                       }

                       array[i] = temp[i]-'0';

                }

                BigNumber a = new BigNumber(array);

                return a;

         }

         publicstaticvoid display(int[] a){

                for(int i = 0; i < a.length; i++)

                       System.out.print(a[i]);

                System.out.println();

         }

         public BigInteger(){}

         public BigInteger(int[] array){

                for(int i=0;i < array.length && i < this.array.length;i++){

                       this.array[i] = array[i];

                       len++;

                }

         }

         publicvoid display(){

                for(int i = 0; i < len;i++){

                       System.out.print(array[i]);

                }

         }

         publicvoid setIneger(int[] array){

                len=0;

                for(int i=0; i < this.array.length && i < array.length; i++){

                       this.array[i] = array[i];

                       len++;

                }

               

         }

         publicint[] getInteger(){returnthis.array;}

         publicint getLength(){returnthis.len;}

         publicint[] add(int[] addend){

                int firstlen = len;//第一个加数的长度。

                int secondlen = (int) addend.length;//第二个加数的长度。

                int gap = Math.abs(firstlen-secondlen);//两个数长度差。

                int thirdlen = firstlen > secondlen? firstlen:secondlen;

                int result[] = newint[thirdlen+1];         //相加过程

                int temp=0; //进位数。

                for(int i = thirdlen-1; i >=gap;i--){

                       if(firstlen < secondlen){

                              result[i+1] = (array[i-gap]+addend[i])%10 +temp;

                              temp = (array[i-gap]+addend[i])/10;

                       }else{

                              result[i+1] = (array[i]+addend[i-gap])%10 +temp;

                              temp = (array[i]+addend[i-gap])/10;

                       }

                }

                int j = 1;

                do{

                       if(firstlen < secondlen){

                              result[j] = addend[j-1];

                       }elseif(firstlen > secondlen){

                              result[j] = array[j-1];

                       }j++;

                }while(j < gap);

                if(temp != 0){

                       result[0] = temp;

                }else{

                       int s[] = newint[thirdlen];

                       for(int i=0; i < thirdlen; i++)

                              s[i] = result[i+1];

                       return s;

                }

                return result;

         }

        

         privateintarray[] = newint[20];

         privateintlen = 0;

    }

    2.实验截图:

      

    3.实验分析:利用数字实现大数的表示,通过将大数的各个位上的数字分开,进行相加计算,相加满10进位。

    七.生成随机数:

       1.设计思想:首先,定义一个长度为10的数字,然后通过for循环随机产生了10个数,赋值给output,然后再通过一个for循环把数组a里面的10个数字进行相加,最后在屏幕通过消息框输出。

     

     

       2.程序流程图

        

          

            

        3.程序源代码:

               import javax.swing.JOptionPane;

    public class Random {

     

          /**

           * @param args

           */

          public static void main(String[] args) {

                 // TODO Auto-generated method stub

                 int a[]=new int[10];

                 int sum=0;

                 String output=new String();

                 for(int i=0;i<a.length;i++)

                 {

     

                    a[i]=(int)(Math.random()*100);

     

                 }

     

                 output+="a[10]=";

     

                 for(int i=0;i<a.length;i++)

     

                 {

     

                     output+=a[i]+" ";

     

                 }

     

                 for(int i=0;i<a.length;i++)

     

                 {

     

                        sum+=a[i];

     

                 }

     

                 output+=" sum:"+sum;

     

                  

     

                 JOptionPane.showMessageDialog(null, output,"结果",

     

                 JOptionPane.PLAIN_MESSAGE);

     

                 }

     

    }

     

       4.结果截图:

      

    5.编程总结:注意开始定义数组和字符串的初始化,运用训话语句,随机生成10个数给数字a。

     


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  • 原文地址:https://www.cnblogs.com/xieshiyu/p/6036521.html
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