java语言程序设计基础篇第一章编程练习题

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1：public class Test{public static void main(String[] args){System.out.println("Welcome to Java");System.out.println("Welcome to Computer Science");System.out.println("Programming is fun");}}2：public class Test{public static void main(String[] args){for(int i = 0; i < 5; ++i)System.out.println("Welcome to Java");}}3：public class Test{public static void main(String[] args){System.out.println("   J     A   V     V   A");System.out.println("   J    A A   V   V   A A");System.out.println("J  J   AAAAA   V V   AAAAA");System.out.println(" JJ   A     A   V   A     A");}}4：import java.util.Scanner;public class Test{public static void main(String[] args){Scanner input = new Scanner(System.in);char[] temp = new char[10];int num;for(int i = 0; i < 5; ++i){String Stemp;Stemp = input.next();temp = Stemp.toCharArray();if(temp[0] >= 'a' && temp[0] <= 'z'){System.out.println(temp[0]+"    "+temp[0]+"^2    " + temp[0] + "^3");}else if(temp[0] >= '0' && temp[0] <= '9'){num = temp[0] - '0';System.out.println(num+"    "+(int)Math.pow(num, 2)+"    "+(int)Math.pow(num, 3));}}}}5：import java.util.Scanner;public class Test{public static void main(String[] args){double result = (9.5*4.5-2.5*3)/(45.5-3.5);System.out.print(result);}}6：import java.util.Scanner;public class Test{public static void main(String[] args){int[] num = new int[9];for(int i = 0; i < 9; ++i)num[i] = i+1;int sum = 0;for(int i = 0; i < 9; ++i)sum += num[i];System.out.println(sum);}}7：import java.util.Scanner;public class Test{public static void main(String[] args){double pi1 = calculate(6);double pi2 = calculate(7);System.out.println(pi1);System.out.println(pi2);}public static double calculate(double n){double sum = 0.0;double num = 1;double a = 1;for(int i = 1; i <= n; ++i){sum += a*(1/num);num += 2;a = -a;}return 4.0*sum;}}8：import java.util.Scanner;public class Test{public static void main(String[] args){double radius = 5.5;double d = 2.0*Math.PI*radius;double s = Math.PI*Math.pow(radius, 2.0);System.out.println(d);System.out.println(s);}}9：import java.util.Scanner;public class Test{public static void main(String[] args){double height = 7.9;double width = 4.5;double s = height*width;System.out.println(s);}}10：import java.util.Scanner;public class Test{public static void main(String[] args){double mile = 14 / 1.6;double hour = 45.5/60;System.out.println(mile/hour);}}11：import java.util.Scanner;public class Test{public static void main(String[] args){long bornPerson,deadPerson,mobilePerson;long year = 5;long basicPerson = 312032486;long oneYearSeconds = 365*24*60*60;bornPerson = year*oneYearSeconds/7;deadPerson = year*oneYearSeconds/13;mobilePerson = year*oneYearSeconds/45;System.out.println(bornPerson + mobilePerson - deadPerson + basicPerson);}}12：和第10个差不多13：import java.util.Scanner;public class Test{public static void main(String[] args){System.out.println("3.4x + 50.2y = 44.5");System.out.println("2.1x + 0.55y = 5.9");double a,b,c,d,e,f;a = 3.4;b = 50.2;c = 2.1;d = 0.55;e = 44.5;f = 5.9;double x = (e*d - b*f)/(a*d - b*c);double y = (a*f - e*c)/(a*d - b*c);System.out.println("x:" + x + " " + "y:" + y);}}
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