import javax.swing.JFormattedTextField; //导入方法依赖的package包/类

/**

* Constructor.

*/

public MassValueEntryNode( final BalanceGameModel balanceGameModel, PCanvas canvas ) {

this.model = balanceGameModel;

this.canvas = canvas;

// Add the textual prompt.

PText prompt = new PText( BalanceAndTorqueStudyResources.Strings.MASS_EQUALS );

prompt.setFont( TEXT_FONT );

// Create the sub-panel that will contain the edit box for entering

// the numerical value.

JPanel numericalValueEntryPanel = new JPanel();

numericalValueEntryPanel.setBackground( BACKGROUND_COLOR );

numberEntryField = new JFormattedTextField( NumberFormat.getNumberInstance() );

numberEntryField.setColumns( ANSWER_ENTRY_FIELD_COLUMNS );

numberEntryField.setFont( TEXT_FONT );

numberEntryField.setBorder( BorderFactory.createEtchedBorder() );

numberEntryField.requestFocus();

numericalValueEntryPanel.add( numberEntryField );

// Add the units label.

PText unitsLabel = new PText( BalanceAndTorqueStudyResources.Strings.KG );

unitsLabel.setFont( TEXT_FONT );

// Add a handler for the case where the user presses the Enter key.

numberEntryField.addActionListener( new ActionListener() {

public void actionPerformed( ActionEvent arg0 ) {

submitProposedAnswer();

}

} );

// Wrap the value entry panel in a PSwing.

PSwing valueEntryPSwing = new PSwing( numericalValueEntryPanel );

// Create the button for checking the answer.

checkAnswerButton = new TextButtonNode( BalanceAndTorqueStudyResources.Strings.CHECK_ANSWER, new PhetFont( 20 ), Color.YELLOW );

// Register to send the user's guess when the button is pushed.

checkAnswerButton.addActionListener( new ActionListener() {

public void actionPerformed( ActionEvent e ) {

submitProposedAnswer();

}

} );

// Lay out the node.

addChild( new ControlPanelNode( new VBox( 10, new HBox( 5, prompt, valueEntryPSwing, unitsLabel ), checkAnswerButton ), BACKGROUND_COLOR ) );

}