maru.java

import java.awt.*;
import java.awt.event.*;

import javax.swing.JFrame;

public class Maru extends JFrame implements KeyListener, Runnable {
    public int width = 800, height = 600; // 画面サイズ
    public int x = width/2, y = height/2; // 主人公座標
    public int size = 50;                 // 円のサイズ
    public int range = 5;                 // 移動幅
    public int interval = 20;			  // 描画の間隔
    public boolean right = false;         // 右方向のフラグ
    public boolean left  = false;         // 左方向のフラグ
    
	public static void main(String[] args) {
        Maru f = new Maru();
    }

	public Maru() {
        //フレーム作成
        this.setSize(this.width, this.height);
        this.setVisible(true);
        addKeyListener(this);
        new Thread(this).start();
	}
	
    public void paint(Graphics g) {
        // 背景色で塗りつぶし
    	g.clearRect(0, 0, this.width, this.height);
    	// 円表示
        g.drawOval(this.x, this.y, this.size, this.size);
    }
    
    @Override
    public void update(Graphics g) {
    	paint(g);
    }

	@Override
	public void keyPressed(KeyEvent e) {
		// TODO Auto-generated method stub
		int key = e.getKeyCode();
		// 方向キーで制御
		if(key == KeyEvent.VK_RIGHT) {
			right = true;
			//x += this.range;
		} else if(key == KeyEvent.VK_LEFT) {
			//is.x -= this.range;
			left = true;
		} else if(key == KeyEvent.VK_UP) {
			this.y -= this.range;
		} else if(key == KeyEvent.VK_DOWN) {
			this.y += this.range;
		}
		// 画面の中に納まっているか判定
		if(this.x < 0) {
			this.x = 0;
		} else if (x > this.width - this.size) {
			this.x = this.width - this.size;
		} else if (y < 0) {
			this.y = 0;
		} else if (y > this.height - this.size) {
			this.y = this.height - this.size;
		}
		// paint()を実行
		//repaint();
	}

	@Override
	public void keyReleased(KeyEvent e) {
		// TODO Auto-generated method stub
		right = false;
		left  = false;
	}

	@Override
	public void keyTyped(KeyEvent e) {
		// TODO Auto-generated method stub

	}

	@Override
	public void run() {
		// TODO Auto-generated method stub
		while(true) {
			if(right) {
				x += range;
			}
			if(left) {
				x -= range;
			}
			repaint();
			try {
				Thread.sleep(interval);
			} catch(Exception e) {
				
			}
		}
	}
}