[Android] Handler時間

前面一定要先加入

implements Runnable

public class MainActivity extends AppCompatActivity  implements Runnable{

示範

XML

xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/t1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:text="TextView"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

android.support.constraint.ConstraintLayout>

JAVA

public class MainActivity extends AppCompatActivity  implements Runnable{
TextView t1;
    private Handler handler;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
t1=(TextView)findViewById(R.id.t1);
        handler = new Handler() {
            public void handleMessage(Message msg) {
                t1.setText((String)msg.obj);
            }
        };
        new Thread(this).start();
    }
    @Override
    public void run() {
        // TODO Auto-generated method stub
        try {
            while (true) {
                SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ssaa");//時間格式
                String str = sdf.format(new Date());
                handler.sendMessage(handler.obtainMessage(100, str));
                Thread.sleep(1000);
            }
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

展示

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