Javaサンプル(テキストフィールド配列と棒グラフ)

//Sample05
import java.awt.Button;
import java.awt.FlowLayout;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.TextField;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
public class Sample05 extends Frame implements ActionListener {
  private static final long serialVersionUID = 4392385647873054409L;
  private static final int origin_X = 100;
  private static final int origin_Y = 300;
  private static final int rect_pitch = 40;
  private static final int rect_width = 10;
  private static final int tf_size = 3;
  private static final String init_value = "100";
  private static final String btn_title = "Graph";
  private static final String window_title = "テキストフィールド配列と棒グラフ";
  private static final int window_width = 640;
  private static final int window_height = 400;
  TextField[] tf = new TextField[12];
  // 主処理
  public static void main(final String ar[]) {
    final Frame f = new Sample05();
    f.setTitle(Sample05.window_title);
    f.setSize(Sample05.window_width, Sample05.window_height);
    f.setVisible(true);
  }
  // 部品セット
  Sample05() {
    this.setLayout(new FlowLayout());
    final Button btn = new Button(Sample05.btn_title);
    btn.addActionListener(this);
    for (int i = 0; i < this.tf.length; i++) {
      this.tf[i] = new TextField(Sample05.init_value, Sample05.tf_size);
      this.add(this.tf[i]);
    }
    this.add(btn);
    this.addWindowListener(new WinAdapter());
  }
  // 閉じる
  class WinAdapter extends WindowAdapter {
    @Override
    public void windowClosing(final WindowEvent we) {
      System.exit(0);
    }
  }
  // 描画
  @Override
  public void paint(final Graphics g) {
    g
        .clearRect(0, 0, Sample05.window_width - 1,
            Sample05.window_height - 1);
    for (int i = 0; i < this.tf.length; i++) {
      final String rs = this.tf[i].getText();
      if (rs != null) {
        try {
          final int rect_height = Integer.parseInt(rs);
          g.drawRect(Sample05.origin_X + i * Sample05.rect_pitch,
              Sample05.origin_Y - rect_height,
              Sample05.rect_width, rect_height);
        } catch (final NumberFormatException e) {
        }
      }
    }
  }
  // イベント
  public void actionPerformed(final ActionEvent ae) {
    if (ae.getActionCommand() == Sample05.btn_title) {
      this.repaint();
    }
  }
}