Android实现界面定时刷新功能

// ==============================================
// 文件：mainactivity.java
// 功能：演示五种方式实现界面定时刷新（实时时钟示例）
// 包含布局 xml、gradle 依赖一处整合，详细注释
// ==============================================
 
package com.example.timerrefresh;
 
import android.os.*;
import android.view.view;
import android.widget.button;
import android.widget.textview;
import androidx.appcompat.app.appcompatactivity;
 
// rxjava 依赖
import io.reactivex.rxjava3.android.schedulers.androidschedulers;
import io.reactivex.rxjava3.core.*;
import io.reactivex.rxjava3.disposables.disposable;
import io.reactivex.rxjava3.schedulers.schedulers;
 
// kotlin coroutines & flow 依赖（需 kotlin 支持）
// import kotlinx.coroutines.*
// import kotlinx.coroutines.flow.*
 
// java 并发
import java.text.simpledateformat;
import java.util.date;
import java.util.locale;
import java.util.timer;
import java.util.timertask;
import java.util.concurrent.*;
 
public class mainactivity extends appcompatactivity {
    private textview tvclock;
    private button btnstart, btnstop;
 
    // --- 方案 a: handler + postdelayed ---
    private handler handler = new handler(looper.getmainlooper());
    private runnable taska = new runnable() {
        @override public void run() {
            updatetime();
            handler.postdelayed(this, 1000);
        }
    };
 
    // --- 方案 b: timer + handler ---
    private timer timerb;
    private timertask timertaskb;
 
    // --- 方案 c: scheduledexecutorservice ---
    private scheduledexecutorservice schedulerc;
    private scheduledfuture<?> futurec;
 
    // --- 方案 d: rxjava interval ---
    private disposable disposabled;
 
    // --- 方案 e: kotlin coroutines + flow ---
    // private job jobe;
 
    @override
    protected void oncreate(bundle savedinstancestate) {
        super.oncreate(savedinstancestate);
        setcontentview(r.layout.activity_main);  // 布局整合在注释下方
 
        tvclock   = findviewbyid(r.id.tvclock);
        btnstart  = findviewbyid(r.id.btnstart);
        btnstop   = findviewbyid(r.id.btnstop);
 
        btnstart.setonclicklistener(v -> {
            // 选择下面一种，注释其余
            starta();
            // startb();
            // startc();
            // startd();
            // starte();
        });
        btnstop.setonclicklistener(v -> {
            stopa();
            stopb();
            stopc();
            stopd();
            stope();
        });
    }
 
    /** 更新时钟显示 */
    private void updatetime() {
        string now = new simpledateformat(
            "hh:mm:ss", locale.getdefault())
            .format(new date());
        tvclock.settext(now);
    }
 
    // === 方案 a：handler + postdelayed ===
    private void starta() {
        handler.post(taska);
    }
    private void stopa() {
        handler.removecallbacks(taska);
    }
 
    // === 方案 b：timer + handler ===
    private void startb() {
        timerb = new timer();
        timertaskb = new timertask() {
            @override public void run() {
                handler.post(() -> updatetime());
            }
        };
        timerb.scheduleatfixedrate(timertaskb, 0, 1000);
    }
    private void stopb() {
        if (timerb != null) {
            timerb.cancel();
            timerb = null;
        }
    }
 
    // === 方案 c：scheduledexecutorservice ===
    private void startc() {
        schedulerc = executors.newsinglethreadscheduledexecutor();
        futurec = schedulerc.scheduleatfixedrate(() -> {
            runonuithread(this::updatetime);
        }, 0, 1, timeunit.seconds);
    }
    private void stopc() {
        if (futurec != null) futurec.cancel(true);
        if (schedulerc != null) schedulerc.shutdown();
    }
 
    // === 方案 d：rxjava interval ===
    private void startd() {
        disposabled = observable.interval(0, 1, timeunit.seconds)
            .subscribeon(schedulers.io())
            .observeon(androidschedulers.mainthread())
            .subscribe(x -> updatetime());
    }
    private void stopd() {
        if (disposabled != null && !disposabled.isdisposed()) {
            disposabled.dispose();
        }
    }
 
    // === 方案 e：kotlin coroutines + flow ===
    /*
    private void starte() {
        jobe = coroutinescope(dispatchers.main).launch {
            flow {
                while (true) {
                    emit(unit)
                    delay(1000)
                }
            }.collect {
                updatetime()
            }
        };
    }
    private void stope() {
        if (jobe != null && jobe.isactive()) {
            jobe.cancel();
        }
    }
    */
 
    @override protected void ondestroy() {
        super.ondestroy();
        // 确保停止所有方案
        stopa(); stopb(); stopc(); stopd(); stope();
    }
}
 
/*
=========================== res/layout/activity_main.xml ===========================
<?xml version="1.0" encoding="utf-8"?>
<linearlayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:gravity="center"
    android:padding="24dp"
    android:layout_width="match_parent" android:layout_height="match_parent">
    <textview
        android:id="@+id/tvclock"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="--:--:--"
        android:textsize="48sp"
        android:textstyle="bold"/>
    <linearlayout
        android:orientation="horizontal"
        android:layout_margintop="32dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">
        <button
            android:id="@+id/btnstart"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="开始刷新"/>
        <button
            android:id="@+id/btnstop"
            android:layout_marginstart="16dp"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="停止刷新"/>
    </linearlayout>
</linearlayout>
=========================== 布局结束 ===========================
*/
 
/*
=========================== app/build.gradle 关键依赖 ===========================
dependencies {
    implementation 'androidx.appcompat:appcompat:1.5.1'
    implementation 'io.reactivex.rxjava3:rxjava:3.1.5'
    implementation 'io.reactivex.rxjava3:rxandroid:3.0.0'
    // kotlin coroutines & flow（如需要示例 e）
    // implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-core:1.6.4'
    // implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.6.4'
}
=========================== gradle 结束 ===========================
*/