http://blog.sina.com.cn/s/blog_474928c90100x871.html
public class Ex04_1Activity extends Activity {
EditText editText;
TextView textView;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
editText = (EditText) findViewById(R.id.myEditText);
textView = (TextView) findViewById(R.id.myTextView);
editText.setOnKeyListener(new OnKeyListener() {
@Override
public boolean onKey(View arg0, int arg1, KeyEvent arg2) {
textView.setText(editText.getText());
Toast toast = new Toast(Ex04_1Activity.this);
toast.setView(textView);//错误1
toast.show();
return false;
}
});
}
}
错误1的地方会报view not attached to windows manager的错误。根据错误提示，将代码改为如下就可行了：
@Override
public boolean onKey(View arg0, int arg1, KeyEvent arg2) {
textView.setText(editText.getText());
Toast toast = new Toast(Ex04_1Activity.this);
TextView textView1 = new TextView(Ex04_1Activity.this);
textView1.setText(textView.getText());
toast.setView(textView1);
toast.show();
return false;
}
由此分析，以findViewById形式生成的View，new Toast()这种方式是拿不到的，因为初始程序还会报告一个FindViewLocked的错误。
为了进一步证明我的猜想，将代码改成如下形式：
public boolean onKey(View arg0, int arg1, KeyEvent arg2) {
textView.setText(editText.getText());
Toast.makeText(Ex04_1Activity.this, editText.getText(), 1).show();
return false;
}
程序又一次通过了。
再次改一下代码：
public boolean onKey(View arg0, int arg1, KeyEvent arg2) {
textView.setText(editText.getText());
Toast toast = new Toast(Ex04_1Activity.this);
toast.setText(editText.getText().toString());
toast.show();
return false;
}
这时又报了一个：This Toast was not created with Toast.makeText()的错误。
由此可见，Toast.makeText()生成的Toast可以访问findViewById方式生成的View，而自己New Toast()的方式生成的Toast只能访问同样new 出来的View对象。原因大概是在.xml中生成的View对象可以被多个Activity引用，Android为了安全起见，就将其上了锁，并且提供唯一的Toast方式，Toast.makeText()来实现吐丝，这一点和单例模式颇有共同之处
view not attached to windows manager与This Toast was not created with Toast.makeText()