有的时候，可能需要弹出一个对话框，以便从用户输入来获取某些确认信息。这种情况下，可以重写Activity基类中的受保护方法（protected）onCreateDialog()。
1.创建一个名为Dialog的工程。
2.main.xml中的代码。
[java]
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<Button
android:id="@+id/btn_dialog"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Click to display a dialog"
android:onClick="onClick" />
</LinearLayout>
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<Button
android:id="@+id/btn_dialog"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Click to display a dialog"
android:onClick="onClick" />
</LinearLayout>3.DialogActivity.java中的代码。
[java]
package net.horsttnann.Dialog;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;
public class DialogActivity extends Activity {
CharSequence[] items = { "Google", "Apple", "Microsoft" };
boolean[] itemsChecked = new boolean[items.length];
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
public void onClick(View v) {
showDialog(0);
}
@Override
protected Dialog onCreateDialog(int id) {
switch (id) {
case 0:
return new AlertDialog.Builder(this)
.setIcon(R.drawable.ic_launcher)
.setTitle("This is a dialog with some simple text...")
.setPositiveButton("OK",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,
int whichButton) {
Toast.makeText(getBaseContext(),
"OK clicked!", Toast.LENGTH_SHORT)
.show();
}
})
.setNegativeButton("Cancel",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,
int whichButton) {
Toast.makeText(getBaseContext(),
"Cancel clicked!",
Toast.LENGTH_SHORT).show();
}
})
.setMultiChoiceItems(items, itemsChecked,
new DialogInterface.OnMultiChoiceClickListener() {
public void onClick(DialogInterface dialog,
int which, boolean isChecked) {
Toast.makeText(
getBaseContext(),
items[which]
+ (isChecked ? " checked!"
: " unchecked!"),
Toast.LENGTH_SHORT).show();
}
}).create();
}
return null;
}
}
package net.horsttnann.Dialog;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;
public class DialogActivity extends Activity {
CharSequence[] items = { "Google", "Apple", "Microsoft" };
boolean[] itemsChecked = new boolean[items.length];
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
public void onClick(View v) {
showDialog(0);
}
@Override
protected Dialog onCreateDialog(int id) {
switch (id) {
case 0:
return new AlertDialog.Builder(this)
.setIcon(R.drawable.ic_launcher)
.setTitle("This is a dialog with some simple text...")
.setPositiveButton("OK",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,
int whichButton) {
Toast.makeText(getBaseContext(),
"OK clicked!", Toast.LENGTH_SHORT)
.show();
}
})
.setNegativeButton("Cancel",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,
int whichButton) {
Toast.makeText(getBaseContext(),
"Cancel clicked!",
Toast.LENGTH_SHORT).show();
}
})
.setMultiChoiceItems(items, itemsChecked,
new DialogInterface.OnMultiChoiceClickListener() {
public void onClick(DialogInterface dialog,
int which, boolean isChecked) {
Toast.makeText(
getBaseContext(),
items[which]
+ (isChecked ? " checked!"
: " unchecked!"),
Toast.LENGTH_SHORT).show();
}
}).create();
}
return null;
}
}
4.按F11调试。点击按钮显示对话框，在CheckBox上面打勾，就是弹出一个Toast提示，显示选中物件的文本信息。点击“OK”或“Cancel”按钮会使对话框消失。
效果图：
提示：
想要显示对话框，首先要重写Activity基类中的onCreateDialog()方法：
[java]
@Override
protected Dialog onCreateDialog(int id) {
// ...
}
@Override
protected Dialog onCreateDialog(int id) {
// ...
}
当调用showDialog()的时候，上面被重写的方法就被调用了：
[java]
public void onClick(View v) {
showDialog(0);
}
public void onClick(View v) {
showDialog(0);
}这个创建对话框的onCreateDialog()方法是一个被Activity控制的回调函数，当调用showDialog()时，onCreateDialog()回调函数就被触发了。showDialog()方法接受一个Integer参数，用来识别到底要显示哪个对话框。一般情况下，使用switch语句去判断显示不同的对话框。
想要创建一个对话框，还需要使用AlertDialog类的Builder构造器，设置不同的属性，比如图标、标题、按钮、单选框等等：
[java]
@Override
protected Dialog onCreateDialog(int id) {
switch (id) {
case 0:
Builder builder = new AlertDialog.Builder(this);
builder.setIcon(R.drawable.ic_launcher);
builder.setTitle("This is a dialog with some simple text...");
builder.setPositiveButton("OK",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,
int whichButton) {
Toast.makeText(getBaseContext(), "OK clicked!",
Toast.LENGTH_SHORT).show();
}
});
builder.setNegativeButton("Cancel",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,
int whichButton) {
Toast.makeText(getBaseContext(), "Cancel clicked!",
Toast.LENGTH_SHORT).show();
}
});
builder.setMultiChoiceItems(items, itemsChecked,
new DialogInterface.OnMultiChoiceClickListener() {
public void onClick(DialogInterface dialog, int which,
boolean isChecked) {
Toast.makeText(
getBaseContext(),
items[which]
+ (isChecked ? " checked!"
: " unchecked!"),
Toast.LENGTH_SHORT).show();
}
});
return builder.create();
}
return null;
}
摘自horsttnann
