onSaveInstanceState在onCreate之后不可变

Question

您好，有人可以向我解释我在做什么错，因为每次我更改屏幕方向时，都无法从saveInstanceState获取一个变量，即int“ score”，它将重置该变量。

int score;
EditText et;
String etString;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    et = (EditText) findViewById(R.id.editText);
    if (savedInstanceState != null) {
        score = savedInstanceState.getInt("score");
        et.setText(savedInstanceState.getString("etText"));
        Log.d("TEST2", "score " + score);
    } else {
        score = 0;
    }

}

@Override
public void onSaveInstanceState(Bundle outState, PersistableBundle outPersistentState) {
    super.onSaveInstanceState(outState, outPersistentState);

    etString = et.getText().toString();
    outState.putString("etText", etString);
    outState.putInt("score", score);
    Log.d("TEST", "score " + score);
}

public void performAction(View v) {
    switch (v.getId()) {
    case R.id.button:
        score += 1;
        break;
    case R.id.button2:
        Toast.makeText(getApplicationContext(), "Score: " + score, Toast.LENGTH_LONG).show();
        break;
    }

}

如果您知道解决方案，请提供帮助。

Answer 1

您使用的是Lollipop中的方法，请更改为自Android 1.0起可用的版本

@Override
public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);

看到不同的方法签名？

Answer 2

您应该实现onRestoreInstanceState而不是在onCreate中获取价值。 仅当存在要还原的保存状态时，系统才调用onRestoreInstanceState（），因此您无需检查Bundle是否为null。

Answer 3

public class OrientationChangeActivity extends Activity {

private EditText edtUser;

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

    edtUser = (EditText) findViewById(R.id.edtUsername);



    if (savedInstanceState != null /*&& savedInstanceState.getString("edt") != null*/) {
        edtUser.setText(savedInstanceState.getString("edt"));
        Log.e("Demo","==================================="+savedInstanceState.getString("edt"));
    }
}

@Override
protected void onSaveInstanceState(Bundle outState) {
    outState.putString("edt", edtUser.getText().toString());
    super.onSaveInstanceState(outState);
}

}