Question

我想了解如何在另一个类中调用一个类的非静态方法。

我见过以下内容：

Class1 c1 = new Class1();
c1.doSomething();

在另一个类中调用方法Class1时。

public class AddA extends AppCompatActivity {
@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_add_a);
        final DatePicker datePicker = (DatePicker) this.findViewById(R.id.DatePicker);
        final TimePicker timePicker = (TimePicker) this.findViewById(R.id.TimePicker);

 Button clear = (Button) this.findViewById(R.id.clear);
        clear.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                subject.setText("");
                message.setText("");
                //DatePicker.setCurrentDateOnView();
                //TimePicker.setCurrentTimeOnView();
                DateTimePicker datePicker = new DateTimePicker();
                datePicker.setCurrentDateOnView(); //null here
            }

        });
//...More code
}

public class DateTimePicker extends AddA {
      @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_add_alerts);

            setCurrentDateOnView();
            setCurrentTimeOnView();
        }

        // display current date
        public void setCurrentDateOnView() { //null here


            final Calendar c = Calendar.getInstance();
            year = c.get(Calendar.YEAR);
            month = c.get(Calendar.MONTH);
            day = c.get(Calendar.DAY_OF_MONTH);

            // set current date into datepicker
            dpResult.init(year, month, day, null);

        }
    ///..More code}

我非常感谢详细解释。是的，我研究了这个概念，但我无法理解。谢谢！

Answer 1

根本不需要类继承来解决问题中的问题。

我能够将这个工作示例放在一起，将两个选择器重置为当前日期。

<强> MainActivity

public class MainActivity extends Activity {

    private Button resetButton;
    private DatePicker datePicker;
    private TimePicker timePicker;

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

        resetButton = (Button) findViewById(R.id.btn_reset);
        datePicker = (DatePicker) findViewById(R.id.datePicker);
        timePicker = (TimePicker) findViewById(R.id.timePicker);

        resetButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Calendar c = Calendar.getInstance();

                int year = c.get(Calendar.YEAR);
                int month = c.get(Calendar.MONTH);
                int day = c.get(Calendar.DAY_OF_MONTH);

                datePicker.init(year, month, day, null);

                int hour = c.get(Calendar.HOUR_OF_DAY);
                int minute = c.get(Calendar.MINUTE);

                timePicker.setCurrentHour(hour);
                timePicker.setCurrentMinute(minute);
            }
        });

    }
}

<强> activity_main.xml中

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:orientation="vertical">

    <Button
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Reset"
            android:id="@+id/btn_reset"/>
    <DatePicker
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/datePicker" 
            android:layout_gravity="center_horizontal"/>
    <TimePicker
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center_horizontal"
            android:id="@+id/timePicker"/>
</LinearLayout>

或者，如果您想要方法来设置日期和时间，您可以这样做

resetButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Calendar c = Calendar.getInstance();
                setDate(c);
                setTime(c);
            }
        });


} // end onCreate

private void setDate(Calendar c) {
    int year = c.get(Calendar.YEAR);
    int month = c.get(Calendar.MONTH);
    int day = c.get(Calendar.DAY_OF_MONTH);

    datePicker.init(year, month, day, null);
}

private void setTime(Calendar c) {
    int hour = c.get(Calendar.HOUR_OF_DAY);
    int minute = c.get(Calendar.MINUTE);

    timePicker.setCurrentHour(hour);
    timePicker.setCurrentMinute(minute);
}

如何调用另一个类的非静态方法

1 个答案: