Java课后答案题.docVIP

同心圆 package bookback; import java.applet.Applet; import java.awt.Graphics; public class TestApplet extends Applet{ private static final long serialVersionUID = 1L; public void paint(Graphics g){ g.drawOval(50, 50, 100, 100); g.drawOval(20, 20, 160, 160); g.drawString(同心, 90, 105); } } 三角形 @Java实现 package bookback; public class DrawTri { public static void main(String[] args){ for(int i = 1;i 4;i++){ for(int j = 1;j = 4 - i;j++){ System.out.print( );} for(int x = 1;x = i*2-1;x++){ System.out.print(*);} System.out.println(); }}} @Applet实现 import java.applet.Applet; import java.awt.Graphics; public class PrintXingApplet extends Applet{ static void draw(int n , Graphics g){ for (int i = 0; i n; i++){ String space = ; String xing = ; for (int j = 0; j n -1-i; j++){ space += ;} for (int k = 0; k 2 * (i + 1) - 1; k++){ xing += *;} g.drawString(space+xing,0, *(i+1)); }} public void paint(Graphics g) { draw(3,g);}} 球的体积 package bookback; public class Ball { public static void main(String[] args){ int a = 2; a = 6;int b = 7,c = 8; double d = 3.14; String x = hello; System.out.println(a+b+x+c+d); double r = 2; double v = Sphere(r); System.out.println(v); } public static double Sphere(double r){ double PI = 3.141592653; double v = (4*PI*r*r*r)/3; return v; }} 矩形周长和面积 package bookback; import java.util.Scanner; public class Rectangle { public static void main(String[] args){ Scanner in = new Scanner(System.in); System.out.println(Please input the length of the rectangle:); int l = in.nextInt(); System.out.println(Please input the width of the rectangle:); int w = in.nextInt(); double a = area(l,w); double p = perimeter(l,w); System.out.println(The area of the rectangle is +a); System.out.println(The perimeter of the rectangle is +p); } public static double area(double l,double w){ double a = l * w; return a; } Public static double perimeter(double l,double w){ double p = 2 * (l + w); return p;}} 奇偶数 package bookback; i