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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7.  
  8.  class GradeBookTest 
  9.  { 
  10. 	public static void main( String[] args ) 
  11. 	{ 
  12.  
  13. 		int[] gradesArray = { 87, 68, 94, 100, 83, 78, 85, 91, 76, 87 }; 
  14.  
  15. 		GradeBook myGradeBook = new GradeBook("CS101 Introduction to Java Programming", gradesArray ); 
  16. 		myGradeBook.displayMessage(); 
  17. 		myGradeBook.processGrades(); 
  18. 	} 
  19.  } 
  20.  
  21.  
  22.  class GradeBook 
  23.  { 
  24. 	private String courseName; 
  25. 	private int[] grades; 
  26.  
  27. 	public GradeBook( String name, int[] gradesArray ) 
  28. 	{ 
  29. 		courseName = name;
  30. 		grades = gradesArray; 
  31. 	} 
  32. 	public void setCourseName( String name ) 
  33. 	{ 
  34. 		courseName = name;
  35. 	} 
  36. 	public String getCourseName() 
  37. 	{ 
  38. 		return courseName;
  39. 	} 
  40. 	public void displayMessage() 
  41. 	{ 
  42. 		System.out.printf( "Welcome to the grade book for %s!\n",getCourseName() ); 
  43. 	} 
  44. 	public void processGrades() 
  45. 	{ 
  46. 		outputGrades(); 
  47. 		System.out.printf( "Class average is %.2f\n", getAverage() ); 
  48. 		System.out.printf( "Class average is %.2f(遞迴)", getAverage(grades.length) ); 
  49. 		outputBarChart(); 
  50. 	} 
  51.  
  52. 	public double getAverage() 
  53. 	{ 
  54. 		int total = 0; // initialize total
  55. 		for ( int grade : grades ) 
  56. 			total += grade; 
  57. 		return ( double ) total / grades.length; 
  58. 	} 
  59.  
  60. 	public double getAverage(int n)
  61. 	{
  62. 		if(n == 0)
  63. 			return grades[0];
  64. 		return (grades[n-1]+getAverage(n-1)*(n-1) ) / n;
  65. 	}
  66. 	public void outputBarChart() 
  67. 	{
  68. 		int[] frequency=new int[11];
  69.  
  70. 		for(int i = 0; i < grades.length; i++){
  71. 			frequency[grades[i]/10]++;  //例如25分 歸類到frequency[2]
  72. 		}
  73.  
  74. 		System.out.println();
  75. 		System.out.print("Grade distribution:");
  76. 		for(int i = 0; i < frequency.length; i++){
  77. 			System.out.println();
  78. 			if(i == frequency.length-1)
  79. 				System.out.print("100:");
  80. 			else
  81. 				System.out.print(i+"0-"+i+"9:");
  82. 			for(int j = 0; j < frequency[i]; j++){
  83. 				System.out.print("*");
  84. 			}
  85. 		}
  86.  
  87. 	}	
  88.  
  89. 	public void outputGrades() 
  90. 	{ 
  91. 		System.out.println( "The grades are:" ); 
  92. 		for ( int student = 0; student < grades.length; student++ ) 
  93. 			System.out.printf( "Student %2d: %3d\n", student + 1, grades[ student ] ); 
  94. 	} 
  95.  }
Success #stdin #stdout 0.05s 2184192KB
comments (?)
stdin 
Standard input is empty
stdout 
Welcome to the grade book for CS101 Introduction to Java Programming!
The grades are:
Student  1:  87
Student  2:  68
Student  3:  94
Student  4: 100
Student  5:  83
Student  6:  78
Student  7:  85
Student  8:  91
Student  9:  76
Student 10:  87
Class average is 84.90
Class average is 84.90(遞迴)
Grade distribution:
00-09:
10-19:
20-29:
30-39:
40-49:
50-59:
60-69:*
70-79:**
80-89:****
90-99:**
100:*
https://ideone.com/1g69oo
language:
Java (12.0.1)
created:
6 years ago
visibility:
public

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