Summary of Java Review

The moon goes round the earth. Write an application that simulates the moon turning around the earth.

Mainclass.java

Import javax.swing.*;
public class MainClass {
public static void Main (String args[]) {
Sky sky= New Sky (); Constructs a Sky (Tag object)
JFrame frame = new JFrame (); Constructs a framework (form)
Frame.settitle ("The moon Goes Around the earth");
Frame.add (Sky); Place the Sky (label) in the Frame (form)
Frame.setsize (400,300);
Frame.setvisible (TRUE);
Frame.setlocationrelativeto (NULL); Set the position of the form-centered
Frame.setdefaultcloseoperation (Jframe.exit_on_close);
Frame.getcontentpane (). SetBackground (Java.awt.Color.white); Convert the form to a container and set its background color to white
}
}

Earth.java

Import java.awt.*;
Import javax.swing.*;
Import java.awt.event.*;
public class Earth extends JLabel implements ActionListener {//Subclass of Tag class JLabel--portraying the Earth
JLabel Moon; Label class--depicting (showing) the appearance of the moon
Timer timer; Timer
Double pointx[]=new double[360],//double array pointx depicts horizontal coordinates-the moon is relative to the Earth's
Pointy[]=new double[360]; The double array pointy depicts the vertical coordinates-the moon is relative to the Earth
int w=200,h=200,i=0;
Earth () {
Timer=new Timer (20,this); Create timer, ring interval is 20 milliseconds current Earth object for its monitor
SetIcon (New ImageIcon ("earth.jpg")); Set the earth (label) icon to Earth.jpg
Sethorizontalalignment (Swingconstants.center); Set the earth (label) alignment to center
Moon=new JLabel (New ImageIcon ("Moon.jpg"), Swingconstants.center); Construct the Moon (label) object
Moon.setsize (60,60); Set the size of the Moon (label)
Add (moon); The Moon (the label) is placed in the label object depicting the Earth.
pointx[0]=0; The radius of the orbit of the moon H/2
POINTY[0]=H/2;
Double angle=1*math.pi/180; Scale is 1 degrees
for (int i=0;i<359;i++) {//calculates the value of each element in the array-the coordinate point on the circle
Pointx[i+1]=pointx[i]*math.cos (angle)-pointy[i]*math.sin (angle); Circle Center (0,0), first point (0,H/2), Shun time
Pointy[i+1]=pointy[i]*math.cos (angle) +pointx[i]*math.sin (angle); Coordinates after the needle rotates 1 radians
}
for (int i=0;i<360;i++) {
POINTX[I]=0.8*POINTX[I]+W/2; Coordinate zoom panning--Change Circle Center to (W/2,H/2)
POINTY[I]=0.8*POINTY[I]+H/2; Track circle size reduced by 1 time times
}
Timer.start (); Timer Start--fires every 100 milliseconds actionevent
}
public void actionperformed (ActionEvent e) {
I= (i+1)%360; 0~359 Cycle Changes
Moon.setlocation ((int) pointx[i]-30, (int) pointy[i]-30); Sets the position of the Moon Object (label) on the Earth Object (label)
}
}

Sky.java

Import java.awt.*;
Import javax.swing.*;
Import java.awt.event.*;
public class Sky extends JLabel implements ActionListener {//Subclass of Tag class JLabel--depicting the sky
Earth Earth;
Timer timer; Timer
Double pointx[]=new double[360],//double array pointx depicts horizontal coordinates-the Earth's relative to the sky
Pointy[]=new double[360]; The double array pointy depicts the vertical coordinates-the Earth's relative to the sky
int w=400,h=400,i=0;
Sky () {
Timer=new Timer (100,this); Create timer--ring interval is 100 milliseconds-the current Sky object is its monitor
earth = New Earth (); Constructs a globe (actually a label object)
Earth.setsize (200,200); Earth (Label object) size is 200*200
Add (earth); The earth is in the label that portrays the sky (the label can also be a container)
pointx[0]=0; The radius of the Earth's orbit H/2
POINTY[0]=H/2;
Double angle=1*math.pi/180; Scale is 1 degrees-radians
for (int i=0;i<359;i++) {//calculates the value of each element in the array-the coordinate point on the circle
Pointx[i+1]=pointx[i]*math.cos (angle)-pointy[i]*math.sin (angle); Circle Center (0,0), first point (0,H/2), Shun time
Pointy[i+1]=pointy[i]*math.cos (angle) +pointx[i]*math.sin (angle); Coordinates after the needle rotates 1 radians
}
for (int i=0;i<360;i++) {
POINTX[I]=0.5*POINTX[I]+W/2; Coordinate zoom panning--Change Circle Center to (W/2,H/2)
POINTY[I]=0.5*POINTY[I]+H/2; Track circle size reduced by 1 time times
}
Timer.start (); Timer Start--fires every 100 milliseconds actionevent
}
public void actionperformed (ActionEvent e) {
I= (i+1)%360; 0~359 Cycle Changes
Earth.setlocation ((int) pointx[i]-100, (int) pointy[i]-100); Set the Earth Object (label) position on the Sky Object (label)
}
}

Summary of Java Review