android - 如何在 onSaveInstanceState 中使用变量

Question

这个问题在这里已经有了答案:

How can I save an activity state using the save instance state? (35 个回答)

关闭 9年前。

我刚开始在 android 上学习编程，但在 onSaveInstanceState 处使用变量时遇到了问题。这是我的代码:

int resultCode;

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

    if (savedInstanceState != null) {
        super.onRestoreInstanceState(savedInstanceState);

        int resultCode = savedInstanceState.getInt("resultCode");
    } 

    Button btnOpenWithResult = (Button) findViewById(R.id.btnOpenWithResult);
    btnOpenWithResult.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View arg0) {
            Intent myIntent = new Intent(flashlight.this, ThirdActivity.class);
            startActivityForResult(myIntent, 1);
        }
    });
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    switch (resultCode) {
    case 1:   
         /** option 1  */            
        break;
    case 2:
         /** option 2 */
        break;
}

@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
    savedInstanceState.putInt("resultCode", resultCode);
    super.onSaveInstanceState(savedInstanceState);
}

我想使用 onSaveInstanceState 保存变量 resultCode 并在恢复 Activity 后再次使用它...

(对不起我的英语水平)

Answer 1

Cyren... 1) 我认为没有理由在 onCreate 中调用 super.onRestoreInstanceState。在方法中进行调用是有意义的

public void onRestoreInstanceState(Bundle saved) {
    super.onRestoreInstanceState(saved);

2) 声明:

   int resultCode = savedInstanceState.getInt("resultCode");

正在“隐藏”变量:

int resultCode;

早先声明过。所以有两个版本的变量 resultCode 具有不同的范围。也许你的意思是编码:

int resultCode;

stuff here

    resultCode = savedInstanceState.getInt("resultCode");

希望对您有所帮助，日航