用Android Studio开发一个记账本的代码

好的，下面是一个简单的记账本应用的代码示例，你可以参考一下：

AccountItem.java：

public class AccountItem {
    private String name;
    private float amount;

    public AccountItem(String name, float amount) {
        this.name = name;
        this.amount = amount;
    }

    public String getName() {
        return name;
    }

    public float getAmount() {
        return amount;
    }
}

AccountAdapter.java：

public class AccountAdapter extends BaseAdapter {
    private List<AccountItem> accountList;
    private Context context;

    public AccountAdapter(Context context, List<AccountItem> accountList) {
        this.context = context;
        this.accountList = accountList;
    }

    @Override
    public int getCount() {
        return accountList.size();
    }

    @Override
    public Object getItem(int position) {
        return accountList.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        if (convertView == null) {
            convertView = LayoutInflater.from(context).inflate(R.layout.item_account, parent, false);
        }

        TextView nameTv = convertView.findViewById(R.id.name_tv);
        TextView amountTv = convertView.findViewById(R.id.amount_tv);

        AccountItem item = accountList.get(position);
        nameTv.setText(item.getName());
        amountTv.setText(String.valueOf(item.getAmount()));

        return convertView;
    }
}

MainActivity.java：

public class MainActivity extends AppCompatActivity {
    private EditText nameEt;
    private EditText amountEt;
    private Button saveBtn;
    private ListView accountLv;

    private List<AccountItem> accountList;
    private AccountAdapter accountAdapter;

    private SharedPreferences sharedPreferences;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        nameEt = findViewById(R.id.name_et);
        amountEt = findViewById(R.id.amount_et);
        saveBtn = findViewById(R.id.save_btn);
        accountLv = findViewById(R.id.account_lv);

        accountList = new ArrayList<>();
        accountAdapter = new AccountAdapter(this, accountList);
        accountLv.setAdapter(accountAdapter);

        sharedPreferences = getSharedPreferences("account_list", MODE_PRIVATE);
        loadAccountList();

        saveBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String name = nameEt.getText().toString();
                float amount = Float.parseFloat(amountEt.getText().toString());

                AccountItem item = new AccountItem(name, amount);
                accountList.add(item);
                accountAdapter.notifyDataSetChanged();

                saveAccountList();
            }
        });
    }

    private void saveAccountList() {
        SharedPreferences.Editor editor = sharedPreferences.edit();
        Gson gson = new Gson();
        String json = gson.toJson(accountList);
        editor.putString("account_list", json);
        editor.apply();
    }

    private void loadAccountList() {
        Gson gson = new Gson();
        String json = sharedPreferences.getString("account_list", "");
        Type type = new TypeToken<List<AccountItem>>() {}.getType();
        accountList = gson.fromJson(json, type);
        if (accountList == null) {
            accountList = new ArrayList<>();
        }
        accountAdapter = new AccountAdapter(this, accountList);
        accountLv.setAdapter(accountAdapter);
    }

    @Override
    protected void onStop() {
        super.onStop();
        saveAccountList();
    }
}

上面的代码示例包含了一个 AccountItem 类，表示一个账单条目，一个 AccountAdapter 类，用于将账单信息显示在 ListView 中，以及一个 MainActivity 类，实现了记账本应用的主界面和核心逻辑。注意，在实现保存和读取账单信息时，我们使用了 SharedPreferences 来实现数据的持久化存储。