练习

package com.hanqi.testapp22;

import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.os.Handler;

public class TestActivity6 extends AppCompatActivity {

    TextView tv_5;
    TextView tv_6;
    Button bt_3,bt_4,bt_5;
 int i = 10;
    Handler hl=new Handler()
    {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch (msg.what)
            {
                case 1:

                    if (i==20)
                    {

                        bt_3.setEnabled(false);
                        bt_4.setEnabled(true);
                        bt_5.setEnabled(false);
                        return;
                    }
                    i++;
                    tv_6.setText(i + "");
                    hl.sendEmptyMessageDelayed(1, 2000);
                    hl.removeMessages(2);
                    bt_3.setEnabled(false);


                    break;
                case 2:
                    if (i==1)
                    {
                        bt_4.setEnabled(false);
                        bt_5.setEnabled(false);
                        bt_3.setEnabled(true);
                        return;
                    }
                    i--;
                    tv_6.setText(i+"");
                    hl.sendEmptyMessageDelayed(2,2000);
                    hl.removeMessages(1);
                    bt_4.setEnabled(false);

                    break;
                case 3:
                    if (i==10)
                    {
                        bt_5.setEnabled(false);
                    }
                    hl.removeMessages(1);
                    hl.removeMessages(2);
                    bt_5.setEnabled(false);
                    break;
            }
        }
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_test6);
        tv_5=(TextView)findViewById(R.id.tv_5);
        tv_6=(TextView)findViewById(R.id.tv_6);
        bt_3=(Button)findViewById(R.id.bt_3);
        bt_4=(Button)findViewById(R.id.bt_4);
        bt_5=(Button)findViewById(R.id.bt_5);
    }