如何在Activity中使用Spinner设置控件的下拉框

重点：Spinner

首先在Strings.xml中添加下拉框选项内容

贴代码：

<resources>
    <string name="app_name">First</string>
    <string-array name="inArray">
        <item>1</item>
        <item>2</item>
        <item>3</item>
    </string-array>

</resources>

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其次我们需要在布局中引入选项卡

贴代码：

<Spinner
    android:id="@+id/inArray"
    android:layout_width="85dp"
    android:layout_height="30dp"
    android:gravity="center|right"
    android:layout_marginLeft="5dp"
    android:background="@drawable/whitesmoke"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintTop_toTopOf="parent"/>

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最后写Java代码

贴代码：

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        DensityUtils.setDensity(getApplication(),this);
        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
        setContentView(R.layout.activity_main);

Spinner spinner=findViewById(R.id.inArray);
        ArrayAdapter<CharSequence> adapter=ArrayAdapter.createFromResource(getApplicationContext(),R.array.inArray, android.R.layout.simple_spinner_item);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner.setAdapter(adapter);

        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                Toast.makeText(MainActivity.this,"position:"+position,Toast.LENGTH_SHORT).show();
            }

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

            }
        });

    }

}

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自此就结束了。