Spinner与Adapter

Francis学习笔记四

              --------------------------------Spinner与Adapter

1.下拉选择控件Spinner;

2.事件监听;

一、关系说明图：



二、控件spinner学习

附部分源码：

<span style="font-size:24px;">package myapplication.com.myapplication3;

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.CheckBox;
import android.widget.CompoundButton;
import android.widget.RadioGroup;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
String[] cities = {"成都", "重庆", "武汉", "深圳"};
ArrayAdapter<String> adapter;
@Override

protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);</span>

<span style="font-size:24px;">
adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, cities);
Spinner spinner1 = (Spinner) findViewById(R.id.spinner1);
spinner1.setAdapter(adapter);

spinner1.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
<span>		</span>//方法一：如下</span>

<span style="font-size:24px;">//                if(position == 0)
//                    display("第一个被选中了");
//                else if(position == 1)
//                    display("第二个被选中了");</span>

<span style="font-size:24px;"><span>		</span>//方法二：直接显示TextView,如果上面的View对象是多个组成，则不用方法二（如下）
display(((TextView)view).getText().toString());
}

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

}
});
}

private void display(String dp) {
Toast.makeText(this, dp, Toast.LENGTH_SHORT).show();
}

}</span>

说明：

1)注意ArrayAdapter中第二个参数 resource，上面用的是android.layout.simple_spinner_item.

<span style="font-size:32px;"> ArrayAdapter(Context context, @LayoutRes int resource, @NonNull T[] objects)</span>

2)setOnItemSelectedListener(new AdapterView.OnItemSelectedListener(){

public void onItemSelected(AdapterView<?> parent, View view, int position, long id ){

}

});