Question

我正在尝试转到下面的活动，但是它不起作用。在仿真器上说“项目不断停止”。那是我尝试构建的第一个应用程序，因此，如果您能详细解释，我将不胜感激。

printf

也请参见清单下方。

package com.example.project3;

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.Spinner;

import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;


   public class view extends Fragment {
        public static view newInstance() {

            Bundle args = new Bundle();

            view fragment = new view();
            fragment.setArguments(args);
            return fragment;
        }

        @Nullable
        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
            View v=inflater.inflate(R.layout.activity_view,container,false);
            SQLiteDatabase db;
            db=getActivity().openOrCreateDatabase("employeeTasks.db", Context.MODE_PRIVATE,null);
            crearyllenar(db);
            listviewllenar(v, db);

            Button bfinish = (Button)v.findViewById(R.id.bfinish);
            bfinish.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {

                    Spinner names = (Spinner)getView().findViewById(R.id.names);
                    Spinner dates = (Spinner)getView().findViewById(R.id.dates);

                    Spinner room = (Spinner)getView().findViewById(R.id.room);
                    Spinner cleanbed1 = (Spinner)getView().findViewById(R.id.cleanbed1);
                    Spinner brushfloor1 = (Spinner)getView().findViewById(R.id.brushfloor1);
                    Spinner mopfloor1 = (Spinner)getView().findViewById(R.id.mopfloor1);
                    Spinner cleanmirrow1 = (Spinner)getView().findViewById(R.id.cleanmirrow1);
                    Spinner cleanwindow1 = (Spinner)getView().findViewById(R.id.cleanwindow1);
                    Spinner removedust1 = (Spinner)getView().findViewById(R.id.removedust1);
                    Spinner emptybin1 = (Spinner)getView().findViewById(R.id.emptybin1);


                    EditText comments = (EditText)getView().findViewById(R.id.comments);

                    SQLiteDatabase db1;

                    db1=getActivity().openOrCreateDatabase("employeeTasks.db", Context.MODE_PRIVATE,null);
                    db1.execSQL("insert into employeeTask(names,dates,rooms,cleanbed,brushfloor,mopfloor,cleanmirrow,cleanwindow,removedust,emptybin,comments,commentsinfo) "+
                            "values('"+names.getSelectedItem().toString()+"','"+dates.getSelectedItem().toString()+"','"+room.getSelectedItem().toString()+"','"+cleanbed1.getSelectedItem().toString()+"','"+brushfloor1.getSelectedItem().toString()+"','"+mopfloor1.getSelectedItem().toString()+"','"+cleanmirrow1.getSelectedItem().toString()+"','"+cleanwindow1.getSelectedItem().toString()+"','"+removedust1.getSelectedItem().toString()+"','"+emptybin1.getSelectedItem().toString()+"','"+comments.getText().toString()+"','@@"+comments.getText().toString()+"')");

                    listviewllenar(getView(),db1);
                    names.setSelection(0);
                    dates.setSelection(0);
                    room.setSelection(0);
                    cleanbed1.setSelection(0);
                    brushfloor1.setSelection(0);
                    mopfloor1.setSelection(0);
                    cleanmirrow1.setSelection(0);
                    cleanwindow1.setSelection(0);
                    removedust1.setSelection(0);
                    emptybin1.setSelection(0);
                    comments.setText("");


                }
            });

            return v;
        }

        private int listviewllenar(View v, SQLiteDatabase db) {
            Cursor c2=db.rawQuery("select * from employeeTask where estado=1 order by _id desc",null);
            String[] from=new String[]{"names","dates","rooms","cleanbed","brushfloor","mopfloor","cleanmirrow","cleanwindow","removedust","emptybin","comments","commentsinfo","time","id"};
            int[] to=new int[]{R.id.tnames, R.id.tdates, R.id.trooms, R.id.tcleanbed,  R.id.tbrushfloor, R.id.tmopfloor, R.id.tcleanmirrow,  R.id.tcleanwindow, R.id.tremovedust, R.id.temptybin,  R.id.tcomments, R.id.tcommentsinfo,R.id.ttime, R.id.tid};

            android.widget.ListView lv=(ListView) v.findViewById(R.id.listview);
            SimpleCursorAdapter adapter= new SimpleCursorAdapter(v.getContext(),R.layout.item,c2,from,to,0);
            lv.setAdapter(adapter);
            return 0;
        }

        private int crearyllenar(SQLiteDatabase db) {
            db.execSQL("create table if not exists employeeTask (_id integer primary key autoincrement unique,"+
                    "name text not null,dates text not null,room integer not null,cleanBed text not null,"+
                    "brushFloor text not null,mopFloor text not null,cleanMirrow text not null,cleanWindow text not null,"+
                    "removeDust text not null,emptyBin text not null,comments text not null,commentsInfo text not null,"+
                    "estado integer default 1,time datetime default (datetime(current_timestamp,'localtime'))) ");
            Cursor c1=db.rawQuery("select * from employeeTasks",null);
            if (c1.getCount()<=0){
              db.execSQL("insert into employeeTask(name,dates,room,cleanBed,brushFloor,mopFloor,cleanMirrow,cleanWindow,removeDust,emptyBin,comments,commentsInfo) "+
                        "values('joe','tusday',1,'yes','yes','yes','yes','yes','yes','yes','yes','yes')");

            }
            return 0;
        }
    }

这是我得到的错误：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.project3">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".view"></activity>
        <activity android:name=".View_Lists" />
        <activity android:name=".ListView" />
        <activity android:name=".EmployeeTasks" />
        <activity android:name=".DatabaseHelper" />
        <activity android:name=".Selection" />
        <activity android:name=".Login" />
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Answer 1

首先，您不应命名您的此类视图。类以大写字母开头（按照约定，不是强制性的）。同样，您不应该将您的班级命名为仅视图，如果没有视图，则不要包含任何包含视图的内容。

第二，您正在创建一个片段。如果您尝试使用此类启动活动，那么它将失败，因为活动不是片段。

有关片段here的使用方法，请参阅文档。

无法实例化活动ComponentInfo java.lang.ClassCastException

1 个答案: