文章目录
- 前言
- 一、效果显示
- 二、代码
-
- 主代码
- 总结
前言
开发和实现汇率转换工具。
一、效果显示
二、代码
准备工作和风格布局与我开发的另一个小工具(长度转换工具)一致。详情请参阅我的上一篇文章。 链接: Android实用小工具开发2-长度转换工具
此外，本项目还使用了调用网络接口API为了计算转换，需要实时获取货币汇率，因此需要创建呼叫网络接口API并行执行调用接口工具类，详见上一篇文章。 链接: Android开发实用小技巧五——调用网络接口API并处理返回结果（json）
主代码
ExchangeRateConversionActivity.java ：
public class ExchangeRateConversionActivity extends AppCompatActivity implements View.OnClickListener, AdapterView.OnItemSelectedListener, LoadDataAsyncTask.onGetNetDataListener {
private final static String EXCHANGE_RATE_CONVERSION_API = "https://open.er-api.com/v6/latest/"; // 定义下拉列表中需要显示的单位名称 private static final String[] nameArray = {
"人民币", "美元", "欧元", "日元", "港币", "韩元", "英镑", "泰铢", "新台币", "越南盾", "阿尔及利亚第纳尔", "阿根廷比索", "阿联酋迪拉姆", "阿曼里亚尔", "澳大利亚元", "澳门元", "白俄罗斯卢布", "巴林第纳尔", "保加利亚新列弗", "巴西雷亚尔", "冰岛克朗", "波兰兹罗提", "丹麦克朗", "俄罗斯卢布", "菲律宾比索", "哥伦比亚比索", "哥斯达黎加科朗", "加拿大元", "柬埔寨瑞尔", "埃及镑", "捷克克朗", "卡塔尔里亚尔", "克罗地亚库纳", "肯尼亚先令", "科威特第纳尔", "老挝基普",
"离岸人民币", "黎巴嫩镑", "罗马尼亚列伊", "马来西亚林吉特", "孟加拉塔卡", "缅甸元",
"摩洛哥迪拉姆", "墨西哥比索", "南非兰特", "挪威克朗", "瑞典克朗", "瑞士法郎",
"塞尔维亚第纳尔", "沙特里亚尔", "斯里兰卡卢比", "坦桑尼亚先令", "土耳其里拉", "文莱元",
"乌干达先令", "乌克兰格里夫纳", "新加坡元", "新西兰元", "匈牙利福林", "叙利亚镑",
"伊拉克第纳尔", "印度卢比", "印度尼西亚盾", "以色列新谢克尔", "约旦第纳尔", "赞比亚克瓦查",
"智利比索"
};
// 定义下拉列表需要显示的单位数组
private static final String[] unitArray = {
"CNY", "USD", "EUR", "JPY", "HKD", "KRW",
"GBP", "THB", "TWD", "VND", "DZD", "ARS",
"AED", "OMR", "AUD", "MOP", "BYN", "BHD",
"BGN", "BRL", "ISK", "PLN", "DKK", "RUB",
"PHP", "COP", "CRC", "CAD", "KHR", "EGP",
"CZK", "QAR", "HRK", "KES", "KWD", "LAK",
"CNH", "LBP", "RON", "MYR", "BDT", "MMK",
"MAD", "MXN", "ZAR", "NOK", "SEK", "CHF",
"RSD", "SAR", "LKR", "TZS", "TRY", "BND",
"UGX", "UAH", "SGD", "NZD", "HUF", "SYP",
"IQD", "INR", "IDR", "ILS", "JOD", "ZMW",
"CLP"
};
private Spinner sp_select1;
private Spinner sp_select2;
TextView tv_value1;
TextView tv_unit1;
TextView tv_value2;
TextView tv_unit2;
private List<Button> buttonList = new ArrayList<>();
ImageButton iv_del;
// 单位一
private String unit1 = "人民币";
// 单位二
private String unit2 = "美元";
// 数值一
private String value1 = "0";
// 数值二
private String value2 = "0";
private Map<String, Object> map;
private Map<String, Double> map1;
private int index = 1;
private double exchange_rate = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_value_conversion);
// 获取控件，并添加点击事件
findViewById(R.id.iv_back).setOnClickListener(this);
sp_select1 = findViewById(R.id.sp_select1);
sp_select2 = findViewById(R.id.sp_select2);
tv_value1 = findViewById(R.id.tv_value1);
tv_unit1 = findViewById(R.id.tv_unit1);
tv_value2 = findViewById(R.id.tv_value2);
tv_unit2 = findViewById(R.id.tv_unit2);
buttonList.add(findViewById(R.id.btn_0));
buttonList.add(findViewById(R.id.btn_1));
buttonList.add(findViewById(R.id.btn_2));
buttonList.add(findViewById(R.id.btn_3));
buttonList.add(findViewById(R.id.btn_4));
buttonList.add(findViewById(R.id.btn_5));
buttonList.add(findViewById(R.id.btn_6));
buttonList.add(findViewById(R.id.btn_7));
buttonList.add(findViewById(R.id.btn_8));
buttonList.add(findViewById(R.id.btn_9));
buttonList.add(findViewById(R.id.btn_pt));
buttonList.add(findViewById(R.id.btn_clr));
iv_del = findViewById(R.id.iv_del);
// 给按钮设置的点击事件
for (Button button : buttonList) {
button.setOnClickListener(this);
}
iv_del.setOnClickListener(this);
// 声明一个映射对象的列表，用于保存名称与单位配对信息
List<Map<String, Object>> list = new ArrayList<>();
// name是名称，unit是单位
for (int i = 0; i < nameArray.length; i++) {
Map<String, Object> item = new HashMap<>();
