实验九 工具类一.doc

实验九：工具类一（验证性 2学时）1掌握封装类的用法阅读如下程序并运行之，体会封装类的意义及相关用法：public class fuzhuang public static void main(String args) int i1=10;float f1=3.14f;double d1=3.1415926;Integer I1=new Integer(i1);/生成Integer类Float F1=new Float(f1);/生成Float类Double D1=new Double(d1); /生成Double类 String si1=I1.toString();/分别调用包装类的toString()方法转换为字符串String sf1=F1.toString();String sd1=D1.toString();System.out.println(si1+si1);System.out.println(sf1+sf1);System.out.println(sd1+sd1); 2 掌握使用Math类的用法定义名为numberplay的类，在main方法中，定义一个double类型变量num1，初始化为34.7889定义一个变量num2并初始化为36.0.使用相应方法计算num2的平方根。使用Math.round(num1)计算最接近num1的整数.，使用判断两者之间的较大值3）编写应用程序，定义一个一维数组（12个元素）并随机赋值，排序后输出，要求每行输出4个数4）编写应用程序，定义一个二维数组并赋值，显示二维数组每行的元素值，并求所有元素的和并输出。5编写应用程序，定义一个44的二维数组并随机赋值，按行列输出，求最外圈之和，求主对角线中最大值及位置。5) 研究下述程序，体会向量import java.util.*;public class testvector public static void main(String args) Vector myvector1=new Vector(1); System.out.println(myvector1.capacity(); myvector1.addElement(hello); myvector1.addElement(java); System.out.println(myvector1.capacity(); System.out.println(myvector1); String s1=(String )myvector1.elementAt(1); System.out.println(s1); Vector myvector=new Vector(); for(int i=0;i3;i+) myvector.addElement(welcome); myvector.addElement(to); myvector.addElement(beijing); System.out.println(myvector.size(); for(int i=0;imyvector.size();i+) String s=(String )myvector.elementAt(i); System.out.print(s+ ); System.out.println(); while(myvector.removeElement(to); for(int i=0;imyvector.size();i+) String s=(String )myvector.elementAt(i); System.out.println(s); 6研究下述程序，体会数组和向量的不同用法。/ AssignGrade.java: Assign gradepublic class AssignGrade / Main method public static void main(String args) int numOfStudents = 0; / The number of students int scores; / Array scores int best = 0; / The best score char grade; / The grade / Get number of students System.out.println(Please enter number of students); numOfStudents = MyInput.readInt(); / Create array scores scores = new intnumOfStudents; / Read scores and find the best score System.out.println(Please enter + numOfStudents + scores); for (int i=0; i best) best = scoresi; / Assign and display grades for (int i=0; i= best - 10) grade = A; else if (scoresi = best - 20) grade = B; else if (scoresi = best - 30) grade = C; else if (scoresi = best - 40) grade = D; else grade = F; System.out.println(Student + i + score is + scoresi + and grade is + grade); / AssignGradeUsingVector.java: Assign gradeimport java.util.*;public class AssignGradeUsingVector / Main method public static void main(String args) Vector scoreVector = new Vector(); / Vector to hold scores double best = 0; / The best score char grade; / The grade / Read scores and find the best score System.out.println(Please enter scores. + A negative score terminates input.); do System.out.print(Please enter a new score: ); double score = MyInput.readDouble(); if (score best) best = score; while (true); System.out.println(There are total + scoreVector.size() + students ); / Assign and display grades for (int i=0; i= best - 10) grade = A; else if (score = best - 20) grade = B; else if (score = best - 30) grade = C; else if (score = best - 40) grade = D; else grade = F; System.out.println(Student + i + score is + score + and grade is + grade); / MyInput.java: Contain the methods for reading int, double, and/ string values from the keyboardimport java.io.*;public class MyInput / Read a string from the keyboard public static String readString() BufferedReader br = new BufferedReader(new InputStreamReader(System.in), 1); / Declare and initialize the string String string = ; / Get the string from the keyboard try string = br.readLine(); catch (IOException ex) System.out.println(ex); / Return the string obtained from the keyboard return string; / Read an int value from the keyboard public static int readInt() return Integer.parseInt(readString(); / Read a double value from the keyboard public static double readDouble() return Double.parseDouble(readString(); / Read a byte value from the keyboard public static byte readByte() return Byte.parseByte(readString(); / Read a short value from the keyboard public static short readShort() return Short.parseShort(readStrin