public class MainActivity extends Activity implements OnClickListener{    Button btn1;    Button btn2;    Button btn3;    EditText editText1;    EditText editText2;    SQLiteDatabase db;    ListView listView1;    Cursor cursor;        @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        btn1=(Button)findViewById(R.id.button1);        btn2=(Button)findViewById(R.id.button2);        btn3=(Button)findViewById(R.id.button3);        btn1.setOnClickListener(this);        btn2.setOnClickListener(this);        btn3.setOnClickListener(this);                editText1=(EditText)findViewById(R.id.editText1);        editText2=(EditText)findViewById(R.id.editText2);        listView1=(ListView)findViewById(R.id.listView1);        try {            File file= new File(getFilesDir().getCanonicalPath()+"/test.db");                if(file.exists()){                file.delete();            }                        //打开数据库，不存在则创建            db=SQLiteDatabase.openOrCreateDatabase(getFilesDir().getCanonicalPath()+"/test.db", null);            String sql=            "CREATE TABLE t_test ("+            "        _id  INTEGER NOT NULL,"+            "        name  TEXT,"+            "        PRIMARY KEY (_id ASC)"+            "        )";            db.execSQL(sql);        } catch (IOException e) {            // TODO 自动生成的 catch 块            e.printStackTrace();        }    }    public void onClick(View paramView) {        if(paramView==btn1){            int _id=Integer.parseInt(editText1.getText().toString());            String name=editText2.getText().toString();            String sql="select * from t_test where _id="+_id;            Cursor cursor=db.rawQuery(sql, null);            if(cursor.getCount()>0){                Toast.makeText(MainActivity.this, "记录已存在", Toast.LENGTH_SHORT).show();            }else{                sql="INSERT INTO t_test VALUES (?, ?)";                db.execSQL(sql, new Object[]{_id,name});            }        }else if(paramView==btn2){            int _id=Integer.parseInt(editText1.getText().toString());            String name=editText2.getText().toString();            String sql="update t_test set _id=?,name=? where _id=?";            db.execSQL(sql, new Object[]{_id,name,_id});        }else if(paramView==btn3){            int _id=Integer.parseInt(editText1.getText().toString());            String sql="delete from t_test where _id=?";            db.execSQL(sql, new Object[]{_id});            editText1.setText("");            editText2.setText("");        }                cursor=db.rawQuery("select * from t_test", null);        SimpleCursorAdapter adapter=new SimpleCursorAdapter(MainActivity.this,                R.layout.item, cursor, new String[]{"_id","name"}, new int[]{R.id.textView2,R.id.textView4});        listView1.setAdapter(adapter);        listView1.setOnItemClickListener(new OnItemClickListener() {            @Override            public void onItemClick(AdapterView<?> paramAdapterView,                    View paramView, int paramInt, long paramLong) {                if(cursor.moveToPosition(paramInt)){                    editText1.setText(""+cursor.getInt(cursor.getColumnIndex("_id")));                    editText2.setText(cursor.getString(cursor.getColumnIndex("name")));                }                            }        });    }}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent" android:padding="10dp">    <TextView        android:id="@+id/textView1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentLeft="true"        android:layout_alignParentTop="true"        android:layout_marginLeft="15dp"        android:text="ID："        android:textAppearance="?android:attr/textAppearanceMedium" />    <TextView        android:id="@+id/textView2"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignBaseline="@+id/textView1"        android:layout_alignBottom="@+id/textView1"        android:layout_marginLeft="33dp"        android:layout_toRightOf="@+id/textView1"        android:text="001"        android:textAppearance="?android:attr/textAppearanceMedium" />    <TextView        android:id="@+id/textView3"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignBaseline="@+id/textView2"        android:layout_alignBottom="@+id/textView2"        android:layout_marginLeft="17dp"        android:layout_toRightOf="@+id/textView2"        android:text="名字："        android:textAppearance="?android:attr/textAppearanceMedium" />    <TextView        android:id="@+id/textView4"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignBaseline="@+id/textView3"        android:layout_alignBottom="@+id/textView3"        android:layout_marginLeft="27dp"        android:layout_toRightOf="@+id/textView3"        android:text="测试1"        android:textAppearance="?android:attr/textAppearanceMedium" /></RelativeLayout>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    tools:context="${relativePackage}.${activityClass}" >    <Button        android:id="@+id/button2"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignBaseline="@+id/button1"        android:layout_alignBottom="@+id/button1"        android:layout_centerHorizontal="true"        android:text="修改" />    <Button        android:id="@+id/button3"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignBaseline="@+id/button2"        android:layout_alignBottom="@+id/button2"        android:layout_alignParentRight="true"        android:layout_marginRight="21dp"        android:text="删除" />    <Button        android:id="@+id/button1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_below="@+id/editText2"        android:layout_marginTop="11dp"        android:text="添加" />    <EditText        android:id="@+id/editText2"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignBottom="@+id/textView2"        android:layout_alignParentRight="true"        android:layout_toRightOf="@+id/button1"        android:ems="10" >        <requestFocus />    </EditText>    <EditText        android:id="@+id/editText1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignLeft="@+id/editText2"        android:layout_alignParentRight="true"        android:layout_alignTop="@+id/textView1"        android:ems="10" />    <TextView        android:id="@+id/textView2"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignRight="@+id/button1"        android:layout_below="@+id/editText1"        android:layout_marginTop="19dp"        android:text="名字"        android:textAppearance="?android:attr/textAppearanceMedium" />    <TextView        android:id="@+id/textView1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignLeft="@+id/textView2"        android:layout_alignParentTop="true"        android:layout_marginTop="21dp"        android:layout_toLeftOf="@+id/editText1"        android:text="id"        android:textAppearance="?android:attr/textAppearanceMedium" />    <ListView        android:id="@+id/listView1"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_alignParentRight="true"        android:layout_below="@+id/button2" >    </ListView></RelativeLayout>