关于android context 空指针 问题

自定义对话框不是这么搞啊

MyDialog.java
 package com.antex.assist;

import android.app.Dialog;
import android.content.Context;
import android.content.DialogInterface;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
import android.widget.TextView;

import com.antex.R;

/**
 * <h3>package:</h3> com.antex.assist <br>
 * <h3>file:</h3> MyDialog.java <br>
 * 
 * <h3>Description:自定义dialog</h3><br>
 * <h3>创建时间：</h3>2013-10
 * 
 * 
 * <pre>
 * @author xiaosanyu<br>
 * &nbsp;&nbsp;email: 446251495@qq.com<br>
 * &nbsp;&nbsp;blog:  <a href="http://blog.csdn.net/a87b01c14">http://blog.csdn.net/a87b01c14</a>
 * </pre>
 * 
 */

public class MyDialog extends Dialog {

    /**
     * 构造函数
     * 
     * @param context
     *            上下文环境
     * @param theme
     *            主题
     */
    public MyDialog(Context context, int theme) {
        super(context, theme);
    }

    /**
     * 构造函数
     * 
     * @param context
     *            上下文环境
     */
    public MyDialog(Context context) {
        super(context);
    }

    /**
     * Helper class for creating a custom dialog
     */
    public static class Builder {
        /** 上下文环境 */
        private Context context;
        /** 标题 */
        private String title;
        /** 消息内容 */
        private String message;
        /** 左侧按钮文字 */
        private String positiveButtonText;
        /** 右侧按钮文字 */
        private String negativeButtonText;
        /** 中间按钮文字 */
        private String neutralButtonText;
        /** 子视图 */
        private View contentView;
        /** 标题图标 */
        private int titleimg = 0;

        /** 左侧按钮点击监听 */
        private DialogInterface.OnClickListener positiveButtonClickListener;
        /** 中间按钮点击监听 */

        private DialogInterface.OnClickListener neutralButtonClickListener;
        /** 右侧按钮点击监听 */
        private DialogInterface.OnClickListener negativeButtonClickListener;

        /**
         * 构造器
         * 
         * @param context
         *            上下文环境
         */
        public Builder(Context context) {
            this.context = context;
        }

        /**
         * Set the Dialog message from String
         * 
         * @param message
         *            String类型对话框消息
         * @return Builder 是个抽象类。用于抽象创建下属dialog等类
         */
        public Builder setMessage(String message) {
            this.message = message;
            return this;
        }

        /**
         * Set the Dialog message from resource
         * 
         * @param message
         *            int型根据ID获取会话框消息
         * @return Builder 是个抽象类。用于抽象创建下属dialog等类
         */
        public Builder setMessage(int message) {
            this.message = (String) context.getText(message);
            return this;
        }

        /**
         * Set the Dialog title from resource
         * 
         * @param title
         *            int型根据ID获取对话框标题
         * @return Builder 是个抽象类。用于抽象创建下属dialog等类
         */
        public Builder setTitle(int title) {
            this.title = (String) context.getText(title);
            return this;
        }

        /**
         * Set the Dialog titleimg from resource
         * 
         * @param titleimg
         *            对话框图标
         * @return Builder 是个抽象类。用于抽象创建下属dialog等类
         */
        public Builder setIcon(int titleimg) {
            this.titleimg = titleimg;
            return this;
        }

        /**
         * Set the Dialog title from String
         * 
         * @param title
         *            String型对话框标题
         * @return Builder 是个抽象类。用于抽象创建下属dialog等类
         */
        public Builder setTitle(String title) {
            this.title = title;
            return this;
        }

        /**
         * Set a custom content view for the Dialog. If a message is set, the
         * contentView is not added to the Dialog...
         * 
         * @param v
         *            对话框子视图
         * @return Builer 是个抽象类。用于抽象创建下属dialog等类
         */
        public Builder setContentView(View v) {
            this.contentView = v;
            return this;
        }

