标签：Java int System 学习 ++ 数组 arrays println out

Java数组学习

ArrayDemo1

package com.yuan.array;

public class ArrayDemo1 {
    //变量的类型     变量的名字   =   变量的值;
    //数组类型
    //数组的长度是确定的，一旦被创建，大小就是不可以被改变的。
    public static void main(String[] args) {
        int[] nums;//1.声明了一个数组       int nums[];第二种定义方式（C和C++程序员常用）
        nums = new int[10];//2.创建了一个数组，这里面可以存放10个int类型的数字
        int[] nums2 = new int[10];//可以将两步综合成一步
        //3.给数组元素中赋值(int类型默认值是0，String默认值是NULL)
        nums[0] = 1;
        nums[1] = 2;
        nums[2] = 3;
        nums[3] = 4;
        nums[4] = 5;
        nums[5] = 6;
        nums[6] = 7;
        nums[7] = 8;
        nums[8] = 9;
        nums[9] = 10;

        //计算所有元素的和
        int sum=0;
        //获取数组长度：array.length
        for (int i = 0; i < nums.length; i++) {
            sum = sum +nums[i];
        }
        System.out.println("总和为"+sum);

    }
}

ArrayDemo2

package com.yuan.array;

public class ArrayDemo2 {
    public static void main(String[] args) {
        //静态初始化
        int[] a ={1,2,3,4,5,6,7,8};

        System.out.println(a[0]);
        //引用类型
        Man[] mans = {new Man(),new Man()};//Man是一个外面的类，没有写内容

        //动态初始化：包含默认初始化
        int [] b= new int[10];
        b[0]=10;
        System.out.println(b[0]);

    }
}

ArrayDemo3

package com.yuan.array;

public class ArrayDemo3 {
    public static void main(String[] args) {
        int[] arrays = {1,2,3,4,5};

        //打印全部的数据元素
        for (int i = 0; i < arrays.length; i++) {
            System.out.println(arrays[i]);
        }
        System.out.println("=========");
        //计算所有元素的总和
        int sum =0;
        for (int i = 0; i < arrays.length; i++) {
            sum = sum +arrays[i];
        }
        System.out.println("sum="+sum);
        System.out.println("=========");
        //查找最大元素
        int max = arrays[0];
        for (int i = 1; i < arrays.length; i++) {
            if(arrays[i]>max){
                max = arrays[i];
            }
        }
        System.out.println("max="+max);

    }
}

ArrayDemo4

package com.yuan.array;

public class ArrayDemo4 {
    public static void main(String[] args) {
        int[] arrays = {1,2,3,4,5};

//        //JDK1.5，没有下标,取不到下标
//        //for(数组里面的每一个值:数组)
//        for (int array1 : arrays) {
//            System.out.println(array1);
//        }


//        printArray(arrays);
        int[] reverse = reverse(arrays);
        printArray(reverse);


    }
    //打印数组元素
    //static是为了方便直接调用
    public static void printArray(int[] arrays){
        for (int i = 0; i < arrays.length; i++) {
            System.out.print(arrays[i]+" ");
        }
    }

    //反转数据
//    public static int[] reverse(int[] arrays){
//        int[] result = new int[arrays.length];
//
//        //反转的操作
//        for (int i = 0; i < arrays.length; i++) {
//            result[i] = arrays[arrays.length-i-1];
//        }
//
//
//        return result;
//    }

    public static int[] reverse(int[] arrays){
        int[] result = new int[arrays.length];

        //反转的操作
        for (int i = 0,j=result.length-1; i < arrays.length; i++,j--) {
            result[j] = arrays[i];
        }


        return result;
    }


}

/*
1.普通的for循环（最常用）
2.For-Each循环（用于打印一些结果）
3.数组作方法入参（可以对数组进行一些操作）
4.数组作返回值（返回新的数组）
 */

ArrayDemo5

package com.yuan.array;

import javax.xml.transform.Source;

public class ArrayDemo5 {
    public static void main(String[] args) {
        int[][] array = {{1,2},{2,3},{3,4},{4,5}};





        for (int i = 0; i < array.length; i++) {
            for (int j = 0; j < array[i].length; j++) {
                System.out.print(array[i][j]+" ");
            }

            System.out.println();
            
        }



    }

    public static void printArray(int[] arrays){
        for (int i = 0; i < arrays.length; i++) {
            System.out.print(arrays[i]+" ");
        }
    }


}

ArrayDemo6

package com.yuan.array;

import java.util.Arrays;

public class ArrayDemo6 {
    public static void main(String[] args) {
        int[] a ={1,2,3,4,5,1561,6115,12,31215,6};

        //System.out.println(a);//[I@1b6d3586

        //打印数组元素Arrays.toString
        System.out.println(Arrays.toString(a));
        printArray(a);
        System.out.println();
        Arrays.sort(a);//数组进行排序
        System.out.println(Arrays.toString(a));

        Arrays.fill(a,0);
        System.out.println(Arrays.toString(a));

    }

    public static void printArray(int[] a){
        for (int i = 0; i < a.length; i++) {
            if (i==0){
                System.out.print("[");
            }
            if (i==a.length-1){
                System.out.print(a[i]+"]");
            }else {
                System.out.print(a[i]+", ");
            }

        }
    }

}

ArrayDemo7

package com.yuan.array;

import java.util.Arrays;

public class ArrayDemo7 {
    public static void main(String[] args) {

        int[] a ={1,4,56,24,95,123,45,84,64};
        int[] sort = sort(a);

        System.out.println(Arrays.toString(a));
        System.out.println(Arrays.toString(sort));

    }

    //  冒泡排序
    //1.比较数组中两个相邻的元素，如果第一个数比第二个数大，我们就交换位置
    //2.每一次比较，都会产生出最大或者最小的元素
    //3.下一轮可以少排一次序
    //4.依次循环直到结束

    public static int[] sort(int[] array){
        //临时变量
        int temp = 0;
        //外层循环判断走多少次
        for (int i = 0; i < array.length-1; i++) {

            boolean flag;//通过flag标识位较少没有意义的比较

            //内层循环比较两个数
            for (int j = 0; j < array.length-1-i; j++) {
                if(array[j+1]<array[j]){
                    temp = array[j];
                    array[j] = array[j+1];
                    array[j+1] = temp;
                }
            }

            if(flag = false){
                break;
            }

        }

        return array;

    }

}

ArrayDemo8

package com.yuan.array;

public class ArrayDemo8 {
    public static void main(String[] args) {
        //1.创建一个二维数组 11*11  0没有棋子 1黑棋 2白棋
        int[][] array1 = new int[11][11];
        array1[1][2] = 1;
        array1[2][3] = 2;
        //输出原始的数组
        System.out.println("输出原始的数组");

        for (int[] ints : array1) {
            for (int anInt : ints) {
                System.out.print(anInt+"\t");
            }
            System.out.println();
        }

        System.out.println("=============");


        //转换为稀疏数组保存
        //获取有效值的个数
        int sum = 0;
        for (int i = 0; i < 11; i++) {
            for (int j = 0; j < 11; j++) {
                if(array1[i][j]!=0){
                    sum++;
                }
            }
        }
        System.out.println("有效值的个数"+sum);

        //2.创建一个稀疏数组的数组
        int[][] array2 = new int[sum+1][3];
        array2[0][0]=11;
        array2[0][1]=11;
        array2[0][2]=sum;

        //遍历二维数组，将非零的值，放在稀疏数组中
        int count = 0;
        for (int i = 0; i < array1.length; i++) {
            for (int j = 0; j < array1[i].length; j++) {
                if (array1[i][j]!=0){
                    count++;
                    array2[count][0] = i;
                    array2[count][1] = j;
                    array2[count][2] = array1[i][j];
                }
            }
        }

        //输出稀疏数组
        System.out.println("稀疏数组");

        for (int i = 0; i < array2.length; i++) {
            System.out.println(array2[i][0]+"\t"
                                +array2[i][0]+"\t"
                                +array2[i][2]+"\t");
        }


        System.out.println("=============");
        System.out.println("还原");
        //1.读取稀疏数组
        int[][] array3 = new int [array2[0][0]][array2[0][1]];

        for (int i = 1; i < array2.length; i++) {
            array3[array2[i][0]][array2[i][1]] = array2[i][2];
        }

        //3.打印
        System.out.println("输出还原的数组");

        for (int[] ints : array3) {
            for (int anInt : ints) {
                System.out.print(anInt+"\t");
            }
            System.out.println();
        }


    }
}

FiveInARow

package com.yuan;
import java.util.Scanner;
import java.io.*;

public class FiveInARow {
    private static final int BOARD_SIZE = 15;
    private static char[][] board = new char[BOARD_SIZE][BOARD_SIZE];
    private static char currentPlayer = 'X';

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int choice = 0;

        System.out.println("欢迎来到五子棋游戏！");

        while (true) {
            System.out.println("请选择：");
            System.out.println("1. 开始新游戏");
            System.out.println("2. 续上一盘");
            System.out.println("3. 退出游戏");

            choice = scanner.nextInt();

            if (choice == 1) {
                newGame();
                play(scanner);
            } else if (choice == 2) {
                if (!loadGame()) {
                    System.out.println("续上一盘失败。");
                    continue;
                }
                play(scanner);
            } else if (choice == 3) {
                System.out.println("再见！");
                break;
            } else {
                System.out.println("输入无效，请重新输入。");
            }
        }
    }

    private static void newGame() {
        for (int i = 0; i < BOARD_SIZE; i++) {
            for (int j = 0; j < BOARD_SIZE; j++) {
                board[i][j] = '-';
            }
        }
        currentPlayer = 'X';
    }

    private static void play(Scanner scanner) {
        int row, col;

        while (true) {
            printBoard();

            System.out.println("请 " + currentPlayer + " 玩家输入坐标（行列，以空格分隔）：");
            row = scanner.nextInt();
            col = scanner.nextInt();

            if (row < 0 || row >= BOARD_SIZE || col < 0 || col >= BOARD_SIZE) {
                System.out.println("输入无效，请重新输入。");
                continue;
            }

            if (board[row][col] != '-') {
                System.out.println("该位置已经有棋子了，请重新输入。");
                continue;
            }

            board[row][col] = currentPlayer;

            if (checkWin(row, col)) {
                System.out.println("恭喜 " + currentPlayer + " 玩家获胜！");
                printBoard();
                break;
            }

            if (checkTie()) {
                System.out.println("平局！");
                printBoard();
                break;
            }

            currentPlayer = currentPlayer == 'X' ? 'O' : 'X';
        }
    }

    private static boolean checkWin(int row, int col) {
        char c = board[row][col];
        int count = 1;

        // 水平方向
        for (int i = col - 1; i >= 0 && board[row][i] == c; i--) {
            count++;
        }
        for (int i = col + 1; i < BOARD_SIZE && board[row][i] == c; i++) {
            count++;
        }
        if (count >= 5) {
            return true;
        }

        // 垂直方向
        count = 1;
        for (int i = row - 1; i >= 0 && board[i][col] == c; i--) {
            count++;
        }
        for (int i = row + 1; i < BOARD_SIZE && board[i][col] == c; i++) {
            count++;
        }
        if (count >= 5) {
            return true;
        }
        // 左上到右下方向
        count = 1;
        for (int i = row - 1, j = col - 1; i >= 0 && j >= 0 && board[i][j] == c; i--, j--) {
            count++;
        }
        for (int i = row + 1, j = col + 1; i < BOARD_SIZE && j < BOARD_SIZE && board[i][j] == c; i++, j++) {
            count++;
        }
        if (count >= 5) {
            return true;
        }

        // 右上到左下方向
        count = 1;
        for (int i = row - 1, j = col + 1; i >= 0 && j < BOARD_SIZE && board[i][j] == c; i--, j++) {
            count++;
        }
        for (int i = row + 1, j = col - 1; i < BOARD_SIZE && j >= 0 && board[i][j] == c; i++, j--) {
            count++;
        }
        if (count >= 5) {
            return true;
        }

        return false;
    }

    private static boolean checkTie() {
        for (int i = 0; i < BOARD_SIZE; i++) {
            for (int j = 0; j < BOARD_SIZE; j++) {
                if (board[i][j] == '-') {
                    return false;
                }
            }
        }
        return true;
    }

    private static void printBoard() {
        System.out.print("  ");
        for (int i = 0; i < BOARD_SIZE; i++) {
            System.out.print(i + " ");
        }
        System.out.println();

        for (int i = 0; i < BOARD_SIZE; i++) {
            System.out.print(i + " ");
            for (int j = 0; j < BOARD_SIZE; j++) {
                System.out.print(board[i][j] + " ");
            }
            System.out.println();
        }
    }

    private static boolean saveGame() {
        try {
            BufferedWriter writer = new BufferedWriter(new FileWriter("save.txt"));

            for (int i = 0; i < BOARD_SIZE; i++) {
                for (int j = 0; j < BOARD_SIZE; j++) {
                    writer.write(board[i][j]);
                }
                writer.newLine();
            }

            writer.write(currentPlayer);
            writer.newLine();

            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        }

        return true;
    }

    private static boolean loadGame() {
        try {
            BufferedReader reader = new BufferedReader(new FileReader("save.txt"));

            for (int i = 0; i < BOARD_SIZE; i++) {
                String line = reader.readLine();
                if (line == null || line.length() != BOARD_SIZE) {
                    return false;
                }
                for (int j = 0; j < BOARD_SIZE; j++) {
                    board[i][j] = line.charAt(j);
                }
            }

            String line = reader.readLine();
            if (line == null || line.length() != 1) {
                return false;
            }
            currentPlayer = line.charAt(0);

            reader.close();
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        }

        return true;
    }
}

标签：Java,int,System,学习,++,数组,arrays,println,out
From： https://www.cnblogs.com/codehuman/p/17150562.html