Question

好的，这就是整个代码

这是MainActivity.java

  $('.lt-buttonContainer button').click(function () {

    var $this = $(this);

    $('.lt-buttonContainer button').removeClass ("button1Clicked");
    $this.addClass("button1Clicked");
})

这是DPAdapter类代码：

package com.gobtron.database_test;

import android.database.Cursor;
import android.database.DatabaseUtils;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;


public class MainActivity extends ActionBarActivity {

    DBAdapter myDb;



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

        openDB();
        populateListView();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    private void openDB() {
        myDb = new DBAdapter(this);
        myDb.open();
    }

    public void onClick_ViewData (View v){
        openDB();
        populateListView();
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }


    private void populateListView() {
        Cursor cursor = myDb.getAllRows();
       // DatabaseUtils.dumpCursor(cursor);
        String[] fromFieldNames = new String[] {DBAdapter.KEY_ROWID, DBAdapter.KEY_NOM};
        int[] toViewIDs = new int[] {R.id.textView2, R.id.textView3};
        SimpleCursorAdapter myCursorAdapter;
        myCursorAdapter = new SimpleCursorAdapter(getBaseContext(), R.layout.item_layout, cursor, fromFieldNames, toViewIDs, cursor.getCount());
        ListView myList = (ListView) findViewById(R.id.listView);
        myList.setAdapter(myCursorAdapter);

    }
}

我不知道为什么我的光标是空的......我认为它正确地打开了数据库，也打开了表格。

嗯......我是java的新手，所以这可能是我不知道的愚蠢。

Answer 1

您正在尝试使用键KEY_MORTH插入值，但表中没有此键的字段这样：

 "CREATE TABLE " + DATABASE_TABLE
            + " (" + KEY_ROWID + " INTEGER PRIMARY KEY , "
            + KEY_NOM + " TEXT NOT NULL, "
            + KEY_DESC + " TEXT"
            + ");";

需要

 "CREATE TABLE " + DATABASE_TABLE
            + " (" + KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, "
            + KEY_NOM + " TEXT NOT NULL, "
            + KEY_DESC + " TEXT, "
            + KEY_MORTH + " TEXT "
            + ");";

您需要更新数据库版本或清除数据才能使其生效

Answer 2

好的，事实证明我的数据库只是放错了地方。我需要打开Android Device Monitor，然后转到File Explorer，然后将我现有的数据库放到/ data / data / my package name / databases /

ListView没有在Android应用中显示任何内容

2 个答案: