android - savedInstanceState返回null

有人能解释一下为什么savedInstanceState中的值为空吗？
我有3个小部件，一个edittext，按钮和textview。这个人输入他们想要的东西。这个短语会在文本视图中弹出。我想在翻动电话时保留输入。我试图保存状态，但是当活动被重新创建时，我的祝酒词说它是空的：

public class MainActivity extends AppCompatActivity {
private EditText input;
private TextView output;
private Button button;
private String newString = "";

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

    input = (EditText)findViewById(R.id.input);
    output = (TextView) findViewById(R.id.output);
    button = (Button)findViewById(R.id.button);

    if (savedInstanceState!=null){
        Toast.makeText(this, "SAVED IS " + savedInstanceState.getString("example"), Toast.LENGTH_SHORT).show();
    }


    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            newString = input.getText().toString();
            output.setText(newString);
        }
    });

}

@Override
public void onSaveInstanceState(Bundle outState, PersistableBundle outPersistentState) {
    super.onSaveInstanceState(outState, outPersistentState);
    outState.putString("example",newString);
}}

最佳答案

您需要使用此函数onSaveInstanceState(Bundle outState)，即不使用PersistableBundle outPersistentState的函数

@Override
public void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState, outPersistentState);
    outState.putString("example",newString);
}

void onSaveInstanceState (Bundle outState, PersistableBundle outPersistentState)只有在清单内的活动标记中指定了属性persistableMode时，才会调用此函数
您可以阅读更多about it here

关于android - savedInstanceState返回null，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/41511162/