倒计时完整步骤

一、

<ImageView
        android:id=\"@+id/imageView\"
        android:scaleType=\"fitXY\"
        android:layout_width=\"match_parent\"
        android:layout_height=\"match_parent\"
        android:layout_weight=\"1\"
        app:srcCompat=\"@mipmap/ic_lunager\" />

    <TextView
        android:id=\"@+id/textView1\"
        android:layout_width=\"wrap_content\"
        android:layout_height=\"wrap_content\"
        android:layout_alignParentTop=\"true\"
        android:layout_alignParentEnd=\"true\"
        android:layout_marginTop=\"26dp\"
        android:layout_marginEnd=\"26dp\"
        android:text=\"TextView\" />

二、Activity

package bwhttp.com.monthexam;

import android.content.Intent;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ImageView;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    public int time;
    private ImageView imageView;
    private TextView textView;
    private Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            if (time == 0){
                startActivity(new Intent(MainActivity.this,Main2Activity.class));
                finish();
                return;
            }
            time--;
            textView.setText(\"倒计时：\"+time+\"s\");
            handler.sendEmptyMessageDelayed(0,1000);
        }
    };

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

        imageView = findViewById(R.id.imageView);
        textView = findViewById(R.id.textView1);

        time = 3;
        textView.setText(\"倒计时：\"+time+\"s\");
        handler.sendEmptyMessageDelayed(0,1000);

    }
}