java - android studio 中旋转器的确切数据类型是什么？

Question

我想在 Android Studio 中编写一个抵押贷款计算器应用程序。我使用旋转器来选择抵押贷款的长度。我想使用所选项目的值进行一些计算。我想做一个语句来将所选项目的值与字符串变量进行比较，但 if 语句未启动。我应该将所选项目的类型转换为字符串吗？

///adapter for the payment frequency
ArrayAdapter<CharSequence> adapter2 = ArrayAdapter.createFromResource(this,
           R.array.paymentFrequency, android.R.layout.simple_spinner_item); //payment frequency is the name of the string in string.xml
// Specify the layout to use when the list of choices appears
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
// Apply the adapter to the spinner
frequency.setAdapter(adapter2);

frequency.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
          @Override
          public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
              paymentFrequency = String.valueOf(frequency.getSelectedItem());
              Toast.makeText(Main2Activity.this, "choosen year:" + paymentFrequency, Toast.LENGTH_SHORT).show();
           }

          @Override
          public void onNothingSelected(AdapterView<?> parent) {
              Toast.makeText(Main2Activity.this, "nothing selected",Toast.LENGTH_SHORT).show();
          }
});


public void calculate(View v){

        if (paymentFrequency == "by-weekly"){
            //the number of payment will be multiply by 24
            n = Integer.parseInt(amortizasionPeriod)*24;
            Toast.makeText(Main2Activity.this, "Number of payment:" + n, Toast.LENGTH_SHORT).show();
        }
        else if ( paymentFrequency == "monthly"){
            //the number of payment will be multiply by 12
            n = Integer.parseInt(amortizasionPeriod)*12;
            Toast.makeText(Main2Activity.this, "Number of payment:" + n, Toast.LENGTH_SHORT).show();
        }
        else {
            Toast.makeText(Main2Activity.this, "Error", Toast.LENGTH_SHORT).show();
        }
}

Answer 1

在 Java 中查看两个字符串是否相等时，您需要使用 Java 中的 String.equals(String) 方法(请参阅: https://docs.oracle.com/javase/7/docs/api/java/lang/String.html#equals(java.lang.Object) )。因此，您应该拥有以下代码，而不是您拥有的代码:

if (paymentFrequency.equals("by-weekly")) {
    //the number of payment will be multiply by 24
    n = Integer.parseInt(amortizasionPeriod) * 24;
    Toast.makeText(Main2Activity.this, "Number of payment:" + n, Toast.LENGTH_SHORT).show();
} else if (paymentFrequency.equals("monthly")) {
    //the number of payment will be multiply by 12
    n = Integer.parseInt(amortizasionPeriod) * 12;
    Toast.makeText(Main2Activity.this, "Number of payment:" + n, Toast.LENGTH_SHORT).show();
} else {
    Toast.makeText(Main2Activity.this, "Error", Toast.LENGTH_SHORT).show();
}