intent.putExtra 在片段中返回正确的值，但在活动中返回 null

Question

我需要从MainActivity获取account以添加到AddModifyTask中的命令。 我在MainActivity中使用intent.putExtra并在AddModifyTask中通过getIntent.getStringExtra获取account ，但它始终返回null ，与Fragment中的getIntent.getStringExtra仍然相同，然后它返回正确的account值，谁能帮助我

MainAcitivy，我需要从这里传递account

Boolean result = db.checkUserNamePassword(account, password);
                    if(result==true) {
                        Intent intent = new Intent(MainActivity.this, HomeActivity.class);
                        intent.putExtra("account", account);
                        Intent intent1 = new Intent(MainActivity.this, AddModifyTask.class);
                        intent1.putExtra("account", account);
                        startActivity(intent);

我需要将account传递到的 AddModifyTask 活动，但它只返回null

public void saveTask(View v) {
        /*Checking for Empty Task*/
        if (edit_text.getText().toString().trim().length() > 0) {
            if (isModify) {
                String account = getIntent().getStringExtra("account");
                mydb.updateTask(task_id, edit_text.getText().toString(), new SimpleDateFormat("yyyy-MM-dd").format(calendar.getTime()), account);
                Toast.makeText(getApplicationContext(), "Task updated.", Toast.LENGTH_SHORT).show();
            } else {
                String account = getIntent().getStringExtra("account");
                mydb.insertTask(edit_text.getText().toString(), new SimpleDateFormat("yyyy-MM-dd").format(calendar.getTime()), account);
                Toast.makeText(getApplicationContext(), "Added.", Toast.LENGTH_SHORT).show();
            }
            finish();

        } else {
            Toast.makeText(getApplicationContext(), "No empty.", Toast.LENGTH_SHORT).show();
        }

仍然与Fragment中的getIntent.getStringExtra相同，然后它返回正确的account值

public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.fragment_profile, container, false);
        TextView textViewAccount = v.findViewById(R.id.textViewAccount);

        String account = getActivity().getIntent().getStringExtra("account");
        textViewAccount.setText(account);
        }
        return v;
    }

数据库中的函数insertTask和updateTask ，是数据库中的语句还是AddModifyTask中的getIntent或两者都有问题？

public boolean insertTask(String task, String task_at, String account) {
    Date date;
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put("task", task);
    contentValues.put("task_at", task_at);
    contentValues.put("status", 0);
    contentValues.put("user", account);
    db.insert(TB_TASK, null, contentValues);
    return true;
}

    public boolean updateTask(String id, String task, String task_at, String account) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues contentValues = new ContentValues();
        contentValues.put("task", task);
        contentValues.put("task_at", task_at);
        contentValues.put("user",  account);
        db.update(TB_TASK, contentValues, "id = ? ", new String[]{id});
        return true;
    }

请帮忙！

Answer 1

可能，您的问题在这里：

Intent intent = new Intent(MainActivity.this, HomeActivity.class);
intent.putExtra("account", account);
Intent intent1 = new Intent(MainActivity.this, AddModifyTask.class);
intent1.putExtra("account", account);
startActivity(intent);

您正在为AddModifyTask创建intent1 ，但正在为HomeActivity创建intent 。

尝试类似：

Intent intent = new Intent(MainActivity.this, AddModifyTask.class);
intent.putExtra("account", account);
startActivity(intent);

Answer 2

我使用SharedPreferences而不是intent.putExtra

Boolean result = db.checkUserNamePassword(account, password);
                    if(result==true) {
                        Intent intent = new Intent(MainActivity.this, HomeActivity.class);
                        intent.putExtra("account", account);
                        SharedPreferences sharedPref = getSharedPreferences("account", MODE_PRIVATE);
                        SharedPreferences.Editor editor = sharedPref.edit();
                        editor.putString("account", account);
                        editor.apply();
                        startActivity(intent);

在 AddModifyTask

public void saveTask(View v) {
        /*Checking for Empty Task*/
        if (edit_text.getText().toString().trim().length() > 0) {
            if (isModify) {
                SharedPreferences sharedPreferences = getSharedPreferences("account", MODE_PRIVATE);
                String account = sharedPreferences.getString("account","");
                mydb.updateTask(task_id, edit_text.getText().toString(), new SimpleDateFormat("yyyy-MM-dd").format(calendar.getTime()), account);
                Toast.makeText(getApplicationContext(), "Tác vụ đã được cập nhật.", Toast.LENGTH_SHORT).show();
            } else {
                SharedPreferences sharedPreferences = getSharedPreferences("account", MODE_PRIVATE);
                String account = sharedPreferences.getString("account","");
                mydb.insertTask(edit_text.getText().toString(), new SimpleDateFormat("yyyy-MM-dd").format(calendar.getTime()), account);
                Toast.makeText(getApplicationContext(), "Đã thêm.", Toast.LENGTH_SHORT).show();
            }
            finish();