java - 如何在我的主要活动中声明一个新的 Java 类？

Question

我正在尝试创建一个涉及拖放功能的纸牌游戏。有没有一种方法可以在我的主要活动中使用拖放功能，而无需启动将其声明为 MainActivity 的函数？它给了我一个错误。

这是我的 MainActivity 代码：

package com.techietoystore.newsnakes;

import androidx.appcompat.app.AppCompatActivity;

import android.app.Application;
import android.content.DialogInterface;
import android.media.Image;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.ImageView;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import android.content.ClipData;
import android.content.ClipDescription;
import android.graphics.Color;
import android.graphics.PorterDuff;
import android.os.Bundle;
import android.util.Log;
import android.view.DragEvent;
import android.view.View;
import android.view.ViewGroup;
//import android.widget.Button;
import android.widget.ImageView;
import android.widget.LinearLayout;
//import android.widget.TextView;
//import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;


public class MainActivity extends AppCompatActivity {
    ImageView iv_1, iv_2, iv_3, iv_4, iv_5, iv_6, iv_7, iv_8;


    private Button button;
    private iv_1 imageView1;

    ArrayList<Integer> cards;

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

        iv_1 = (ImageView) findViewById(R.id.imageView1);
        iv_2 = (ImageView) findViewById(R.id.imageView2);
        iv_3 = (ImageView) findViewById(R.id.imageView3);
        iv_4 = (ImageView) findViewById(R.id.imageView4);
        iv_5 = (ImageView) findViewById(R.id.imageView5);
        iv_6 = (ImageView) findViewById(R.id.imageView6);
        iv_7 = (ImageView) findViewById(R.id.imageView7);
        iv_8 = (ImageView) findViewById(R.id.imageView8);


        iv_1.setVisibility(View.INVISIBLE);
        iv_2.setVisibility(View.INVISIBLE);
        iv_3.setVisibility(View.INVISIBLE);
        iv_4.setVisibility(View.INVISIBLE);
        iv_5.setVisibility(View.INVISIBLE);
        iv_6.setVisibility(View.INVISIBLE);
        iv_7.setVisibility(View.INVISIBLE);
        iv_8.setVisibility(View.INVISIBLE);

        cards = new ArrayList<>();

        cards.add(109);
        cards.add(110);
        cards.add(111);
        cards.add(112);
        cards.add(113);
        cards.add(114);
        cards.add(115);
        cards.add(116);

        button = (Button) findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Collections.shuffle(cards);

                //sort hands
                List<Integer> player1Cards = new ArrayList<>();
                for (int i = 0; i < 4; i++) {
                    player1Cards.add(cards.get(i));

                    Collections.sort(player1Cards);
                }
                List<Integer> player2Cards = new ArrayList<>();
                for (int i = 4; i < 8; i++) {
                    player2Cards.add(cards.get(i));

                    Collections.sort(player2Cards);
                }



                //deal
                assignImages(player1Cards.get(0), iv_1);
                assignImages(player1Cards.get(1), iv_2);
                assignImages(player1Cards.get(2), iv_3);
                assignImages(player1Cards.get(3), iv_4);
                assignImages(player2Cards.get(0), iv_5);
                assignImages(player2Cards.get(1), iv_6);
                assignImages(player2Cards.get(2), iv_7);
                assignImages(player2Cards.get(3), iv_8);


                iv_1.setVisibility(View.VISIBLE);
                iv_2.setVisibility(View.VISIBLE);
                iv_3.setVisibility(View.VISIBLE);
                iv_4.setVisibility(View.VISIBLE);
                iv_5.setVisibility(View.VISIBLE);
                iv_6.setVisibility(View.VISIBLE);
                iv_7.setVisibility(View.VISIBLE);
                iv_8.setVisibility(View.VISIBLE);

            }

            public void assignImages(int card, ImageView image) {
                switch (card) {
                    case 109:
                        image.setImageResource(R.drawable.r13);
                        break;
                    case 110:
                        image.setImageResource(R.drawable.r14);
                        break;
                    case 111:
                        image.setImageResource(R.drawable.r15);
                        break;
                    case 112:
                        image.setImageResource(R.drawable.y11);
                        break;
                    case 113:
                        image.setImageResource(R.drawable.y12);
                        break;
                    case 114:
                        image.setImageResource(R.drawable.y13);
                        break;
                    case 115:
                        image.setImageResource(R.drawable.y14);
                        break;
                    case 116:
                        image.setImageResource(R.drawable.y15);
                        break;

                }


            }

        });
    }
    //play card


    private class iv_1 {
    }
}

这是拖放的代码：

import android.content.ClipData;
import android.content.ClipDescription;
import android.graphics.Color;
import android.graphics.PorterDuff;
import android.os.Bundle;
import android.view.DragEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.LinearLayout;

import androidx.appcompat.app.AppCompatActivity;

import com.techietoystore.newsnakes.R;

public class dragFunction {
    public class MainActivity extends AppCompatActivity implements View.OnDragListener, View.OnLongClickListener {
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            //Find all views and set Tag to all draggable views
            ImageView imgVw = (ImageView) findViewById(R.id.imageView1);
            imgVw.setTag("ANDROID ICON");
            imgVw.setOnLongClickListener(this);
            //Set Drag Event Listeners for defined layouts
//        findViewById(R.id.layout1).setOnDragListener(this);
            findViewById(R.id.layout2).setOnDragListener(this);
//        findViewById(R.id.layout3).setOnDragListener(this);
        }
        @Override
        public boolean onLongClick(View v) {
            // Create a new ClipData.Item from the ImageView object's tag
            ClipData.Item item = new ClipData.Item((CharSequence) v.getTag());
            // Create a new ClipData using the tag as a label, the plain text MIME type, and
            // the already-created item. This will create a new ClipDescription object within the
            // ClipData, and set its MIME type entry to "text/plain"
            String[] mimeTypes = {ClipDescription.MIMETYPE_TEXT_PLAIN};
            ClipData data = new ClipData(v.getTag().toString(), mimeTypes, item);
            // Instantiates the drag shadow builder.
            View.DragShadowBuilder dragshadow = new View.DragShadowBuilder(v);
            // Starts the drag
            v.startDrag(data        // data to be dragged
                    , dragshadow   // drag shadow builder
                    , v           // local data about the drag and drop operation
                    , 0          // flags (not currently used, set to 0)
            );
            return true;
        }
        // This is the method that the system calls when it dispatches a drag event to the listener.
        @Override
        public boolean onDrag(View v, DragEvent event) {
            // Defines a variable to store the action type for the incoming event
            int action = event.getAction();
            // Handles each of the expected events
            switch (action) {

                case DragEvent.ACTION_DRAG_STARTED:
                    // Determines if this View can accept the dragged data
                    if (event.getClipDescription().hasMimeType(ClipDescription.MIMETYPE_TEXT_PLAIN)) {
                        // if you want to apply color when drag started to your view you can uncomment below lines
                        // to give any color tint to the View to indicate that it can accept data.
                        // v.getBackground().setColorFilter(Color.BLUE, PorterDuff.Mode.SRC_IN);
                        // Invalidate the view to force a redraw in the new tint
                        //  v.invalidate();
                        // returns true to indicate that the View can accept the dragged data.
                        return true;
                    }
                    // Returns false. During the current drag and drop operation, this View will
                    // not receive events again until ACTION_DRAG_ENDED is sent.
                    return false;

                case DragEvent.ACTION_DRAG_ENTERED:
                    // Applies a GRAY or any color tint to the View. Return true; the return value is ignored.
                    v.getBackground().setColorFilter(Color.GRAY, PorterDuff.Mode.SRC_IN);
                    // Invalidate the view to force a redraw in the new tint
                    v.invalidate();
                    return true;

                case DragEvent.ACTION_DRAG_LOCATION:
                    // Ignore the event
                    return true;

                case DragEvent.ACTION_DRAG_EXITED:
                    // Re-sets the color tint to blue. Returns true; the return value is ignored.
                    // view.getBackground().setColorFilter(Color.BLUE, PorterDuff.Mode.SRC_IN);
                    //It will clear a color filter .
                    v.getBackground().clearColorFilter();
                    // Invalidate the view to force a redraw in the new tint
                    v.invalidate();
                    return true;

                case DragEvent.ACTION_DROP:
                    // Gets the item containing the dragged data
                    ClipData.Item item = event.getClipData().getItemAt(0);
                    // Gets the text data from the item.
                    String dragData = item.getText().toString();
                    // Displays a message containing the dragged data.
                    //Toast.makeText(this, "Dragged data is " + dragData, Toast.LENGTH_SHORT).show();
                    // Turns off any color tints
                    v.getBackground().clearColorFilter();
                    // Invalidates the view to force a redraw
                    v.invalidate();

                    View vw = (View) event.getLocalState();
                    ViewGroup owner = (ViewGroup) vw.getParent();
                    owner.removeView(vw); //remove the dragged view
                    //caste the view into LinearLayout as our drag acceptable layout is LinearLayout
                    LinearLayout container = (LinearLayout) v;
                    container.addView(vw);//Add the dragged view
                    vw.setVisibility(View.VISIBLE);//finally set Visibility to VISIBLE
                    // Returns true. DragEvent.getResult() will return true.
                    return true;

                case DragEvent.ACTION_DRAG_ENDED:
                    // Turns off any color tinting
                    v.getBackground().clearColorFilter();
                    // Invalidates the view to force a redraw
                    v.invalidate();
                    // Does a getResult(), and displays what happened.

                    // An unknown action type was received.
//            default:
//                Log.e("DragDrop Example", "Unknown action type received by OnDragListener.");
//               break;
            }
            return false;
        }
    }

}

我还为拖放功能声明了一个新类。我是否也可以在 MainActivity 代码中调用拖放类？

标签： javaandroid