安卓SQLite常见错误

Posted 2020-07-05 南尘

利用闲时写了一个简单的Sql语句操作SQLite数据库，在用SimpleCursorAdapter时出了一个异常好久都没解决

Process: com.example.chunchuner.usesqltest405, PID: 31206
java.lang.IllegalArgumentException: column \'_id\' does not exist

 

通过一系列查找资料才发现

//使用SimpleCursorAdapter封装Cursor时候Cursor要求底层数据库的主键列的列名必须为_id
//否则会出现java.lang.IllegalArgumentException异常

代码如下：

package com.example.nanchen.usesqltest405;

import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.CursorAdapter;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;

public class MainActivity extends AppCompatActivity {

    private Button insert;
    private EditText textView_title,textView_content;
    private SQLiteDatabase db;
    private ListView listView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //创建或者打开数据库（此处需要使用绝对路径）
        db = SQLiteDatabase.openOrCreateDatabase(this.getFilesDir().toString()+"/my.db3",null);
        insert = (Button) findViewById(R.id.insert);
        listView = (ListView) findViewById(R.id.listView);
        textView_title = (EditText) findViewById(R.id.title_text);
        textView_content = (EditText) findViewById(R.id.content);
        insert.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String title = textView_title.getText().toString();
                String content = textView_content.getText().toString();
                try {
                    insertData(db, title, content);
                }catch (SQLiteException e){
                    //执行创建数据库表
                    db.execSQL("create table news_inf(_id integer primary key autoincrement, " +
                            "news_title varchar2,news_content varchar2)");
                    insertData(db, title, content);
                }
                Cursor cursor = db.rawQuery("select * from news_inf", null);
                inflateList(cursor);

            }
        });
    }

    private void insertData(SQLiteDatabase db,String title,String content){
        db.execSQL("insert into news_inf values(null,?,?)", new String[]{title, content});
    }

    private void inflateList(Cursor cursor){
        //填充SimpleCursorAdapter
        //使用SimpleCursorAdapter封装Cursor时候Cursor要求底层数据库的主键列的列名必须为_id
        //否则会出现java.lang.IllegalArgumentException异常
        SimpleCursorAdapter adapter = new SimpleCursorAdapter(this,
                android.R.layout.simple_list_item_1,cursor,
                new String[]{"news_title","news_content"},
                new int[]{R.id.title_text,R.id.content},
                CursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER);
        //显示数据
        listView.setAdapter(adapter);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        //退出程序时关闭SQLiteDataBase
        if (db != null && db.isOpen()){
            db.close();
        }
    }
}