Question

我试图让一个微调器（2）从另一个微调器（1）中改变它的内容。

我目前在第二个微调器的数组适配器中出现错误 “错误：（28,57）错误：无法推断ArrayAdapter的类型参数＆lt;＆gt;”

这是我的代码：

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Spinner;

public class DetailsForm extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.details_form);

        final Spinner carBrand = (Spinner) findViewById(R.id.carBrand);
        String[] items = new String[]{"Honda", "Nissan", "Toyota"};
        ArrayAdapter<String> adapter = new ArrayAdapter<>(this, android.R.layout.simple_spinner_dropdown_item, items);
        carBrand.setAdapter(adapter);
        carBrand.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id){
            String carBrand = parent.getSelectedItem().toString();
                if (carBrand.equals("Nissan")) {
                    final Spinner model = (Spinner) findViewById(R.id.model);
                    String[] models = new String[]{"S14", "R34", "240SX"};
                    ArrayAdapter<String> modeladapter = new ArrayAdapter<>(this, android.R.layout.simple_spinner_dropdown_item, models);
                    model.setAdapter(modeladapter);

                } else if (carBrand.equals("Honda")) {
                    Spinner model = (Spinner) findViewById(R.id.model);
                    String[] models = new String[]{"Civic", "NSX", "Accord"};
                    ArrayAdapter<String> modeladapter = new ArrayAdapter<>(this, android.R.layout.simple_spinner_dropdown_item, models);
                    model.setAdapter(modeladapter);
                } else if (carBrand.equals("Toyota")) {
                    Spinner model = (Spinner) findViewById(R.id.model);
                    String[] models = new String[]{"Supra", "AE86", "GT86"};
                    ArrayAdapter<String> modeladapter = new ArrayAdapter<>(this, android.R.layout.simple_spinner_dropdown_item, models);
                    model.setAdapter(modeladapter);
                }
            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {

            }
        });

非常感谢任何帮助。

Answer 1

更改您的代码

发件人：

@Override public void onItemSelected(AdapterView<?> parent, View view, int position, long id){ String carBrand = parent.getSelectedItem().toString(); if (carBrand.equals("Nissan")) { final Spinner model = (Spinner) findViewById(R.id.model); String[] models = new String[]{"S14", "R34", "240SX"}; ArrayAdapter<String> modeladapter = new ArrayAdapter<>(this, android.R.layout.simple_spinner_dropdown_item, models); model.setAdapter(modeladapter); } else if (carBrand.equals("Honda")) { Spinner model = (Spinner) findViewById(R.id.model); String[] models = new String[]{"Civic", "NSX", "Accord"}; ArrayAdapter<String> modeladapter = new ArrayAdapter<>(this, android.R.layout.simple_spinner_dropdown_item, models); model.setAdapter(modeladapter); } else if (carBrand.equals("Toyota")) { Spinner model = (Spinner) findViewById(R.id.model); String[] models = new String[]{"Supra", "AE86", "GT86"}; ArrayAdapter<String> modeladapter = new ArrayAdapter<>(this, android.R.layout.simple_spinner_dropdown_item, models); model.setAdapter(modeladapter); } }

要

@Override public void onItemSelected(AdapterView<?> parent, View view, int position, long id){ String carBrand = parent.getSelectedItem().toString(); if (carBrand.equals("Nissan")) { final Spinner model = (Spinner) findViewById(R.id.model); String[] models = new String[]{"S14", "R34", "240SX"}; ArrayAdapter<String> modeladapter = new ArrayAdapter<>(YourActivity.this, android.R.layout.simple_spinner_dropdown_item, models); model.setAdapter(modeladapter); } else if (carBrand.equals("Honda")) { Spinner model = (Spinner) findViewById(R.id.model); String[] models = new String[]{"Civic", "NSX", "Accord"}; ArrayAdapter<String> modeladapter = new ArrayAdapter<>(YourActivity.this, android.R.layout.simple_spinner_dropdown_item, models); model.setAdapter(modeladapter); } else if (carBrand.equals("Toyota")) { Spinner model = (Spinner) findViewById(R.id.model); String[] models = new String[]{"Supra", "AE86", "GT86"}; ArrayAdapter<String> modeladapter = new ArrayAdapter<>(YourActivity.this, android.R.layout.simple_spinner_dropdown_item, models); model.setAdapter(modeladapter); } }

YourActivity是您的activity班级名称。此更改是必要的，因为在OnItemSelectedListener，this内表示与context类型不同的侦听器对象，您需要context或activity的对象引用调用ArrayAdapter构造函数。这个解决方案应该适合你。

Answer 2

您必须传递当前活动的上下文。在此行中将this更改为DetailsForm.this:

ArrayAdapter<String> modeladapter = new ArrayAdapter<>(DetailsForm.this, android.R.layout.simple_spinner_dropdown_item, models);

Java - 通过微调器更改微调器的值

2 个答案: