Question

尝试使用Android Studio生成已签名的apk时，我收到以下错误：

Error:Error: This class should provide a default constructor (a public constructor with no arguments) (com.tokom.globol.CustomGrid) [Instantiatable]

我试图通过在我的班级中使用super来解决这个问题，但它显示红线错误。

这是 CustomGrid.java

package com.tokom.globol;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;


public class CustomGrid extends BaseAdapter{
    private Context mContext;
    private final String[] web;
    private final int[] Imageid;
    public CustomGrid(Context c,String[] web,int[] Imageid ) {
        mContext = c;
        this.Imageid = Imageid;
        this.web = web;
    }
    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        return web.length;
    }
    @Override
    public Object getItem(int position) {
        // TODO Auto-generated method stub
        return null;
    }
    @Override
    public long getItemId(int position) {
        // TODO Auto-generated method stub
        return 0;
    }
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // TODO Auto-generated method stub
        View grid;
        LayoutInflater inflater = (LayoutInflater) mContext
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        if (convertView == null) {
            grid = new View(mContext);
            grid = inflater.inflate(R.layout.grid_single, null);

        } else {
            grid = convertView;

        }

        TextView textView = (TextView) grid.findViewById(R.id.grid_text);
        ImageView imageView = (ImageView)grid.findViewById(R.id.grid_image);
        textView.setText(web[position]);
        imageView.setImageResource(Imageid[position]);

        return grid;
    }

}

这就是我在mainActivity中调用类的方法：

CustomGrid adapter = new CustomGrid(MainActivity.this, web, imageId);
grid=(GridView)findViewById(R.id.grid);
grid.setAdapter(adapter);

任何帮助将不胜感激，谢谢！

Answer 1

import java.util.HashSet;
import java.util.Set;

public class MatrixExamples {
    public static void zeroOut(int[][] myArray) {
        Set<Integer> rowsToZero = new HashSet<>();
        Set<Integer> columnsToZero = new HashSet<>();

        for (int i = 0; i < myArray.length; i++) { 
            for (int j = 0; j < myArray.length; j++) {
                if (myArray[i][j] == 0) {
                    rowsToZero.add(i);
                    columnsToZero.add(j);
                }
            }
        }

        for (int i : rowsToZero) {
            for (int j = 0; j < myArray.length; j++) {
                myArray[i][j] = 0;
            }
        }

        for (int i : columnsToZero) {
            for (int j = 0; j < myArray.length; j++) {
                myArray[j][i] = 0;
            }
        }

        for (int i = 0; i < myArray.length; i++) { // record which rows and                                             // columns will be zeroed
            for (int j = 0; j < myArray.length; j++) {
                System.out.print(myArray[i][j] + ",");
            if(j == myArray.length-1)
                System.out.println();
            }
        }

    }

    public static void main(String[] args) {
        int[][] a = { { 1, 0, 1, 1, 0 }, { 0, 1, 1, 1, 0 }, { 1, 1, 1, 1, 1 },
                { 1, 0, 1, 1, 1 }, { 1, 1, 1, 1, 1 } };
        zeroOut(a);
    }
}

这是我们的线索！只需将一个默认构造函数添加到CustomGrid类。

    Error:Error: This class should provide a default constructor (a public constructor with no arguments) (com.tokom.globol.CustomGrid) [Instantiatable]

Android Studio：无法生成已签名的APK

1 个答案: