android利用handler实现倒计时功能

2023-07-10 20:15:04 255

packagecom.tcy.handlertest; importandroidx.annotation.NonNull; importandroidx.appcompat.app.AppCompatActivity; importandroid.os.Bundle; importandroid.os.Handler; importandroid.os.Message; importandroid.widget.TextView; importjava.lang.ref.WeakReference; publicclassMainActivityextendsAppCompatActivity{ /** *倒计时标记handlercode */ publicstaticfinalintCOUNT_DOWN_CODE=10001; /** *倒计时最大值 */ publicstaticfinalintMAX_COUNT=10; /** *倒计时间隔 */ publicstaticfinalintDELAY_MILLIS=1000; TextViewtextView; @Override protectedvoidonCreate(BundlesavedInstanceState){ super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); textView=findViewById(R.id.text); CountdownTimeHandlerhandler=newCountdownTimeHandler(this); Messagemessage=Message.obtain(); message.what=COUNT_DOWN_CODE; message.arg1=MAX_COUNT; handler.sendMessageDelayed(message,DELAY_MILLIS); } publicstaticclassCountdownTimeHandlerextendsHandler{ //弱引用加在上下文上面 finalWeakReferenceweakReference; //这个方法要改一下，这样就能直接传进来上下文 publicCountdownTimeHandler(MainActivityactivity){ this.weakReference=newWeakReference<>(activity); } @Override publicvoidhandleMessage(@NonNullMessagemsg){ super.handleMessage(msg); //得到上下文 MainActivityactivity=weakReference.get(); switch(msg.what){ caseCOUNT_DOWN_CODE: intvalue=msg.arg1; activity.textView.setText(String.valueOf(value--)); if(value>=0){ //再把value发出去 Messagemessage=Message.obtain(); message.what=COUNT_DOWN_CODE; message.arg1=value; sendMessageDelayed(message,DELAY_MILLIS); } break; } } } }

android利用handler实现倒计时功能

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