>>587
http://java-house.jp/ml/archive/j-h-b/024765.html#body
を参考にしてサンプルを作成。

import java.awt.BorderLayout;
import java.awt.event.*;
import java.lang.Character.UnicodeBlock;
import javax.swing.*;
public class Q_79_587 {
public static void main(String[] args) {
JFrame frm = new JFrame();
frm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
final JTextField tf1 = new JTextField("IM off");
frm.getContentPane().add(tf1);
final JTextField tf2 = new JTextField("全角ひらがな");
frm.getContentPane().add(tf2, BorderLayout.SOUTH);
final Character.Subset[] ss1 = {UnicodeBlock.HIRAGANA};
final Character.Subset[] ss2 = {UnicodeBlock.BASIC_LATIN};
tf1.addFocusListener(new FocusAdapter() {
public void focusGained(FocusEvent e) {
tf1.getInputContext().setCharacterSubsets(ss1);
}
});
tf2.addFocusListener(new FocusAdapter() {
public void focusGained(FocusEvent e) {
tf2.getInputContext().setCharacterSubsets(ss2);
}
});
frm.pack();
frm.setVisible(true);
}
}