item.put("name", nameArray[i]);
item.put("unit", unitArray[i]);
list.add(item);
}
// 声明一个下拉列表的简易适配器，其中指定了名称与单位两组数据
SimpleAdapter adapter = new SimpleAdapter(this, list,
R.layout.item_value_conversion,
new String[]{
"name", "unit"},
new int[]{
R.id.tv_name, R.id.tv_unit});
sp_select1.setAdapter(adapter);
sp_select2.setAdapter(adapter);
// 设置下拉列表默认显示
sp_select1.setSelection(0);
sp_select2.setSelection(1);
// 给下拉框设置选择监听器，一旦用户选中某一项，就触发监听器的 onItemSelected 方法
sp_select1.setOnItemSelectedListener(this);
sp_select2.setOnItemSelectedListener(this);
}
@Override
public void onClick(View v) {
if (v.getId() != R.id.iv_back && value1.equals("暂未找到该货币的汇率"))
return;
if (v.getId() != R.id.iv_back && v.getId() != R.id.iv_del && v.getId() != R.id.btn_clr && value1.length() >= 20)
return;
String inputText = "";
// 如果不是删除按钮和返回按钮
if (v.getId() != R.id.iv_del && v.getId() != R.id.iv_back) {
inputText = ((TextView) v).getText().toString();
}
switch (v.getId()) {
// 点击了返回按钮
case R.id.iv_back:
finish();
break;
// 点击了清除按钮
case R.id.btn_clr:
clear();
break;
// 点击了删除按钮
case R.id.iv_del:
delete();
break;
// 点击了小数点按钮
case R.id.btn_pt:
if (value1.indexOf(".") == -1)
value1 = value1 + ".";
refreshText();
break;
// 点击了数字按钮
default:
if (value1.equals("0")) {
value1 = inputText;
} else {
value1 = value1 + inputText;
}
operation();
refreshText();
break;
}
}
// 清空并初始化
private void clear() {
value1 = "0";
if (!value2.equals("暂未找到该货币的汇率"))
value2 = "0";
refreshText();
}
// 刷新文本显示
private void refreshText() {
tv_value1.setText(value1);
tv_value2.setText(value2);
}
// 回退
private void delete() {
if (value1.length() != 0) {
value1 = value1.substring(0, value1.length() - 1);
if (value1.length() == 0)
value1 = "0";
operation();
refreshText();
}
}
// 运算
private void operation() {
if (value1.equals("暂未找到该货币的汇率") || value2.equals("暂未找到该货币的汇率"))
return;
if (unit1.equals(unit2))
value2 = value1;
else if (Double.parseDouble(value1) == 0)
value2 = "0";
else {
BigDecimal db1 = new BigDecimal(value1);
BigDecimal db2 = new BigDecimal(String.valueOf(exchange_rate));
value2 = String.valueOf(db1.multiply(db2).doubleValue());
}
}
// 选中某一项之后触发的回调方法
@SuppressLint("ResourceAsColor")
@Override
public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
TextView tv_unit = adapterView.findViewById(R.id.tv_unit);
tv_unit.setVisibility(GridView.GONE);
if (adapterView.getId() == R.id.sp_select1) {
tv_unit1.setText(unitArray[i]);
unit1 = nameArray[i];
// 调用接口api，获取该货币的汇率
LoadDataAsyncTask task = new LoadDataAsyncTask(this, this, false);
task.execute(EXCHANGE_RATE_CONVERSION_API + unitArray[i]);
operation();
refreshText();
} else {
tv_unit2.setText(unitArray[i]);
unit2 = nameArray[i];
index = i;
if (map1 != null) {
try {
exchange_rate = map1.get(unitArray[i]);
value2 = "0";
operation();
} catch (Exception e) {
e.printStackTrace();
value2 = "暂未找到该货币的汇率";
}
}
refreshText();
}
}
// 什么也没选执行的回调方法
@Override
public void onNothingSelected(AdapterView<?> adapterView) {
}
// 成功调用网络接口，处理返回结果
@Override
public void onSucess(String json) {
map = new Gson().fromJson(json, Map.class);
if (map != null) {
if (map.get("result").equals("success")) {
if (value1.equals("暂未找到该货币的汇率") || value2.equals("暂未找到该货币的汇率"))
value1 = "0";
map1 = (Map<String, Double>) map.get("rates");
try {
exchange_rate = map1.get(unitArray[index]);
value2 = "0";
operation();
} catch (Exception e) {
e.printStackTrace();
value2 = "暂未找到该货币的汇率";
}
refreshText();
return;
}
}
map1 = null;
value1 = "暂未找到该货币的汇率";
refreshText();
}
}
总结
以上就是汇率转换工具的开发与实现的内容。