1

我知道这个问题已经被问了很多，但我不明白为什么 onSaveInstanceState 对我不起作用。这可能是一些愚蠢的事情，但我希望你们中的一些人能在这里帮助我。无论如何，这是我的代码：

public class Main extends Activity implements OnClickListener, OnKeyListener {

EditText textitem;
Button buttonadd;
ListView listitems;

ArrayList<String> ToDo;
ArrayAdapter<String> AA;
ArrayList<String> MyArrayList;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    textitem = (EditText) findViewById(R.id.textitem);
    buttonadd = (Button) findViewById(R.id.buttonadd);
    listitems = (ListView) findViewById(R.id.listitems);

    buttonadd.setOnClickListener(this);
    textitem.setOnKeyListener(this);

    ToDo = new ArrayList<String>();
    AA = new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1, ToDo);
    listitems.setAdapter(AA);

}

@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
    savedInstanceState.putStringArrayList("MyArrayList", ToDo);
    super.onSaveInstanceState(savedInstanceState);
}

@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
    super.onRestoreInstanceState(savedInstanceState);
    ArrayList<String> ToDo = savedInstanceState.getStringArrayList("MyArrayList");
}

private void addItem(String item) {
    if (item.length() > 0) {
        this.ToDo.add(item);
        this.AA.notifyDataSetChanged();
        this.textitem.setText("");
    }
}

public void onClick(View v) {
    if (v == this.buttonadd) {
        this.addItem(this.textitem.getText().toString());
    }
}

public boolean onKey(View v, int keyCode, KeyEvent event) {
    if (event.getAction() == KeyEvent.ACTION_DOWN
            && keyCode == KeyEvent.KEYCODE_DPAD_CENTER) {
        this.addItem(this.textitem.getText().toString());
    }
    return false;
}

}

4

3 回答 3

0

您将其保存在局部变量中，为什么？可以试试这个

@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
    super.onRestoreInstanceState(savedInstanceState);
    this.ToDo = savedInstanceState.getStringArrayList("MyArrayList");
}

通常你在 onCreate 中恢复你的状态。也可以在 onRestoreInstanceState 中恢复它，但不是很常见。（onRestoreInstanceState 在 onStart 之后调用，而 onCreate 在 onStart 之前调用。

来自：onSaveInstanceState() 和 onRestoreInstanceState()

于 2012-05-30T09:07:18.603 回答
0

您在“onRestoreInstanceState()”回调中提取保存的值，但实际上您并没有对它们做任何事情。

ArrayList<String> ToDo = savedInstanceState.getStringArrayList("MyArrayList");

您需要将这些值包装在适配器中并将其分配给列表，就像您在 onCreate() 末尾执行的操作一样。

于 2012-05-30T09:10:35.507 回答
0 
public class Main extends Activity implements OnClickListener, OnKeyListener {

EditText textitem;
Button buttonadd;
ListView listitems;

ArrayList<String> ToDo;
ArrayAdapter<String> AA;
ArrayList<String> MyArrayList;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    textitem = (EditText) findViewById(R.id.textitem);
    buttonadd = (Button) findViewById(R.id.buttonadd);
    listitems = (ListView) findViewById(R.id.listitems);

    buttonadd.setOnClickListener(this);
    textitem.setOnKeyListener(this);

    if(savedInstanceState!=null)
     {
       ToDo = savedInstanceState.getStringArrayList("MyArrayList");
     }
    else
     {
       ToDo = new ArrayList<String>();
     }
    AA = new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1, ToDo);
    listitems.setAdapter(AA);

}

@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
    savedInstanceState.putStringArrayList("MyArrayList", ToDo);
    super.onSaveInstanceState(savedInstanceState);
}


private void addItem(String item) {
    if (item.length() > 0) {
        this.ToDo.add(item);
        this.AA.notifyDataSetChanged();
        this.textitem.setText("");
    }
}

public void onClick(View v) {
    if (v == this.buttonadd) {
        this.addItem(this.textitem.getText().toString());
    }
}

public boolean onKey(View v, int keyCode, KeyEvent event) {
    if (event.getAction() == KeyEvent.ACTION_DOWN
            && keyCode == KeyEvent.KEYCODE_DPAD_CENTER) {
        this.addItem(this.textitem.getText().toString());
    }
    return false;
}

希望这会帮助你。维普尔

于 2012-05-30T09:15:54.903 回答