Implement basic display of values

Author: hhontheim

src/main/java/net/hontheim/MainApp.java

@@ -1,20 +1,93 @@
 package net.hontheim;
 
 import javafx.application.Application;
+import javafx.event.ActionEvent;
+import javafx.event.EventHandler;
+import javafx.geometry.Insets;
+import javafx.geometry.Pos;
 import javafx.scene.Scene;
+import javafx.scene.control.Button;
 import javafx.scene.control.Label;
 import javafx.scene.layout.GridPane;
 import javafx.stage.Stage;
 
+import java.io.IOException;
+import java.nio.ByteBuffer;
+
 public class MainApp extends Application {
 
+    private GridPane pane = new GridPane();
+    private Label lblTitle, lblDirectAllocation, lblNativeUsed, lblmaxMemory;
+    private Label valDirectAllocation, valNativeUsed, valmaxMemory;
+    private Button btnUpdate, btnReopen;
+
+    private static ByteBuffer humonguosBuffer = ByteBuffer.allocateDirect(1024*1024*1024);
+
     public static void main(String[] args) {
         launch(args);
     }
 
     @Override
     public void start(Stage stage) throws Exception {
-        stage.setScene(new Scene(new GridPane(), 160, 90));
+        stage.setTitle("Java Memory");
+        this.initializeComponents();
+        this.updateValues();
+        this.placeComponents(stage);
+        this.registerListener();
+        stage.setResizable(false);
         stage.show();
     }
+
+    private void initializeComponents() {
+        lblTitle = new Label("Java Memory");
+        lblTitle.setStyle("-fx-font-size: 18; -fx-font-weight: bold;");
+
+        lblDirectAllocation = new Label("Direct allocation:");
+        lblNativeUsed = new Label("Native memory used:");
+        lblmaxMemory = new Label("Max direct memory:");
+
+        valDirectAllocation = new Label();
+        valNativeUsed = new Label();
+        valmaxMemory = new Label();
+
+        btnUpdate = new Button("Update");
+        btnUpdate.setDefaultButton(true);
+    }
+
+    private void placeComponents(Stage stage) {
+        pane.setHgap(10);
+        pane.setVgap(10);
+        pane.setPadding(new Insets(15, 25, 15, 25));
+
+        pane.add(lblTitle, 0, 0, 2, 1);
+
+        pane.add(lblDirectAllocation, 0, 2);
+        pane.add(lblNativeUsed, 0, 3);
+        pane.add(lblmaxMemory, 0, 4);
+
+        pane.add(valDirectAllocation, 1, 2);
+        pane.add(valNativeUsed, 1, 3);
+        pane.add(valmaxMemory, 1, 4);
+
+        pane.add(btnUpdate, 0, 6);
+
+        pane.setAlignment(Pos.CENTER);
+
+        stage.setScene(new Scene(pane, 300, 250));
+    }
+
+    private void registerListener() {
+        btnUpdate.setOnAction(new EventHandler<ActionEvent>() {
+            @Override
+            public void handle(ActionEvent event) {
+                updateValues();
+            }
+        });
+    }
+
+    private void updateValues() {
+        this.valDirectAllocation.setText("" + humonguosBuffer.capacity());
+        this.valNativeUsed.setText("" + sun.misc.SharedSecrets.getJavaNioAccess().getDirectBufferPool().getMemoryUsed());
+        this.valmaxMemory.setText("" + sun.misc.VM.maxDirectMemory());
+    }
 }