        /**
         * Set the positive button resource and it's listener
         * 
         * @param positiveButtonText
         *            按钮文本
         * @param listener
         *            按钮点击监听
         * @return Builer 是个抽象类。用于抽象创建下属dialog等类
         */
        public Builder setPositiveButton(int positiveButtonText,
                DialogInterface.OnClickListener listener) {
            this.positiveButtonText = (String) context
                    .getText(positiveButtonText);
            this.positiveButtonClickListener = listener;
            return this;
        }

        /**
         * Set the positive button text and it's listener
         * 
         * @param positiveButtonText
         *            按钮文本
         * @param listener
         *            按钮点击监听
         * @return Builer 是个抽象类。用于抽象创建下属dialog等类
         */
        public Builder setPositiveButton(String positiveButtonText,
                DialogInterface.OnClickListener listener) {
            this.positiveButtonText = positiveButtonText;
            this.positiveButtonClickListener = listener;
            return this;
        }

        /**
         * Set the negative button resource and it's listener
         * 
         * @param negativeButtonText
         *            按钮文本
         * @param listener
         *            按钮点击监听
         * @return Builer 是个抽象类。用于抽象创建下属dialog等类
         */
        public Builder setNegativeButton(int negativeButtonText,
                DialogInterface.OnClickListener listener) {
            this.negativeButtonText = (String) context
                    .getText(negativeButtonText);
            this.negativeButtonClickListener = listener;
            return this;
        }

        /**
         * Set the negative button text and it's listener
         * 
         * @param negativeButtonText
         *            按钮文本
         * @param listener
         *            按钮点击监听
         * @return Builer 是个抽象类。用于抽象创建下属dialog等类
         */
        public Builder setNegativeButton(String negativeButtonText,
                DialogInterface.OnClickListener listener) {
            this.negativeButtonText = negativeButtonText;
            this.negativeButtonClickListener = listener;
            return this;
        }

        /**
         * Set the Neutral button resource and it's listener
         * 
         * @param neutralButtonText
         *            按钮文本
         * @param listener
         *            按钮点击监听
         * @return Builer 是个抽象类。用于抽象创建下属dialog等类
         */
        public Builder setNeutralButton(int neutralButtonText,
                DialogInterface.OnClickListener listener) {
            this.neutralButtonText = (String) context
                    .getText(neutralButtonText);
            this.negativeButtonClickListener = listener;
            return this;
        }

        /**
         * Set the Neutral button text and it's listener
         * 
         * @param neutralButtonText
         *            按钮文本
         * @param listener
         *            按钮点击监听
         * @return Builer 是个抽象类。用于抽象创建下属dialog等类
         */
        public Builder setNeutralButton(String neutralButtonText,
                DialogInterface.OnClickListener listener) {
            this.neutralButtonText = neutralButtonText;
            this.neutralButtonClickListener = listener;
            return this;
        }

        /**
         * Create the custom dialog
         * 
         * @return MyDialog 返回自定义Dialog
         */
        public MyDialog create() {
            LayoutInflater inflater = (LayoutInflater) context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            // instantiate the dialog with the custom Theme
            final MyDialog dialog = new MyDialog(context, R.style.MyDialog);
            View layout = inflater.inflate(R.layout.dialog, new LinearLayout(
                    context), false);
            ImageView titleimage = (ImageView) layout
                    .findViewById(R.id.dialog_title_image);
            TextView tv = (TextView) layout.findViewById(R.id.dialog_msg);
            Button positiveButton = (Button) layout
                    .findViewById(R.id.positiveButton);
            Button negativeButton = (Button) layout
                    .findViewById(R.id.negativeButton);
            Button neutralButton = (Button) layout
                    .findViewById(R.id.neutralButton);
            dialog.addContentView(layout, new LayoutParams(
                    LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT));
            // set the dialog title
            if (title != null)
                ((TextView) layout.findViewById(R.id.dialog_title))
                        .setText(title);
            if (titleimg != 0)
                titleimage.setBackgroundResource(titleimg);
            else
                titleimage.setVisibility(View.GONE);
            // set the confirm button
            if (positiveButtonText != null) {
                positiveButton.setText(positiveButtonText);
                if (positiveButtonClickListener != null) {
                    positiveButton
                            .setOnClickListener(new View.OnClickListener() {
                                @Override
                                public void onClick(View v) {
                                    positiveButtonClickListener.onClick(dialog,
                                            DialogInterface.BUTTON_POSITIVE);
                                }
                            });
                }
            } else {
                // if no confirm button just set the visibility to GONE
                positiveButton.setVisibility(View.GONE);
            }
            // set the cancel button
            if (negativeButtonText != null) {
                negativeButton.setText(negativeButtonText);
                if (negativeButtonClickListener != null) {
                    negativeButton
                            .setOnClickListener(new View.OnClickListener() {
                                @Override
                                public void onClick(View v) {
                                    negativeButtonClickListener.onClick(dialog,
                                            DialogInterface.BUTTON_POSITIVE);
                                }
                            });
                }
            } else {
                // if no confirm button just set the visibility to GONE
                negativeButton.setVisibility(View.GONE);
            }

            // set the neutral button
            if (neutralButtonText != null) {
                neutralButton.setText(neutralButtonText);
                LayoutParams lp = positiveButton.getLayoutParams();
                lp.width = convertDIP2PX(80);
                positiveButton.setLayoutParams(lp);
                RelativeLayout.LayoutParams contentLayoutParams = new RelativeLayout.LayoutParams(
                        convertDIP2PX(80),
                        RelativeLayout.LayoutParams.WRAP_CONTENT);
                contentLayoutParams.leftMargin = convertDIP2PX(15);
                contentLayoutParams.addRule(RelativeLayout.RIGHT_OF,
                        R.id.neutralButton);
                negativeButton.setLayoutParams(contentLayoutParams);
                if (neutralButtonClickListener != null) {
                    neutralButton
                            .setOnClickListener(new View.OnClickListener() {
                                @Override
                                public void onClick(View v) {
                                    neutralButtonClickListener.onClick(dialog,
                                            DialogInterface.BUTTON_POSITIVE);
                                }
                            });
                }
            } else {
                // if no neutral button just set the visibility to GONE
                neutralButton.setVisibility(View.GONE);
            }
            // set the content message
            if (message != null) {
                tv.setText(message);
            }
            if (contentView != null) {
                // add the contentView to the dialog body
                if (message == null || message == "")
                    tv.setVisibility(View.GONE);
                LinearLayout ll = (LinearLayout) layout
                        .findViewById(R.id.content);
                // WindowManager manager = (WindowManager) context
                // .getSystemService(Context.WINDOW_SERVICE);
                // Display display = manager.getDefaultDisplay();
                // int width = display.getWidth();
                LinearLayout.LayoutParams contentLayoutParams = new LinearLayout.LayoutParams(
                        LinearLayout.LayoutParams.MATCH_PARENT,
                        LinearLayout.LayoutParams.WRAP_CONTENT);
                contentLayoutParams.weight = 0;
                // contentLayoutParams.gravity=Gravity.CENTER_VERTICAL;
                contentLayoutParams.leftMargin = 30;
                contentLayoutParams.rightMargin = 30;
                contentLayoutParams.topMargin = 10;
                ll.addView(contentView, contentLayoutParams);
            }
            dialog.setContentView(layout);
            return dialog;
        }

        /**
         * 转换dip为px
         * 
         * @param dip
         *            dip大小
         * @return int dip单位转换成px大小
         */
        public int convertDIP2PX(int dip) {
            float scale = context.getResources().getDisplayMetrics().density;
            return (int) (dip * scale + 0.5f);
        }
    }
}

布局文件

dialog.xml
 <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="@drawable/dialog_bg"
    android:gravity="center_horizontal"
    android:orientation="vertical" >

