Android开发：为Spinner选项赋值并用于翻译服务价格计算

Hey there! Let's walk through exactly how to tie your Spinner selections to numerical values and run that multiplication formula for your translation pricing app. This approach keeps your code organized and avoids messy string-to-value mapping later on.

1. Create a Data Model to Link Text & Values #

First, make a simple class to pair each Spinner option's display text with its corresponding numerical value. This way, you never have to guess which string maps to which number:

public class TranslationOption {
    private String optionName;
    private int optionValue;

    public TranslationOption(String name, int value) {
        this.optionName = name;
        this.optionValue = value;
    }

    // Getters for name and value
    public String getOptionName() {
        return optionName;
    }

    public int getOptionValue() {
        return optionValue;
    }

    // Override toString() so Spinner shows the name by default
    @Override
    public String toString() {
        return optionName;
    }
}

2. Populate Spinners with Your Options #

Next, initialize each Spinner with a list of TranslationOption objects, then set a custom adapter to display them. Here's how to do this in your Activity/Fragment:

// Initialize your Spinners (assuming you've linked them via findViewById)
Spinner spinner1 = findViewById(R.id.spinner1);
Spinner spinner2 = findViewById(R.id.spinner2);
Spinner spinner3 = findViewById(R.id.spinner3);
Spinner spinner4 = findViewById(R.id.spinner4);

// Create sample options for Spinner 1 (e.g., source languages)
List<TranslationOption> spinner1Options = new ArrayList<>();
spinner1Options.add(new TranslationOption("English", 2));
spinner1Options.add(new TranslationOption("Spanish", 1));
spinner1Options.add(new TranslationOption("French", 3));

// Repeat this for your other 3 Spinners with their own text/value pairs

// Set adapter for each Spinner
ArrayAdapter<TranslationOption> adapter = new ArrayAdapter<>(this, android.R.layout.simple_spinner_item, spinner1Options);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner1.setAdapter(adapter);

// Do the same for spinner2, spinner3, spinner4 with their respective option lists

3. Track Selected Values from Spinners #

Add OnItemSelectedListener to each Spinner to save the selected value whenever the user makes a choice. We'll store these values in class-level variables so we can access them later for calculation:

// Class-level variables to hold selected values
private int value1 = 1; // Default value in case no selection is made
private int value2 = 1;
private int value3 = 1;
private int value4 = 1;

// Set listener for spinner1
spinner1.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
        TranslationOption selectedOption = (TranslationOption) parent.getSelectedItem();
        value1 = selectedOption.getOptionValue();
    }

    @Override
    public void onNothingSelected(AdapterView<?> parent) {
        // Optional: Handle case where nothing is selected (set default value)
        value1 = 1;
    }
});

// Repeat this listener setup for spinner2, spinner3, spinner4, updating value2, value3, value4 respectively

4. Calculate & Display Result on Button Click #

Finally, set a click listener on your Button to multiply all selected values and show the result in your TextView:

Button calculateBtn = findViewById(R.id.calculate_button);
TextView resultTv = findViewById(R.id.result_textview);

calculateBtn.setOnClickListener(v -> {
    int totalResult = value1 * value2 * value3 * value4;
    resultTv.setText(String.format("Total Price: $%d", totalResult));
    // Adjust the string format to match your pricing display needs
});

Quick Tips to Avoid Issues #

• Always set a default value for each valueX variable (like 1) to prevent unexpected 0 results if a Spinner hasn't been interacted with yet.
• If you need decimal values (e.g., 2.5 instead of 2), change the data type to double instead of int in the TranslationOption class and your class-level variables.
• For better code reuse, you can create a helper method to set up Spinners and their listeners instead of repeating code for each one.

内容的提问来源于stack exchange，提问作者Love Programming