java - 单击时如何从微调器下拉列表中创建第二个 Activity ？

Question

//MainActivity Details

package com.yay_or_nay.www.yayornayv1;
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;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
Spinner spinner = (Spinner) findViewById(R.id.spinner);

// Create an ArrayAdapter using the string array and a default spinner layout
    ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this, R.array.Categories_array, android.R.layout.simple_spinner_item);

// 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
    spinner.setAdapter(adapter);

    spinner.setOnItemSelectedListener(this);
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

    String sSelected=parent.getItemAtPosition(position).toString();
    Toast.makeText(this,sSelected, Toast.LENGTH_SHORT).show();


}

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

}

}

我正在使用的 XML 文件

<?xml version="1.0" encoding="utf-8"?>

<string-array name="Categories_array">
    <item>Technology</item>
    <item>Science</item>
    <item>Fashion</item>
    <item>Photography</item>
    <item>Cars</item>
    <item>Lifestyle</item>
    <item>Food</item>
</string-array>

例如，当我单击“技术”微调器数组按钮时，我要向主要 Activity 添加什么？那么它可以创建一个新的 Activity Action 吗？我试图做到这一点，如果用户单击微调器下拉列表中的选项，它将创建一个新实例。

`

Answer 1

package project.com.spinnerclick;

import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class MainActivity extends AppCompatActivity 

private Spinner spinner;
List<String> categoriesArray;
Context mContext;

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

private void initializeUI() {
    //initialize context;
    mContext = this;
    //initialize list to pass it spinner adapter
    categoriesArray = new ArrayList<>();
    // assign values to categories list
    categoriesArray = Arrays.asList(getResources().getStringArray(R.array.categories_array));
    // initialize spinner component
    spinner = (Spinner) findViewById(R.id.spinner);
    //set spinner adapter
    spinner.setAdapter(new ArrayAdapter<>(mContext,
            android.R.layout.simple_spinner_dropdown_item, categoriesArray));


    //setting in item select Listener to spinner items
    spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> adapterView, View view, int position, long id) {
            // you can open any activity by getting position of current
            // selected item and open the related activity to this position
            switch (position) {
                case 1:
                    startActivity(new Intent(mContext, SecondActivity.class));
                    break;
                case 2:
                    startActivity(new Intent(mContext, Main2Activity.class));
                    break;
            }
            //second solution by getting the clicked item value
            // and open activity according this value
            String selectItem = spinner.getItemAtPosition(position).toString();
            Toast.makeText(mContext, selectItem, Toast.LENGTH_SHORT).show();


        }

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

        }
    });


}
}

这是 XML 格式的微调器值

 <resources>
    <string name="app_name">SpinnerClick</string>
    <string-array name="categories_array">
        <item>select Item</item>
        <item>Technology</item>
        <item>Science</item>
        <item>Fashion</item>
        <item>Photography</item>
        <item>Cars</item>
        <item>Lifestyle</item>
        <item>Food</item>
    </string-array>
</resources>