Day10 综合任务1

1、 continue 是进入下一次循环，而 break 是跳出整个循环体；

2、 tempRandom.nextInt(n) 就可以生成0-n之间的随机数，

3、用循环每次求学生的总成绩，如果有不及格的成绩就不再参与评比，每次成绩对比后留下最高成绩和这个学生的编号，

import java.util.Arrays;
import java.util.Random;

public class Task1 {
    public static void main(String args[]) {
        task1();
    }// Of main

    public static void task1() {
        // Step 1. Generate the data whie n students and m sourses.
        // Set these values bug yourself.
        int n = 10;
        int m = 3;
        int lowerBound = 50;
        int upperBound = 90;
        int threshold = 60;

        // Here we have to use an object to generate random numbers.
        Random tempRandom = new Random();
        int[][] data = new int[n][m];
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                data[i][j] = lowerBound + tempRandom.nextInt(upperBound - lowerBound);
            } // Of for j
        } // Of for i

        System.out.println("The data is:\r\n" + Arrays.deepToString(data));

        // Step 2. Compute the total score of each student.
        int[] totalScores = new int[n];
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                if (data[i][j] < threshold) {
                    totalScores[i] = 0;
                    break;
                } // Of if

                totalScores[i] += data[i][j];
            } // Of for j
        } // Of for i
        System.out.println("The total scores are:\r\n" + Arrays.toString(totalScores));

        // Step 3. Find the best and worst student.
        // Typical initialization for index: invalid value.
        int tempBestIndex = -1;
        int tempWorstIndex = -1;
        // Typical initialization for best and worst values.
        int tempBestScore = 0;
        int tempWorstScore = m * upperBound + 1;
        for (int i = 0; i < n; i++) {
            // Do not consider failed students.
            if (totalScores[i] == 0) {
                continue;
            } // Of if

            if (tempBestScore < totalScores[i]) {
                tempBestScore = totalScores[i];
                tempBestIndex = i;
            } // Of if

            if (tempWorstScore > totalScores[i]) {
                tempWorstScore = totalScores[i];
                tempWorstIndex = i;
            } // Of if
        } // Of for i

        // using "else if",because a student can be both wht best and the worst
        // Step 4. Output the student number and score.
        if (tempBestIndex == -1) {
            System.out.println("Cannot find the best student. All sudent have failed.");
        } else {
            System.out.println("The best student is No." + tempBestIndex + " with scores: "
                    + Arrays.toString(data[tempBestIndex]));
        } // Of if

        if (tempWorstIndex == -1) {
            System.out.println("Cannot find the best student. All sudent have failed.");
        } else {
            System.out.println("The worst student is No." + tempWorstIndex + " with scores: "
                    + Arrays.toString(data[tempWorstIndex]));
        } // Of if

    }// Of task1
}

 4、关于 Arrays.toString() 和 Arrays.deepToString() ， deepToString 是输出多维数组的， toString 是输出一维的，这里的一维是相对的。比如这里 tem 虽然是二阶数组，但是 tem[1] 就是指 {3, 4} ，也是一维的。 tem.toString() 就是输出地址。

 

import java.util.Arrays;
public class toString {
    public static void main(String args[]) {
        int[][] tem = new int[][]{
            {1,2},
            {3,4},
            {5,6}
        };
        System.out.println(Arrays.deepToString(tem));
        System.out.println(Arrays.toString(tem[1]));
        System.out.println(tem.toString());
        System.out.println(tem[1].toString());

    }
    
}