HandlerDemo

circle.png

package com.xxx.handlerdemo;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.SystemClock;
import android.util.DisplayMetrics;
import android.widget.ImageView;
import android.widget.TextView;

public class MainActivity extends Activity {

    private ImageView imageView1;
    private int marginLeft = 0;
    private int marginBottom = 0;

    private Handler handler = new Handler() {
        public void handleMessage(android.os.Message msg) {
            switch (msg.what) {
            case 0:
                if (marginLeft == screenWidth) {
                    marginBottom = marginBottom > screenHeight ? 0
                            : (marginBottom + 30);
                }
                marginLeft = marginLeft == screenWidth ? 0 : (marginLeft + 1);
                // marginLeft = 1;

                // imageView1.offsetLeftAndRight(marginLeft);
                imageView1.setX(marginLeft);
                imageView1.setY(marginBottom);
                textView1.setText("" + marginLeft + ":" + marginBottom);
                break;

            default:

                break;
            }

        };
    };

    private int screenWidth;
    private int screenHeight;
    private TextView textView1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        DisplayMetrics metrics = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(metrics);

        screenHeight = metrics.heightPixels;
        screenWidth = metrics.widthPixels;

        imageView1 = (ImageView) findViewById(R.id.imageView1);
        textView1 = (TextView) findViewById(R.id.textView1);
        new Thread() {
            public void run() {
                while (true) {
                    SystemClock.sleep(1);

                    handler.sendEmptyMessage(0);
                }
            };
        }.start();
    }

}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >

<ImageView
    android:id="@+id/imageView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:src="@drawable/circle" />

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_marginLeft="158dp"
    android:layout_toRightOf="@+id/imageView1"
    android:text="TextView" />

</RelativeLayout>