Question

我有三个活动，第一个用于从数据库中保存一些值，第二个显示列表视图，当我单击该列表视图中的任何项目时，我将跳转到第三个活动，能够编辑我选择的项目，在更新数据库中的数据后，新数据将显示在第二个活动中，但是当我返回到第一个活动时，没有任何内容被刷新。如何在第一个活动中获取更新的数据太？任何帮助将不胜感激。

第二个活动代码：

    import android.content.ContentValues;
    import android.content.Context;
    import android.content.Intent;
    import android.database.Cursor;
    import android.database.sqlite.SQLiteDatabase;
    import android.os.Bundle;
    import android.support.v7.app.AppCompatActivity;
    import android.util.Log;
    import android.view.Menu;
    import android.view.MenuInflater;
    import android.view.MenuItem;
    import android.view.View;
    import android.widget.AdapterView;
    import android.widget.ListAdapter;
    import android.widget.ListView;
    import android.widget.Toast;

    public class SetupActivity extends AppCompatActivity {

        private Context context;
        static String extra = "values";
        ListView mListView;

        final String[] setItems = {"name","birthday","type","sex"};

        @Override
        public void onCreate(Bundle savedInstance){
            super.onCreate(savedInstance);
            setContentView(R.layout.setuplist);
            mListView = (ListView)findViewById(R.id.listview);

            context = this;
            updateView();

        }

        private void updateView(){
            DogDatabaseHelper dbHelper= new DogDatabaseHelper(getApplicationContext());
            SQLiteDatabase db = dbHelper.getWritableDatabase();
            Cursor cursor = db.query("Dog",null,null,null,null,null,null,null);
            if(cursor.moveToFirst()){
                String name = cursor.getString(cursor.getColumnIndex("name"));
                String birthday = cursor.getString(cursor.getColumnIndex("birthday"));
                String size = cursor.getString(cursor.getColumnIndex("size"));
                String sex = cursor.getString(cursor.getColumnIndex("sex"));

                final String[] setValues = {name,birthday,size,sex};
                ListAdapter listAdapter = new CustomAdapter(this,setItems,setValues);
                mListView.setAdapter(listAdapter);

                mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                    @Override
                    public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) {
                        String setupItemValue = setValues[position];
                        String setupItem = setItems[position];
                        Intent intent;
                        if(setupItem.equals("name")){
                            intent = new Intent(SetupActivity.this,ChangeName.class);
                            intent.putExtra(extra,setupItemValue);
                            startActivityForResult(intent,1);
                        } else if(setupItem.equals("birthday")){
                            intent = new Intent(SetupActivity.this,ChangeBirthday.class);
                            intent.putExtra(extra,setupItemValue);
                            startActivityForResult(intent,2);
                        }else if(setupItem.equals("type")){
                            intent = new Intent(SetupActivity.this,ChangeType.class);
                            intent.putExtra(extra,setupItemValue);
                            startActivityForResult(intent,3);
                        }else{
                            intent = new Intent(SetupActivity.this,ChangeSex.class);
                            intent.putExtra(extra,setupItemValue);
                            startActivityForResult(intent,4);
                        }

                    }
                });
            }
            cursor.close();
        }

        @Override
        protected void onActivityResult(int requestCode,int resultCode,Intent data){

            DogDatabaseHelper dbHelper= new DogDatabaseHelper(getApplicationContext());
            SQLiteDatabase db = dbHelper.getWritableDatabase();
            Cursor cursor = db.query("Dog",null,null,null,null,null,null,null);
            switch (requestCode){
                case 1:
                    if (resultCode == RESULT_OK){

                        ContentValues cv = new ContentValues();
                        cv.put("name",data.getStringExtra("return_name"));
                        db.update("dog",cv,"id=?",new String[]{"1"});

                    }
                    break;
                case 2:
                    Toast.makeText(this, "Update2", Toast.LENGTH_SHORT).show();
                    if(resultCode == RESULT_OK){
                        ContentValues cv = new ContentValues();
                        cv.put("birthday",data.getStringExtra("return_birthday"));
                        db.update("dog",cv,"id=?",new String[]{"1"});

                    }
                    break;
                case 3:
                    Toast.makeText(this, "Update3", Toast.LENGTH_SHORT).show();
                    if(resultCode == RESULT_OK){
                        ContentValues cv = new ContentValues();
                        cv.put("size",data.getStringExtra("return_type"));
                        db.update("dog",cv,"id=?",new String[]{"1"});
                    }
                    break;
                case 4:

                    if(resultCode == RESULT_OK){
                        ContentValues cv = new ContentValues();
                        cv.put("sex",data.getStringExtra("return_sex"));
                        Toast.makeText(this, data.getStringExtra("return_sex"), Toast.LENGTH_SHORT).show();
                        int r = db.update("dog",cv,"id=?",new String[]{"1"});
                        if(r != 1){
                            Toast.makeText(this, "Update3", Toast.LENGTH_SHORT).show();
                        }
                    }
                    break;

            }
            db.close();
            updateView();
        }

        @Override
        public boolean onCreateOptionsMenu(Menu menu){
            MenuInflater inflater = getMenuInflater();
            inflater.inflate(R.menu.add,menu);
            return true;
        }
        @Override
        public boolean onOptionsItem

    Selected(MenuItem item){
            int id = item.getItemId();
            if(id == R.id.add){

            }
            return super.onOptionsItemSelected(item);
        }
    }

Answer 1

您应该使用startActivityForResult(intent,requestCode)打开第二个活动，然后您可以在第一个活动中实现onActivityResult(...)，您可以再次从db获取数据并刷新视图。

android如何在更新数据库后刷新我的主要活动？

1 个答案: