多线程

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.hanqi.testapp2.TestActivity6"
    android:orientation="vertical">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="城市1"
        android:id="@+id/tv_3"/>

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="城市2"
        android:id="@+id/tv_4"/>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="启动"
        android:onClick="bt1_OnClick"/>
</LinearLayout>

package com.hanqi.testapp2;

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

import java.util.Random;


public class TestActivity6 extends AppCompatActivity {

    TextView tv_3;
    TextView tv_4;
@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_test6);

        tv_3=(TextView)findViewById(R.id.tv_3);
        tv_4=(TextView)findViewById(R.id.tv_4);
}
String c1="北京";
    String c2="香港";

    public void bt1_OnClick(View v)
    {
        tv_3.setText("");
        tv_4.setText("");


        //创建子线程1
        new Thread(){

            @Override
            public void run() {


                for (int i=0;i<10;i++)
                {

                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {


                            tv_3.setText(tv_3.getText()+c1);
                }
                    });


                    try {
                        //暂停时间随机
                        Thread.sleep(new Random().nextInt(2000));
                    }
                    catch (Exception e)
                    {

                    }
                }
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {

                        Toast.makeText(TestActivity6.this,c1+ "循环完成", Toast.LENGTH_SHORT).show();

                    }
                });


            }
        }.start();

        //创建子线程2  实现接口
        new Thread(){

            @Override
            public void run() {


                for (int i=0;i<10;i++)
                {

                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {


                            tv_4.setText(tv_4.getText()+c2);
                        }
                    });


                    try {
                        //暂停时间随机
                        Thread.sleep(new Random().nextInt(2000));
                    }
                    catch (Exception e)
                    {

                    }
                }
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {

                        Toast.makeText(TestActivity6.this,c2+ "循环完成", Toast.LENGTH_SHORT).show();

                    }
                });


            }
        }.start();
    }

}