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在使用自定义布局时经常会碰见这样的问题：edit = (EditText) findViewById(R.id.edit);并不能获取到控件对象；

在后面代码中使用edit时会报错，空指针异常。意思是edit 为null。

解决方案：

LayoutInflater factory = LayoutInflater.from(MyDialogActivity.this);		final View view = factory.inflate(R.layout.dialog, null);		edit = (EditText) view.findViewById(R.id.edit);

MyDialogActivity.java 文件名称 MyDialogActivity.java R.layout.dialog：自定义布局文件 dialog.xml如何为Dialog布局呢？你需要定义一个布局文件，我在例子中定义了一个：dialog.xml final View view = factory.inflate(R.layout.dialog, null); 得到view，用setView(view);方法设置布局。 具体实现： dialog.xml 
   
       
    
    main.xml 
   
           
    
    MyDialogActivity.java package xiaosi.mydialog;import android.app.Activity;import android.app.AlertDialog;import android.content.DialogInterface;import android.content.DialogInterface.OnClickListener;import android.os.Bundle;import android.view.LayoutInflater;import android.view.View;import android.widget.EditText;import android.widget.TextView;public class MyDialogActivity extends Activity{	/** Called when the activity is first created. */	private EditText edit = null;    private TextView textview = null;	@Override	public void onCreate(Bundle savedInstanceState)	{		super.onCreate(savedInstanceState);		setContentView(R.layout.main);		textview = (TextView)findViewById(R.id.textView);		LayoutInflater factory = LayoutInflater.from(MyDialogActivity.this);		final View view = factory.inflate(R.layout.dialog, null);		edit = (EditText) view.findViewById(R.id.edit);		AlertDialog.Builder builder = new AlertDialog.Builder(				MyDialogActivity.this);		builder.setTitle("文字效果");		builder.setIcon(R.drawable.btn_mainmenu_words_a);		builder.setMessage("请输入你要的文字:");		builder.setView(view);		builder.setPositiveButton("提交", new SubmitListener());		builder.setNegativeButton("取消", new DismissListener());		builder.show();	}	private class SubmitListener implements OnClickListener	{		public void onClick(DialogInterface dialog, int which)		{			System.out.println(edit.getText().toString());			textview.setText("测试结果:\n" + edit.getText().toString());			dialog.dismiss();		}	}		private class DismissListener implements OnClickListener	{		public void onClick(DialogInterface dialog, int which)		{			dialog.dismiss();		}	}}

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