A-M baby

Task/GUI-enabling-disabling-of-controls/Java/gui-enabling-disabling-of-controls.java

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+import java.awt.GridLayout;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+import java.awt.event.KeyEvent;
+import java.awt.event.KeyListener;
+
+import javax.swing.JButton;
+import javax.swing.JFrame;
+import javax.swing.JPanel;
+import javax.swing.JTextField;
+import javax.swing.SwingUtilities;
+
+public class Interact extends JFrame{
+	final JTextField numberField;
+	final JButton incButton, decButton;
+	
+	public Interact(){
+		//stop the GUI threads when the user hits the X button
+		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+		
+		numberField = new JTextField();
+		incButton = new JButton("Increment");
+		decButton = new JButton("Decrement");
+		
+		numberField.setText("0");//start at 0
+		decButton.setEnabled(false);//we're already at 0
+		
+		//listen for button presses in the text field
+		numberField.addKeyListener(new KeyListener(){
+			@Override
+			public void keyTyped(KeyEvent e) {
+				//if the entered character is not a digit
+				if(!Character.isDigit(e.getKeyChar())){
+					//eat the event (i.e. stop it from being processed)
+					e.consume();
+				}else if(Character.isDigit(e.getKeyChar())){
+					//This method is executed from the event thread and updating the GUI
+					//from there doesn't always work. invokeLater will ensure that the
+					//GUI is updated
+					SwingUtilities.invokeLater(new Runnable() {
+						@Override
+						public void run() {
+							String text = numberField.getText();
+							if(text.isEmpty()){//default to 0 when all text is erased
+								numberField.setText("0");
+								decButton.setEnabled(false);
+								incButton.setEnabled(true);
+								return;
+							}
+							if(Long.valueOf(text) <= 0){
+								decButton.setEnabled(false);
+								incButton.setEnabled(true);
+							}else if(Long.valueOf(text) >= 10){
+								incButton.setEnabled(false);
+								decButton.setEnabled(true);
+							}else{
+								incButton.setEnabled(true);
+								decButton.setEnabled(true);
+							}
+						}
+					});
+				}
+			}
+			@Override
+			public void keyReleased(KeyEvent e){}
+			@Override
+			public void keyPressed(KeyEvent e){
+				//backspace and delete don't register in keyTyped because they don't
+				//display a Unicode character, so they must be handled here
+				if(e.getKeyCode() == KeyEvent.VK_BACK_SPACE ||
+						e.getKeyCode() == KeyEvent.VK_DELETE){
+					SwingUtilities.invokeLater(new Runnable() {
+						@Override
+						public void run() {
+							String text = numberField.getText();
+							if(text.isEmpty()){
+								numberField.setText("0");
+								decButton.setEnabled(false);
+								incButton.setEnabled(true);
+								return;
+							}
+							if(Long.valueOf(text) <= 0){
+								decButton.setEnabled(false);
+								incButton.setEnabled(true);
+							}else if(Long.valueOf(text) >= 10){
+								incButton.setEnabled(false);
+								decButton.setEnabled(true);
+							}else{
+								incButton.setEnabled(true);
+								decButton.setEnabled(true);
+							}
+						}
+					});
+				}
+			}
+		});
+		
+		//listen for button clicks on the increment button
+		incButton.addActionListener(new ActionListener(){
+			@Override
+			public void actionPerformed(ActionEvent e) {
+				String text = numberField.getText();
+				numberField.setText((Long.valueOf(text) + 1) + "");
+				if(Long.valueOf(text) + 1 >= 10){
+					incButton.setEnabled(false);
+				}
+				
+				if(Long.valueOf(text) + 1 > 0){
+					decButton.setEnabled(true);
+				}
+			}
+		});
+		
+		//listen for button clicks on the random button
+		decButton.addActionListener(new ActionListener(){
+			@Override
+			public void actionPerformed(ActionEvent e) {
+				String text = numberField.getText();
+				numberField.setText((Long.valueOf(text) - 1) + "");
+				if(Long.valueOf(text) - 1 <= 0){
+					decButton.setEnabled(false);
+				}
+				
+				if(Long.valueOf(text) - 1 < 10){
+					incButton.setEnabled(true);
+				}
+			}
+		});
+		
+		//arrange the components in a grid with 2 rows and 1 column
+		setLayout(new GridLayout(2, 1));
+		
+		//a secondary panel for arranging both buttons in one grid space in the window
+		JPanel buttonPanel = new JPanel();
+		
+		//the buttons are in a grid with 1 row and 2 columns
+		buttonPanel.setLayout(new GridLayout(1, 2));
+		//add the buttons
+		buttonPanel.add(incButton);
+		buttonPanel.add(decButton);
+		
+		//put the number field on top of the buttons
+		add(numberField);
+		add(buttonPanel);
+		//size the window appropriately
+		pack();
+		
+	}
+
+	public static void main(String[] args){
+		new Interact().setVisible(true);
+	}
+}