Question

这是我的应用程序（基本），通过对话框TextView设置EditText的值。

我想在应用程序启动的第一次将TextView设置为0，然后我想保存值的状态，这样当你打开它时，相同的值是那里。

我会给你留下我的代码：

public class MainActivity extends AppCompatActivity {
private int currentMoney;



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

}

@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
    super.onRestoreInstanceState(savedInstanceState);
    // Restore UI state from the savedInstanceState.
    // This bundle has also been passed to onCreate.
    SharedPreferences mDefaultPreferences = PreferenceManager.getDefaultSharedPreferences(this);
    int current = savedInstanceState.getInt("current");
    if (mDefaultPreferences.getBoolean("first_launch", true))
    {
        mDefaultPreferences.edit().putBoolean("first_launch", false).commit();
        //Put the code here of your first launch
        currentMoney = 0;
    }
    else
    {
        //Not the first launch
        currentMoney = current;
    }

}

我将它们分开以使任何事情更清楚

public void plus(View view) {
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setView(R.layout.pluslayout);
    builder.setPositiveButton(R.string.add, new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int id) {
            // User clicked OK button
            TextView money = (TextView) findViewById(R.id.textCool);
            EditText transaction = (EditText) ((AlertDialog) dialog).findViewById(R.id.editText);
            int earn = Integer.parseInt(transaction.getText().toString());
            int finalEarn = currentMoney + earn;
            String earnFinal = String.valueOf(finalEarn);
            money.setText(earnFinal);
        }
    });
    builder.setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int id) {
            // User cancelled the dialog
        }
    });
    AlertDialog dialog = builder.show();
}

public void minus(View view) {
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setView(R.layout.minuslayout);
    builder.setPositiveButton(R.string.remove, new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int id) {
            // User clicked OK button
            TextView money = (TextView) findViewById(R.id.textCool);
            EditText transaction = (EditText) ((AlertDialog) dialog).findViewById(R.id.editText);
            int loss = Integer.parseInt(transaction.getText().toString());
            int currentMoney = Integer.parseInt(money.getText().toString());
            int finalLoss = currentMoney - loss;
            String lossFinal = String.valueOf(finalLoss);
            money.setText(lossFinal);
        }
    });
    builder.setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int id) {
            // User cancelled the dialog
        }
    });
    AlertDialog dialog = builder.show();
}

最后

@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
    super.onSaveInstanceState(savedInstanceState);
    // Save UI state changes to the savedInstanceState.
    // This bundle will be passed to onCreate if the process is
    // killed and restarted.
    TextView money = (TextView) findViewById(R.id.textCool);
    int currentMoney = Integer.parseInt(money.getText().toString());
    savedInstanceState.putInt("current", currentMoney);
}

}

我会留下你的MainActivity Java文件，因为这可能就是问题所在。谢谢。

Answer 1

我建议使用SharedPreferences来存储和检索TextViews的值。您可能已经熟悉此过程，因为您从SharedPreferences对象中检索了一个值，但以防万一，这是我的某个应用程序的片段...

SharedPreferences.Editor editor = mDefaultPreferences.edit();
editor.putString("last known value", money.getText();
editor.apply();  //this will immediately write your changes in-memory, then start an asynchronous task to write the values to permanent storage on the disc.

让价值回归......

String storedValue = mDefaultPreferences.getString("last known value", 0);
money.setText(storedValue);

Answer 2

在Developer guide中，它表示builder.create（）;应该在链接参数后出现。我认为builder.show（）只显示值，不会存储它。

无法恢复价值，为什么？

2 个答案: