Android 如何在方向更改时使用onSaveInstanceState和onRestoreInstanceState保存状态

我读了几乎所有关于堆栈溢出中onSaveInstanceState和onRestoreInstanceState的文章，但我无法解决我的问题
我在main.java中有一个文本视图和按钮，当您单击按钮时（a是一个int变量），变量的值将增加并显示在文本视图中，但是，当我旋转手机（方向改变）时，文本视图将重置

我重写了onSaveInstanceState和onRestoreInstanceState，但它不起作用。 还有一件事，我有专门的layout-land.xml文件用于横向视图

这是我的密码

 import android.app.Activity; 
 import android.graphics.Typeface; 
 import android.os.Bundle;
 import android.view.View;
 import android.widget.Button;
 import android.widget.TextView;

 public class main extends Activity {
     /** Called when the activity is first created. */   
   public int a = 0;     
   public String fonts="TAHOMA.TTF";

   TextView tv = (TextView) findViewById(R.id.salavat);      
   Button b = (Button) findViewById(R.id.showsalavat);

   @Override
   public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.main);
       b.setOnClickListener(new Button.OnClickListener() {
            public void onClick(View arg0) {
               a++;
               tv.setText(""+a);
            }
       });
   }
   @Override        
   protected void onSaveInstanceState(Bundle SavedInstanceState) {
      super.onSaveInstanceState(SavedInstanceState);            
      SavedInstanceState.putInt("salavat-count", a);
   }
   @Override    
   protected void onRestoreInstanceState(Bundle savedInstanceState) {
       super.onRestoreInstanceState(savedInstanceState);     
       a= savedInstanceState.getInt ("salavat-count");   
   } 
}

这里是我的main.xml

我真的需要一些帮助。

---

非常感谢您的帮助。

作为更新，您可以设置

freezesText=“true”

但是，当您开始在方向更改时保存大量对象时，拥有一个表示您的状态的内部类会更好

使用内部类，它将如下所示。您可以想象，当您有越来越多的状态要保存时，内部类使处理程序变得更加容易（不那么混乱）

  private static class State implements Serializable {

    private static final String STATE = "com.your.package.classname.STATE";

    private String yourTextViewText;

    public State(String yourTextViewText) {
        this.yourTextViewText = yourTextViewText;
    }

    public String getYourTextViewText() {
        return yourTextViewText;
    }
}

@Override
protected void onSaveInstanceState(Bundle outState) {
    State s = new State(yourTextView.getText().toString());

    outState.putSerializable(State.STATE, s);

    super.onSaveInstanceState(outState);
}

@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
    super.onRestoreInstanceState(savedInstanceState);

    State s = (State) savedInstanceState.getSerializable(State.STATE);

    yourTextView.setText(s.getYourTextViewText());
}

---

您需要使用保存的值重建视图组件。 用保存的值填充textview

@Override   
protected void onRestoreInstanceState(Bundle savedInstanceState) {
  super.onRestoreInstanceState(savedInstanceState);
  a = savedInstanceState.getInt ("salavat-count");
  tv.setText(""+a);
}

---

你真的想使用这些方法吗

这是一种解决问题的方法，只需将其放入清单文件中即可

<activity android:name="package.subpackage.xptoactivity" android:configChanges="orientation"></activity>

---

如果您这样做，当您更改方向时，您的活动将不会重新加载所有视图并重置其值

我认为此代码对您有帮助

public class MainActivity extends Activity 
{

    protected void onSaveInstanceState(Bundle outState) 
    {
        super.onSaveInstanceState(outState);
        System.out.println("TAG, onSavedInstanceState");

        final TextView text = (TextView)findViewById(R.id.textView1);
        CharSequence userText = text.getText();
        outState.putCharSequence("savedText", userText);
    }
    protected void onRestoreInstanceState(Bundle savedState) 
    {       
        System.out.println("TAG, onRestoreInstanceState");
        final TextView text = (TextView)findViewById(R.id.textView1);
        CharSequence userText = savedState.getCharSequence("savedText");
        text.setText(userText);
    }
    @Override
    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final String name = "5";

        final TextView show = (TextView)findViewById(R.id.textView1);
        Button btn = (Button)findViewById(R.id.button1);
        btn.setOnClickListener(new View.OnClickListener() 
        {

            public void onClick(View v) 
            {
                // TODO Auto-generated method stub

                show.setText(name);

            }
        });
    }
}

---

一个被忽视但严重的错误。 必须首先将数据传递给onSavedInstanceState（）并调用onSavedInstanceState（）。如果您这样想，您会发现在传递要保存的数据之前调用savedinstancestate是无用的。它不会将活动实例保存为之前调用的onSavedInstanceState（）。。 它应该是：

@Override
protected void onSaveInstanceState(Bundle SavedInstanceState) 
{           
    SavedInstanceState.putInt("salavat-count", a);
    super.onSaveInstanceState(SavedInstanceState); 
}

---

认真地这可能是我见过的最糟糕的格式化代码了…@AlexLockwood我知道我要编辑和整理，但后来我觉得。。。H@Alexlockwood：D.u.r是的，因为我是安卓系统的新手。这很有帮助。这能回答你的问题吗？这不是一个解决方案，而是重新启动方向的一个解决方案。您的活动可以在许多事件中重新启动，更改方向只是其中之一。广泛且公开建议避免这种做法，因为随着android的发展，它甚至不再是一种解决方法。如果我们在更新textview文本时使用不同的文本颜色。我们怎样才能把它保存下来呢？你能帮我吗？

<activity android:name="package.subpackage.xptoactivity" android:configChanges="orientation"></activity>

public class MainActivity extends Activity 
{

    protected void onSaveInstanceState(Bundle outState) 
    {
        super.onSaveInstanceState(outState);
        System.out.println("TAG, onSavedInstanceState");

        final TextView text = (TextView)findViewById(R.id.textView1);
        CharSequence userText = text.getText();
        outState.putCharSequence("savedText", userText);
    }
    protected void onRestoreInstanceState(Bundle savedState) 
    {       
        System.out.println("TAG, onRestoreInstanceState");
        final TextView text = (TextView)findViewById(R.id.textView1);
        CharSequence userText = savedState.getCharSequence("savedText");
        text.setText(userText);
    }
    @Override
    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final String name = "5";

        final TextView show = (TextView)findViewById(R.id.textView1);
        Button btn = (Button)findViewById(R.id.button1);
        btn.setOnClickListener(new View.OnClickListener() 
        {

            public void onClick(View v) 
            {
                // TODO Auto-generated method stub

                show.setText(name);

            }
        });
    }
}

@Override
protected void onSaveInstanceState(Bundle SavedInstanceState) 
{           
    SavedInstanceState.putInt("salavat-count", a);
    super.onSaveInstanceState(SavedInstanceState); 
}