我正在使用活动外部的自定义对话框，我已经在类中编写了对话框代码，然后在单击按钮的Activity中调用该对话框。但是这对我不起作用当我点击showDialog按钮时，应用程序崩溃了。以下是代码
活动代码
package com.Customers;
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.content.res.Resources.Theme;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class MainActivity extends Activity {
Context context;
int theme;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.dialog);
Button showDialog=(Button)findViewById(R.id.show_dialog);
showDialog.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Custom_Dialog calcDialog=new Custom_Dialog(context,R.style.myCoolDialog);
calcDialog.dailogCalculator();
}
});
}
}
自定义对话框类
package com.Customers;
import android.app.Dialog;
import android.content.Context;
import android.view.View;
import android.view.Window;
import android.widget.Button;
import android.widget.EditText;
public class Custom_Dialog extends Dialog implements android.view.View.OnClickListener{
Context mContext;
protected Custom_Dialog(Context context, int theme) {
super(context, theme);
}
public boolean TouchEvent(int actionOutside) {
return false;
}
public void dailogCalculator(){
Custom_Dialog alertbox = new Custom_Dialog(mContext, R.style.myCoolDialog);
alertbox.requestWindowFeature(Window.FEATURE_NO_TITLE);
alertbox.setContentView(R.layout.calculator);
EditText calcDisplay=(EditText)alertbox.findViewById(R.id.editText1);
Button value1=(Button) alertbox.findViewById(R.id.button1);
value1.setOnClickListener(this);
Button value2=(Button) alertbox.findViewById(R.id.button2);
value2.setOnClickListener(this);
Button value3=(Button) alertbox.findViewById(R.id.button3);
value3.setOnClickListener(this);
Button value4=(Button) alertbox.findViewById(R.id.button4);
value4.setOnClickListener(this);
Button value5=(Button) alertbox.findViewById(R.id.button5);
value5.setOnClickListener(this);
Button value6=(Button) alertbox.findViewById(R.id.button6);
value6.setOnClickListener(this);
Button value7=(Button) alertbox.findViewById(R.id.button7);
value7.setOnClickListener(this);
Button value8=(Button) alertbox.findViewById(R.id.button8);
value8.setOnClickListener(this);
Button value9=(Button) alertbox.findViewById(R.id.button9);
value9.setOnClickListener(this);
Button value00=(Button) alertbox.findViewById(R.id.button00);
value00.setOnClickListener(this);
Button value0=(Button) alertbox.findViewById(R.id.button0);
value0.setOnClickListener(this);
Button backspaceBtn=(Button) alertbox.findViewById(R.id.backspace);
backspaceBtn.setOnClickListener(this);
Button Ok_dialog=(Button)alertbox.findViewById(R.id.ok_dialog);
Ok_dialog.setOnClickListener(this);
Button Qty_btn=(Button)alertbox.findViewById(R.id.btn_qty);
Qty_btn.setOnClickListener(this);
alertbox.show();
}
@Override
public void onClick(View v) {
switch(v.getId()){
case R.id.button1:
break;
case R.id.button2:
break;
case R.id.button3:
break;
case R.id.button4:
break;
case R.id.button5:
break;
case R.id.button6:
break;
case R.id.button7:
break;
case R.id.button8:
break;
case R.id.button9:
break;
case R.id.button0:
break;
case R.id.button00:
break;
case R.id.backspace:
break;
case R.id.btn_qty:
break;
case R.id.ok_dialog:
break;
}
}
}
Logcat
03-04 16:54:47.293: E/AndroidRuntime(275): at java.lang.reflect.Method.invokeNative(Native Method)
03-04 17:16:22.793: E/AndroidRuntime(332): FATAL EXCEPTION: main
03-04 17:16:22.793: E/AndroidRuntime(332): java.lang.NullPointerException
03-04 17:16:22.793: E/AndroidRuntime(332): at android.app.Dialog.<init>(Dialog.java:141)
03-04 17:16:22.793: E/AndroidRuntime(332): at com.Customers.Custom_Dialog.<init>(Custom_Dialog.java:13)
03-04 17:16:22.793: E/AndroidRuntime(332): at com.Customers.MainActivity$1.onClick(MainActivity.java:24)
03-04 17:16:22.793: E/AndroidRuntime(332): at android.view.View.performClick(View.java:2408)
03-04 17:16:22.793: E/AndroidRuntime(332): at android.view.View$PerformClick.run(View.java:8816)
03-04 17:16:22.793: E/AndroidRuntime(332): at android.os.Handler.handleCallback(Handler.java:587)
03-04 17:16:22.793: E/AndroidRuntime(332): at android.os.Handler.dispatchMessage(Handler.java:92)
03-04 17:16:22.793: E/AndroidRuntime(332): at android.os.Looper.loop(Looper.java:123)
03-04 17:16:22.793: E/AndroidRuntime(332): at android.app.ActivityThread.main(ActivityThread.java:4627)
03-04 17:16:22.793: E/AndroidRuntime(332): at java.lang.reflect.Method.invokeNative(Native Method)
03-04 17:16:22.793: E/AndroidRuntime(332): at java.lang.reflect.Method.invoke(Method.java:521)
03-04 17:16:22.793: E/AndroidRuntime(332): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
03-04 17:16:22.793: E/AndroidRuntime(332): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
03-04 17:16:22.793: E/AndroidRuntime(332): at dalvik.system.NativeStart.main(Native Method)
请指导我做错的地方。它也真的有助于其他人。
答案 0 :(得分：1)
将Custom_Dialog构造函数更改为：
Context mContext;
protected Custom_Dialog(Context context, int theme) {
super(context, theme);
this.mContext=context; //<<<<<< initialize mContext here
}
以及MainActivity内部onCreate使用活动上下文初始化context，然后将其传递给Custom_Dialog构造函数：
//......your code here
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.dialog);
context=MainActivity.this //<<<<< initialize context here
//......your code here
答案 1 :(得分：1)
您没有在构造函数中实例化上下文mContext。问题似乎就在那里。
答案 2 :(得分：1)
试试这种方式。它会解决它。
public class MainActivity extends Activity {
Context context;
int theme;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.dialog);
context= this;
Button showDialog=(Button)findViewById(R.id.show_dialog);
showDialog.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Custom_Dialog calcDialog=new Custom_Dialog(context,R.style.myCoolDialog);
calcDialog.show();
}
});
}
}
自定义Dialog.java
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.calculator);
EditText calcDisplay=(EditText)findViewById(R.id.editText1);
Button value1=(Button) findViewById(R.id.button1);
value1.setOnClickListener(this);
Button value2=(Button) findViewById(R.id.button2);
value2.setOnClickListener(this);
.......
}
答案 3 :(得分：0)
这不是我认为的正确方法。您必须使用“主题”对话框创建活动并调用此活动。该活动应该看起来像一个对话框。
<activity android:theme="@android:style/Theme.Dialog" />
答案 4 :(得分：0)
您必须在像这个
这样的单独类中创建对话框 Custom_Dialog alertbox = new Custom_Dialog(currentActivity);
currentActivity是当前的活动参考。
稍后
LayoutInflater layoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
因此，您必须为其他类传递上下文和当前活动引用。