Handler——倒计时

Handler——倒计时

1.布局

<RelativeLayout 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=".activity.MainActivity">

    <ImageView
        android:id="@+id/img"
        android:src="@drawable/d"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
    <TextView
        android:id="@id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
</RelativeLayout>

2.实现

ublic class SecondActivity extends AppCompatActivity {

    private RadioGroup radioGroup;
    private int i=3;
    private TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
        textView = (TextView)findViewById(R.id.text);
        handler.sendEmptyMessageDelayed(0,1000);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        handler.removeCallbacksAndMessages(null);
    }

    Handler handler=new Handler(){
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch (msg.what){
                case 0:
                    if (i>0){
                        i--;
                        textView.setText(""+i);
                        handler.sendEmptyMessageDelayed(0,1000);
                    }else {
                        Intent intent=new Intent(SecondActivity.this,ThreeActivity.class);
                        startActivity(intent);
                        finish();
                    }
                    break;
            }
        }
    };
}