Question

我正在尝试实现微调器，以便在项目选择更改时，它还会根据所选项目更改一些TextView-s。但是，当前微调器不会调用其侦听器，也不显示所选项，但它会在下拉列表中显示它们。

import android.app.ProgressDialog;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.AdapterView.OnItemSelectedListener;
import com.android.volley.Request;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest; 
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class ShowData extends AppCompatActivity implements OnItemSelectedListener {

    private TextView temp, mass, humid;
    private ArrayList<String> list;
    private Spinner spinner;
    private JSONObject jObj;
    private  JSONArray array;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate( savedInstanceState );
        setContentView( R.layout.activity_show_data );
        temp = (TextView) findViewById(R.id.temp);
        mass = (TextView) findViewById(R.id.mass);
        humid = (TextView) findViewById(R.id.humid);
        list = new ArrayList<String>();
        //fill() gets data from server and puts it into "list"
        fill();
        addItemsToSpinner();
        addListenerToSpinner();
    }

    private void addItemsToSpinner(){
        spinner = (Spinner)findViewById(R.id.date);
        ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item, list);
        dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner.setAdapter(dataAdapter);

    }

    private void  addListenerToSpinner(){
        spinner = (Spinner)findViewById(R.id.date);
        spinner.setOnItemSelectedListener(this);
    }

    private void fill() {
      //this portion works so i didnt include it 
      //gets data from the server and fills the list
    }

    public void onItemSelected(AdapterView<?> parent, View view, int pos, long id){
        Toast.makeText(getApplicationContext(), "Clicked on: " + list.get(pos), Toast.LENGTH_SHORT).show();
        temp.setText("listener works!");
        try {
            String temperature = array.getJSONObject(pos).getString("temp");
            String humidity = array.getJSONObject(pos).getString("humidity");
            String massStr = array.getJSONObject(pos).getString("mass");
            temp.setText(temperature);
            humid.setText(humidity);
            mass.setText(massStr);
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

    public void onNothingSelected(AdapterView<?> arg0) {
    }

}

XML：

[<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.lukak.pcele_mobitel.ShowData">

    <Spinner
        android:id="@+id/date"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />
        android:singleLine="true" />


    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:id="@+id/mass"
        android:layout_below="@+id/date"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginTop="26dp"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:id="@+id/temp"
        android:layout_below="@+id/mass"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginTop="36dp" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:id="@+id/humid"
        android:layout_below="@+id/temp"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginTop="36dp" />


</RelativeLayout>][1]

not showing selected item on spinner

showing available items when clicked on spinner

Answer 1

尝试这样做：

无需 addListenerToSpinner（）方法。

<强>的onCreate：

onCreate{
spinner = (Spinner)findViewById(R.id.date);
spinner.setOnItemSelectedListener(this);
}

<强> addItemsToSpinner

private void addItemsToSpinner(){
        spinner = (Spinner)findViewById(R.id.date); // ****** remove this.....
        ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item, list);
        dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner.setAdapter(dataAdapter);
}

<强> onItemSelected

public void onItemSelected{
Toast.makeText(getApplicationContext(), "Clicked on: " + list.get(pos), Toast.LENGTH_SHORT).show();
....
}

Answer 2

添加此修改后的代码。

 protected void onCreate(Bundle savedInstanceState) {
    super.onCreate( savedInstanceState );
    setContentView( R.layout.activity_show_data );
    temp = (TextView) findViewById(R.id.temp);
    mass = (TextView) findViewById(R.id.mass);
    humid = (TextView) findViewById(R.id.humid);
    spinner = (Spinner)findViewById(R.id.date);
    list = new ArrayList<String>();
    //fill() gets data from server and puts it into "list"
    fill();
    addItemsToSpinner();
    spinner.setOnItemSelectedListener(this);
}

private void addItemsToSpinner(){

    ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, list);
    dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spinner.setAdapter(dataAdapter);

}


private void fill() {
  //this portion works so i didnt include it 
  //gets data from the server and fills the list
}

public void onItemSelected(AdapterView<?> parent, View view, int pos, long id){
    Toast.makeText(getApplicationContext(), "Clicked on: " + list.get(pos), Toast.LENGTH_SHORT).show();
    temp.setText("listener works!");
    try {
        String temperature = array.getJSONObject(pos).getString("temp");
        String humidity = array.getJSONObject(pos).getString("humidity");
        String massStr = array.getJSONObject(pos).getString("mass");
        temp.setText(temperature);
        humid.setText(humidity);
        mass.setText(massStr);
    } catch (JSONException e) {
        e.printStackTrace();
    }
}

public void onNothingSelected(AdapterView<?> arg0) {
}

}

Android微调器没有调用侦听器方法

2 个答案: