<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"      xmlns:tools="http://schemas.android.com/tools"      android:layout_width="fill_parent"      android:layout_height="match_parent"      android:orientation="vertical"      tools:context=".MainActivity" >             <TextView          android:layout_width="wrap_content"          android:layout_height="wrap_content"          android:id="@+id/name"            android:text="姓名:"/>      <EditText android:id="@+id/editText_name"           android:layout_width="fill_parent"          android:layout_height="wrap_content"          android:hint="请输入文本信息"          />            <TextView          android:layout_width="wrap_content"          android:layout_height="wrap_content"          android:id="@+id/age"            android:text="年龄:"/>             <EditText android:id="@+id/editText_age"           android:layout_height="wrap_content"           android:layout_width="fill_parent"           android:hint="请输入年龄"/>        <Button android:id="@+id/btnSubmit"          android:layout_height="wrap_content"          android:layout_width="wrap_content"          android:text="提交验证"/>  </LinearLayout>  

package com.example.fourandroid;    import android.annotation.SuppressLint;  import android.app.Activity;  import android.app.AlertDialog;  import android.content.DialogInterface;  import android.os.Bundle;  import android.view.View;  import android.view.View.OnClickListener;  import android.widget.Button;  import android.widget.EditText;  import android.widget.Toast;    @SuppressLint("ShowToast")  public class MainActivity extends Activity {      private EditText editText_name;      private EditText editText_age;      private Button btnSubmit;            @Override      protected void onCreate(Bundle savedInstanceState) {          super.onCreate(savedInstanceState);          super.setContentView(R.layout.activity_main);                    //获取组件信息;          this.editText_name = (EditText) super.findViewById(R.id.editText_name);          this.editText_age = (EditText)super.findViewById(R.id.editText_age);                    //给按钮设置单击事件;          this.btnSubmit = (Button)super.findViewById(R.id.btnSubmit);          this.btnSubmit.setOnClickListener(new myBtnSubmitImpl());      }        public class myBtnSubmitImpl implements OnClickListener{          @Override          public void onClick(View v) {              boolean bol = true;                            String age = MainActivity.this.editText_age.getText().toString();              String name = MainActivity.this.editText_name.getText().toString();              //实例化对话框;              AlertDialog.Builder builder = new AlertDialog.Builder(v.getContext());              builder.setTitle("提示信息");                            //判断name是否为空;              if(name == null || name.trim().length() == 0 || "".equals(name.trim())){                  builder.setMessage("Name不能为空，请输入信息.");                  builder.setPositiveButton("确认", new DialogInterface.OnClickListener(){                      @Override                      public void onClick(DialogInterface dialog, int which) {                          setResult(RESULT_OK);                       }                  });                                    //设置焦点信息;                  MainActivity.this.editText_name.setFocusable(true);                  MainActivity.this.editText_name.setFocusableInTouchMode(true);                  MainActivity.this.editText_name.requestFocus();                  MainActivity.this.editText_name.requestFocusFromTouch();                  builder.show();                  //标识此文本框属性为空;                  bol = false;                  return;              }                            //判断address是否为空;              if(age == null || "".equals(age) || age.trim().length() == 0){                  builder.setMessage("Age不能为空，请输入信息.");                  //给对话框增加一个确定按钮;                  builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {                       //监听单击事件;                      public void onClick(DialogInterface dialog, int whichButton) {                           setResult(RESULT_OK);//确定按钮事件 ;                      }                   }) ;                                    //设置address焦点;                  MainActivity.this.editText_age.setFocusable(true);                  MainActivity.this.editText_age.setFocusableInTouchMode(true);                  MainActivity.this.editText_age.requestFocus();                  MainActivity.this.editText_age.requestFocusFromTouch();                                    //显示提示框;                  builder.show();                  //标识此文本框属性为空;                  bol = false;                  return;              }                            if(bol){                  //设置提示信息.                  Toast.makeText(MainActivity.this, "恭喜你,验证成功", Toast.LENGTH_LONG).show();              }          }      }  }