<LinearLayout     android:layout_width="match_parent"     android:layout_height="match_parent"    xmlns:android="http://schemas.android.com/apk/res/android">        <EditText         android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:id="@+id/etNum"        android:hint="input"        android:selectAllOnFocus="true"        />    <Button         android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="按下去"        android:id="@+id/btn"/></LinearLayout>

package com.example.deemo;import java.util.ArrayList;import java.util.List;import android.app.Activity;import android.os.Bundle;import android.os.Handler;import android.os.Looper;import android.os.Message;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;import android.widget.Toast;public class MainActivity extends Activity {        static final String UPPER_NUM = "upper";    EditText etNum;    CalThread calThread;    private Button button;        //定义一个线程类    class CalThread extends Thread{        public Handler mHandler;        public void run(){//执行方法            Looper.prepare();                        mHandler = new Handler(){                //定义消息处理方法                @Override                public void handleMessage(Message msg){                    if(msg.what == 0x123){                        int upper = msg.getData().getInt(UPPER_NUM);                        List<Integer> nums = new ArrayList<Integer>();                                                //计算方法                        outer:                            for (int i = 2; i <= upper; i++) {                                for (int j = 2; j <= Math.sqrt(i); j++) {                                    if(i != 2 && i%j ==0){                                        continue outer;                                    }                                }                                nums.add(i);                            }                        Toast.makeText(MainActivity.this, nums.toString(), Toast.LENGTH_LONG).show();;                    }                }            };            Looper.loop();        }    }        @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        etNum = (EditText) findViewById(R.id.etNum);        calThread = new CalThread();        calThread.start();//启动新线程        initClick();//点击事件           }    private void initClick() {        button = (Button) findViewById(R.id.btn);        button.setOnClickListener(new OnClickListener() {                        @Override            public void onClick(View arg0) {                //创建消息                Message msg = new Message();                msg.what = 0x123;                Bundle bundle = new Bundle();                bundle.putInt(UPPER_NUM, Integer.parseInt(etNum.getText().toString()));                msg.setData(bundle);                //向新线程中发送消息                calThread.mHandler.sendMessage(msg);            }        });        }}