Question

我是一名新开发人员，我尝试在我的项目上使用适配器，Android应用程序意外停止，未显示任何错误。尝试使用网格视图，图像视图和微调器，但不幸的是，在所有情况下，我的应用程序都停止运行而未显示任何错误在这里，我尝试了使用自定义适配器的微调器在一个类中尝试过阵列适配器，它可以运行，但是我需要一个单独的适配器类，并由另一个类调用它

MainActivity

 package com.safaa.user.last_app;

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

public class MainActivity extends AppCompatActivity {
String [] fruit={
        "apple","panana","orange"
};
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Spinner spinner=findViewById(R.id.spinner);
        CustomSpinnerAdapter spinnerAdapter=new CustomSpinnerAdapter(this,fruit);
        spinner.setAdapter(spinnerAdapter);
        spinner.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int i, long id) {

                Toast.makeText(MainActivity.this,fruit[i],Toast.LENGTH_SHORT).show();
            }

            public void onNothingSelected(AdapterView<?>adapterView){

            }
        });
    }
}

Main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <android.support.v7.widget.AppCompatSpinner
        android:layout_width="200dp"
        android:layout_height="50dp"
        android:id="@+id/spinner"
        android:layout_centerHorizontal="true">

    </android.support.v7.widget.AppCompatSpinner>
</RelativeLayout>

CustomSpinnerAdapter

package com.safaa.user.last_app;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

import java.util.zip.Inflater;

import static com.safaa.user.last_app.R.layout.spinner_row;

public class CustomSpinnerAdapter extends BaseAdapter {
    Activity activity;
    String []fruit;
    LayoutInflater inflater;

@SuppressLint("ServiceCast")
public CustomSpinnerAdapter (Activity activity, String [] fruit){
this.activity=activity;
this.fruit=fruit;
    inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);


    }

    @Override
    public int getCount() {
        return fruit.length;
    }

    @Override
    public Object getItem(int position) {
        return null;
    }

    @Override
    public long getItemId(int position) {
        return 0;
    }

    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {
View row      = inflater.inflate(R.layout.spinner_row,null);

        TextView textView=(TextView)row.findViewById(R.id.txt1);
        textView.setText(fruit[i]);
        return row;
    }
}

spinner_row.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="40dp">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/txt1"
        android:layout_marginLeft="10dp"
        />


</LinearLayout>

Answer 1

您需要更新这两种方法：

@Override
public String getItem(int position) {
    return fruit[position];
}

@Override
public long getItemId(int position) {
    return position;
}

还需要将ItemSelectedListener与Spinner一起使用，而不要ItemClickListener更改为以下代码：

spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
                Toast.makeText(MainActivity.this,fruit[i],Toast.LENGTH_SHORT).show();
            }

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

            }
        });

适配器无法激活

1 个答案: