# java 回転行列

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Graphics2DTest1.java
```import javax.swing.*;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Insets;
import java.awt.geom.Line2D;

public class Graphics2DTest1 extends JPanel{
double x = 1;
double y = 400;

double r = 100;
double cx, cy;
double rx,ry;

double movex;
double movey;

double theta = 30;

public static void main(String[] args){
JFrame frame = new JFrame();

Graphics2DTest1 app = new Graphics2DTest1();
frame.setBackground(Color.BLACK);
frame.setResizable(false);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setBounds(0, 0, 400, 400);
frame.setTitle("タイトル");
frame.setVisible(true);
Insets insets = frame.getInsets();
frame.setSize(400 + insets.left + insets.right, 400 + insets.top + insets.bottom);
}

public void paintComponent(Graphics g){
Graphics2D g2 = (Graphics2D)g;
g.setColor(Color.white);
g.drawLine(0,200,400,200);
g.drawLine(200,0,200,400);
//array(g);
//Circle(g);
//oval(g);
rotation(g2);
}

public void array(Graphics2D g){
for(int i = 0; i <= 400; i++){
g.draw(new Line2D.Double(x + i ,y - i,x + i,y - i));
movex += 1;
movey -= 1;
}
}

public void Circle(Graphics2D g){
for(int i = 0; i < 360; i++){
cy = (int) (200 + Math.sin(i) * r);
cx = (int) (200 + Math.cos(i) * r);
g.draw(new Line2D.Double(cx, cy, cx, cy));
}
}

public void oval(Graphics2D g){
for(int i = 0; i < 360; i++){
cy = (int) (200 + Math.sin(i) * r / 2);
cx = (int) (200 + Math.cos(i) * r);
g.draw(new Line2D.Double(cx, cy, cx, cy));
}
}

public void rotation(Graphics2D g){
g.setColor(Color.yellow);
for(int i = 0; i < 12; i++){
double rx = 200 + (r * Math.cos((theta * i) / 180 * Math.PI));
double ry = 200 + (r * Math.sin((theta * i) / 180 * Math.PI));
g.draw(new Line2D.Double(rx, ry, rx, ry));
//g2.draw(new Line2D.Double(x, y, x, y));
System.out.println(i + "回目");
System.out.println("rx" + rx);
System.out.println("ry" + ry);
}
}
}
```

ターミナルで実行する場合は下のコマンドを打ってください。
\$ javac Graphics2DTest1.java
\$ java Graphics2DTest1