Question

你们可以帮我检查问题出在哪里吗？我为 LastTxnNo 设置了一个循环，但不会自动增加。这是初始化数据库。

dbHelper = new dbOpenHelper(this);
        mSQLiteHelper = new dbOpenHelper(this);
        mModels = new ArrayList<>();
        mAdapter = new settingAdapter(this, R.layout.row_setting, mModels);
        listView1.setAdapter(mAdapter);

我有两个表，这是“ Donation_Details”表，TxnNo应该为“ A0010001”或“ 0001”

这是“信息”表

'Donation_Details'TxnNo应该是'Information'单位代码+ lastTxnNo，表示 TxnNo应该为“ A0010001”。当我单击按钮时，lastTxnNo将增加，并且将更改为“ A0010002”。但是我想我错过了一些逻辑。

 Db_Save.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                Model txn = new Model();// initialize your model class first
                SettingModel txnSec = new SettingModel();

                BigDecimal paidAmt = new BigDecimal(D_Amount.getText().toString()).setScale(2, RoundingMode.HALF_UP);
                txn.setName(D_Name.getText().toString());
                txnSec.setLastTxnNo(D_Txn.getText().toString());
                txn.setTxnDate(Select_Date.getText().toString());
                txn.setAmount(paidAmt);
                txn.setDescription1(D_Description.getSelectedItem().toString());
                txn.setDescription2(Ds_Description.getText().toString());

                try {
                    SQLiteDatabase db = dbHelper.getWritableDatabase();
                    ContentValues cv = new ContentValues();
                    cv.put("name", txn.getName());
                    cv.put("TxnNo", String.format("%04d", i));
                    cv.put("TxnDate", txn.getTxnDate());
                    cv.put("Amount", txn.getAmount().toPlainString());
                    cv.put("Description1", txn.getDescription1());
                    cv.put("Description2", txn.getDescription2());
                    db.insert("Donation_Details", null, cv);
                    db.close();

                    SharedPreferences app_preferences = PreferenceManager.getDefaultSharedPreferences(Donation_Page.this);
                    SharedPreferences.Editor editor = app_preferences.edit();
                    int i = app_preferences.getInt("key", 0);
                    i = ++i;
                    txnSec.setLastTxnNo(i + "");
                    SQLiteDatabase dbSec = dbHelper.getWritableDatabase();
                    ContentValues cvSec = new ContentValues();
                    cvSec.put("TxnNo", String.format("%04d", i));
                    editor.putInt("key", i).commit();
                    dbSec.insert("Information", null, cvSec);
                    dbSec.close();

                    Toast.makeText(Donation_Page.this, "Add successfully", Toast.LENGTH_SHORT).show();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });

Answer 1

您已经声明了方法内部的变量，该方法正在从preference获取值，因此每次新的局部变量（通过按下按钮进行声明）都从首选项获取值0，所以要么

在方法外声明i
或将更新值保存回首选项

int i = app_preferences.getInt("key", 0);
i++; // no need of i = ++i;
editor.putInt("key",i);
editor.commit(); // save value into preference

或使用

// declare i outside method
private int i = 0;

... someMethod(){
    Db_Save.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                // ... code

                        i++;
                // ... code
                }
            });
  }

循环失败，不会增加数量，android studio

1 个答案: