常用控件

public class MainActivity extends ActionBarActivity {


    private Button btn = null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btn = (Button) this.findViewById(R.id.btnChoose);
        btn.setOnClickListener(new View.OnClickListener() {  // 定义了一个按钮，然后点显示日期组件
            @Override
            public void onClick(View v) {
                new DatePickerDialog(MainActivity.this, new DatePickerDialog.OnDateSetListener() {
                    @Override
                    public void onDateSet(DatePicker view, int year, int month, int dayOfMonth) {  // 当日期选择的时候
                        String date = String.format("%d-%d-%d", year, month, dayOfMonth);
                        btn.setText(date);       // 改变按钮的text
                        System.out.print(date);  // 打印
                    }
                }, 2016, 1, 1).show();
            }
        });

        System.out.println("onCreate");
    }


}

public class MainActivity extends ActionBarActivity {


    private Button btn = null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btn = (Button) this.findViewById(R.id.btnChoose);
        btn.setOnClickListener(new View.OnClickListener() {  // 定义了一个按钮，然后点显示时间控件
            @Override
            public void onClick(View v) {
                // 创建一个时间控件
               new TimePickerDialog(MainActivity.this, new TimePickerDialog.OnTimeSetListener() {
                   @Override
                   public void onTimeSet(TimePicker view, int hourOfDay, int minute) {  // 选择时间市，相应
                       String s = String.format("%d:%d", hourOfDay, minute);
                       btn.setText(s);
                   }
               }, 0, 0, true).show();
            }
        });

        System.out.println("onCreate");
    }
    
}

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

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="世界上最大的洋?"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:id="@+id/textView2" />


    <!-- 单选组，单选按钮必须要放一个RadioGroup -->
    <RadioGroup
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">


        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="A.大西洋"
            android:id="@+id/rbA" />

        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="B.太平洋"
            android:id="@+id/rbB" />

        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="C.印度洋"
            android:id="@+id/rbC" />



    </RadioGroup>

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="提交"
        android:id="@+id/btnChoose" />


</LinearLayout>

public class MainActivity extends ActionBarActivity {


    private Button btn = null;
    private RadioButton rbA = null;   // 单选按钮A
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btn = (Button) this.findViewById(R.id.btnChoose);
        rbA = (RadioButton) this.findViewById(R.id.rbA);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(rbA.isChecked()) {   // 当选择是正确的
                    // 提示
                    Toast.makeText(MainActivity.this, "所选是正确的", Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(MainActivity.this, "所选是错误的", Toast.LENGTH_SHORT).show();
                }
            }
        });

        System.out.println("onCreate");
    }

}