    <RelativeLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:paddingLeft="20dip" >

        <ImageView
            android:id="@+id/dialog_title_image"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="15dip"
            android:layout_marginTop="15dip"
            android:background="@drawable/dialog_title_image"
            android:contentDescription="@string/button_back" />

        <TextView
            android:id="@+id/dialog_title"
            style="@style/DialogText.Title"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="19dp"
            android:layout_marginTop="20dip"
            android:layout_toRightOf="@+id/dialog_title_image" />
    </RelativeLayout>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="1dip"
        android:layout_marginLeft="10dip"
        android:layout_marginRight="10dip"
        android:layout_marginTop="5dip"
        android:background="@drawable/lins" />

    <ScrollView
        android:layout_width="fill_parent"
        android:layout_height="0dip"
        android:layout_weight="1"
        android:fillViewport="true" >

        <LinearLayout
            android:id="@+id/content"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical" >

            <TextView
                android:id="@+id/dialog_msg"
                style="@style/DialogText"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_marginLeft="15dip"
                android:layout_marginRight="5dip"
                android:layout_marginTop="10dip" />

        </LinearLayout>
    </ScrollView>

    <RelativeLayout
        android:id="@+id/drl"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:gravity="bottom|center_horizontal"
        android:paddingBottom="30dip"
        android:paddingTop="10dip" >

        <Button
            android:id="@+id/positiveButton"
            android:layout_width="100dip"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:background="@drawable/button_selector"
            android:text="@string/button_ok"
            android:textColor="@color/black"
            android:textSize="20sp"
            android:textStyle="bold" />

        <Button
            android:id="@+id/neutralButton"
            android:layout_width="80dip"
            android:layout_height="wrap_content"
            android:layout_marginLeft="15dip"
            android:layout_toRightOf="@id/positiveButton"
            android:background="@drawable/button_selector"
            android:textColor="@color/black"
            android:textSize="20sp"
            android:textStyle="bold" />

        <Button
            android:id="@+id/negativeButton"
            android:layout_width="100dip"
            android:layout_height="wrap_content"
            android:layout_marginLeft="30dip"
            android:layout_toRightOf="@id/neutralButton"
            android:background="@drawable/button_selector"
            android:text="@string/button_cancel"
            android:textColor="@color/black"
            android:textSize="20sp"
            android:textStyle="bold" />
    </RelativeLayout>

</LinearLayout>


style
  <style name="MyDialog" parent="@android:Theme.Dialog">
        <item name="android:windowFrame">@null</item>
        <item name="android:windowNoTitle">true</item>
        <item name="android:windowBackground">@drawable/dialog_bg</item>
        <item name="android:windowIsFloating">true</item>
        <item name="android:windowContentOverlay">@null</item>
    </style>

    <style name="DialogText">
        <item name="android:textColor">#FF000000</item>
        <item name="android:textSize">20sp</item>
        <item name="android:textStyle">bold</item>
    </style>

    <style name="DialogText.Title">
        <item name="android:textSize">25sp</item>
        <item name="android:textStyle">bold</item>
        <item name="android:textColor">#1E90FF</item>
    </style>

调用

            MyDialog.Builder customBuilder = new MyDialog.Builder(mContext0);
        LayoutInflater layout =getLayoutInflater();
        View longinDialogView = layout.inflate(R.layout.logindialog, null, false);

        //获取布局中的控件  
        EditText mUserName = (EditText)longinDialogView.findViewById( MResource.getIdByName(getApplication(), "id", "edit_username"));  
        EditText  mPassword = (EditText)longinDialogView.findViewById( MResource.getIdByName(getApplication(), "id", "edit_password"));  
  customBuilder.setTitle("").setContentView(view).setPositiveButton(“确定”, new
                DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.dismiss();


                    }
                }).setNegativeButton(“取消”, new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
            }
        });
        Dialog dialog = customBuilder.create();
        dialog.show();