package com.example.testapplication;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
/**
* 使用Handler的小DEMO
1. 手动增加/减少
2. 自动增加/减少
3. 限制数字的最大和最小值 [1,20]
4. 限制Button可操作性
*/
public class HandlerDemoActivity extends ApplicationActivity implements View.OnClickListener {
private static final int WHAT_INCREASE = 1;
private static final int WHAT_DECREASE = 2;
private TextView tv_demo_number;
private Button btn_demo_increase;
private Button btn_demo_decrease;
private Button btn_demo_pause;
// 创建handler线程
private Handler handler = new Handler(){
@Override
public void handleMessage(@NonNull Message msg) {
super.handleMessage(msg);
// 得到当前显示的数值
int number = Integer.parseInt(tv_demo_number.getText().toString());
switch (msg.what){
case WHAT_INCREASE:
// 限制number <= 20
if(number == 20){
// 设置暂停不能操作
btn_demo_pause.setEnabled(false);
Toast.makeText(HandlerDemoActivity.this, "已经达到最大值", Toast.LENGTH_SHORT).show();
return;
}
number++;
tv_demo_number.setText(number +"");
// 发送增加的延迟消息
handler.sendEmptyMessageDelayed(WHAT_INCREASE,1000);
break;
case WHAT_DECREASE:
// 限制number>=1
if(number ==1){
// 设置暂停不能操作
btn_demo_pause.setEnabled(false);
Toast.makeText(HandlerDemoActivity.this, "已经是最小值", Toast.LENGTH_SHORT).show();
return;
}
number--;
tv_demo_number.setText(number+"");
// 发送减少的延迟消息
handler.sendEmptyMessageDelayed(WHAT_DECREASE,1000);
break;
default:
break;
}
}
};
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_handler6);
init();
}
private void init() {
tv_demo_number = (TextView) findViewById(R.id.tv_demo_number);
btn_demo_increase = (Button) findViewById(R.id.btn_demo_increase);
btn_demo_decrease = (Button) findViewById(R.id.btn_demo_decrease);
btn_demo_pause = (Button) findViewById(R.id.btn_demo_pause);
btn_demo_increase.setOnClickListener(this);
btn_demo_decrease.setOnClickListener(this);
btn_demo_pause.setOnClickListener(this);
}
@Override
public void onClick(View view) {
if(view== btn_demo_increase){ //自动增加 what =1
// 限制Button可操作性
btn_demo_increase.setEnabled(false);
btn_demo_decrease.setEnabled(true);
btn_demo_pause.setEnabled(true);
// 停止减少(移除未处理的减少的消息)
handler.removeMessages(WHAT_DECREASE);
// 发消息(增加)
handler.sendEmptyMessage(WHAT_INCREASE);
}else if(view==btn_demo_decrease) {//自动减少 what=2
//限制Button可操作性
btn_demo_increase.setEnabled(true);
btn_demo_decrease.setEnabled(false);
btn_demo_pause.setEnabled(true);
//停止增加(移除未处理的增加的消息)
handler.removeMessages(WHAT_INCREASE);
//发消息(减少)
handler.sendEmptyMessage(WHAT_DECREASE);
}else if(view==btn_demo_pause) {//暂停
//限制Button可操作性
btn_demo_increase.setEnabled(true);
btn_demo_decrease.setEnabled(true);
btn_demo_pause.setEnabled(false);
//停止增加/减少(移除未处理的减少/增加的消息)
handler.removeMessages(WHAT_INCREASE);
handler.removeMessages(WHAT_DECREASE);
}
}
}
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="@+id/tv_demo_number"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:text="10"
android:textColor="#ff0000"
android:textSize="20sp"/>
<Button
android:id="@+id/btn_demo_increase"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="自动增加" />
<Button
android:id="@+id/btn_demo_decrease"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="自动减少" />
<Button
android:id="@+id/btn_demo_pause"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="暂停"
android:enabled="false"/>
</LinearLayout>