use JList for history instead of JTextField

src/GFrame.java

@@ -14,6 +14,7 @@ import java.awt.event.*;
 import java.awt.*;
 import javax.swing.border.Border;
 import java.text.DecimalFormat;
+import java.lang.StringBuilder;
 
 class RoundBtn implements Border {
     private int r;
@@ -76,17 +77,15 @@ public class GFrame extends JFrame {
         tf.setFont((new Font("Times New Roman", Font.PLAIN, 20)));
         tf.setBorder(new RoundBtn(5));
 
-        // History Text Field
+        // History
-        History history = new History();
+        DefaultListModel<String> histList = new DefaultListModel<>();
-        JTextArea tHist = new JTextArea();
+        JList<String> lHist = new JList<>(histList);
-        tHist.setBounds(380, 50, 200, 240);
+        lHist.setBackground(Color.decode("#2B2B2B"));
-        tHist.setEditable(false);
+        lHist.setForeground(Color.decode("#e5e5e5"));
-        tHist.setBorder(new RoundBtn(5));
+        lHist.setBounds(380, 50, 200, 240);
-        tHist.setBackground(Color.decode("#2B2B2B"));
+        lHist.setFont(new Font("Times New Roman", Font.PLAIN, 20));
-        tHist.setForeground(Color.decode("#e5e5e5"));
+        lHist.setBorder(new RoundBtn(5));
-        tHist.setFont((new Font("Times New Roman", Font.PLAIN, 20)));
+        this.add(lHist);
-        tHist.setBorder(new RoundBtn(5));
-        tHist.setMargin(new Insets(0, 10, 0, 10));
 
         // Buttons
         JButton bEval = newButton("=", 290, 50, 60, 40);
@@ -137,7 +136,6 @@ public class GFrame extends JFrame {
         this.add(bEight);
         this.add(bNine);
         this.add(tf);
-        this.add(tHist);
         this.setSize(600, 400);
         this.setLayout(null);
         this.setVisible(true);
@@ -157,16 +155,15 @@ public class GFrame extends JFrame {
                     p = new Parser(tf.getText());
                     String formattedResult = format.format(p.eval());
                     tf.setText(formattedResult);
+                    String formattedExpr = expression + " = " + formattedResult;
 
-                    tHist.setText("");
+                    // Dont add to history if its already present in histList
-                    Vector<String> s = history.getHistory();
+                    for (int i = 0; i < histList.size(); i++) {
-                    s.add(expression + " = " + formattedResult);
+                        if (histList.get(i).equals(formattedExpr)) {
-                    for (int i = 0; i < s.size(); i++) {
+                            return;
-                        // tHist.setText(new String(s.get(i).concat(tHist.getText())).concat("\n"));
-                        tHist.append(s.get(i));
-                        tHist.append("\n");
                         }
-
+                    }
+                    histList.addElement(formattedExpr);
                 } else {
                     tf.setText("No input");
                 }
@@ -201,8 +198,7 @@ public class GFrame extends JFrame {
 
         bClearHistory.addActionListener(new ActionListener() {
             public void actionPerformed(ActionEvent e) {
-                history.clearHistory();
+                histList.clear();
-                tHist.setText("");
             }
         });
 
@@ -213,6 +209,26 @@ public class GFrame extends JFrame {
             }
         });
 
+        lHist.addMouseListener(new MouseAdapter() {
+            public void mouseClicked(MouseEvent evt) {
+                JList list = (JList) evt.getSource();
+                if (evt.getClickCount() == 2) {
+                    // Double-click detected
+                    int index = list.locationToIndex(evt.getPoint());
+                    String expr = histList.get(index);
+                    StringBuilder str = new StringBuilder("");
+                    int endIndex = 0;
+                    for (int i = 0; i < expr.length(); i++) {
+                        if (expr.charAt(i) == '=') {
+                            break;
+                        }
+                        endIndex++;
+                    }
+                    tf.setText(expr.substring(0, endIndex));
+                }
+            }
+        });
+
         // bOne.addActionListener(new ActionListener() {
         // public void actionPerformed(ActionEvent e) {
         // tf.setText(tf.getText() + "1");

src/History.java

@@ -1,17 +0,0 @@
-import java.util.Vector;
-
-public class History {
-    private Vector<String> hist;
-
-    History() {
-        hist = new Vector<String>();
-    }
-
-    public void clearHistory() {
-            hist.clear();
-    }
-
-    public Vector<String> getHistory() {
-        return hist;
-    }
-}