update:demo11

com/study/demo11/TimeViewer.java

@@ -0,0 +1,45 @@
+package com.study.demo11;
+
+import java.awt.Frame;
+import java.awt.Label;
+import java.time.LocalDateTime;
+import java.time.format.DateTimeFormatter;
+
+public class TimeViewer extends Frame {
+    private Label timeLabel;
+    private DateTimeFormatter formatter;
+
+    public TimeViewer() {
+        super("系统时间显示器");
+        formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
+
+        timeLabel = new Label("", Label.CENTER);
+        add(timeLabel);
+
+        setSize(300, 100);
+        setLayout(new java.awt.FlowLayout());
+        setLocationRelativeTo(null);
+        setVisible(true);
+
+        updateTime();
+        startTimeUpdate();
+    }
+
+    private void updateTime() {
+        LocalDateTime now = LocalDateTime.now();
+        timeLabel.setText(now.format(formatter));
+    }
+
+    private void startTimeUpdate() {
+        new java.util.Timer().scheduleAtFixedRate(new java.util.TimerTask() {
+            @Override
+            public void run() {
+                updateTime();
+            }
+        }, 0, 1000);
+    }
+
+    public static void main(String[] args) {
+        new TimeViewer();
+    }
+}