3-27

简单计时器：

package com.example.wang3.myapplication;

import android.os.Handler;
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.EditText;
import android.widget.TextView;

public class ThreadActivity extends AppCompatActivity implements View.OnClickListener {
    private Button button;
    private TextView textView;
    private EditText editText;
    private int num1;
    private String num;
    private  Handler handler=new Handler(){
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            int arg1=msg.arg1;
            String info= (String) msg.obj;
            if (msg.what==1){
                textView.setText(info+arg1);
            }
            if (arg1==0){
                textView.setText("完成");
            }
        }
    };

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


    }

    private void BlindID() {
        button=findViewById(R.id.theradbtn);
        textView=findViewById(R.id.theradtext);
        editText=findViewById(R.id.theradedtext);
        button.setOnClickListener(this);

    }

    @Override
    public void onClick(View view) {
        switch (view.getId()){

            case R.id.theradbtn:
                num=editText.getText().toString();
                num1=Integer.parseInt(num);
                textView.setText("倒计时："+num1);
                new Thread(new Runnable() {
                    @Override
                    public void run() {
                       for (int i=num1;i >=0;i--) {
                           try {
                               Thread.sleep(1000);
                           } catch (InterruptedException e) {
                               e.printStackTrace();
                           }
                           Message message=handler.obtainMessage();
                           message.what=1;
                           message.arg1=i;
                           message.obj="倒计时：";
                           handler.sendMessage(message);

                       }
                    }
                }).start();
                break;
        }

    }
}