例で考えるJavaプログラミング (13)

progJ.pdf progJ-s.pdf progJ-e.pdf 記事一覧

カーソル位置の表示           （WinShot使用のためカーソルが枠外に移動）

progJ.pdf の[#62]－[#63]に対応する部分を追加しました．
※ *.class は http://hakurei-isl.org/m-miyata/jar/App62-dist.zip,
http://hakurei-isl.org/m-miyata/jar/App63-dist.zip,

//App62.java
import java.awt.*;
import java.awt.event.*;
public class App62 extends App61 {
    /* このように書くことが多いが構文が複雑．
    App62( ){super( );
        p1.addMouseMotionListener(new MouseAdapter( ){
            public void mouseMoved(MouseEvent e){
                tf1.setText(e.getX() +", "+ e.getY( ));
            }
        });
    }
    */
    //class MMA62 extends MouseMotionAdapter {
    class MA62 extends MouseAdapter {
     //MA62(){super(); /*追加なし*/}
       public void mouseMoved(MouseEvent e){
            tf1.setText(e.getX( ) +", "+ e.getY( ));
        }
    }
    App62( ){super( );
        p1.addMouseMotionListener(new MA62( ));
        //p1.addMouseAdapter(new MA62( ));エラー
        //p1.addMouseListener(new MMA62( ));無効
    }
}
------------------------------------------
//App63.java
import java.awt.*;
import javax.swing.*;
class Fig61 extends JPanel{
    Fig61( ){
        super( );
        setPreferredSize(new Dimension(300, 200));
        setBackground(Color.white);
    }
    public void paintComponent(Graphics g){
        super.paintComponent(g);
        g.drawLine(0,0,200,200);
        g.drawString("Hello", 50, 150);
        g.drawOval(150, 50, 100, 50);
        int x = 90, y = 200, dx = 10, dy;
        while(y <= 200){
            dy = (-2 * (150 - x) * dx)/25;
            g.drawLine(x, y, x + dx, y + dy);
            x += dx; y += dy;
        }//y = 56 - (150 - x)*(150 - x)/25
    }
}