我已添加以下代码，因此如果在主活动中按下后退按钮，则会显示一个警告对话框，其中包含两个按钮以作出最终决定...但有时当我点击是时（一个积极的按钮来完成活动）再次显示相同的活动，而不是完成活动，我想知道我的代码中是否有任何错误......
MainActivity.java
public void onBackPressed() {
//super.onBackPressed();
Log.d("back button", "back button pressed");
AlertDialog.Builder ad1=new AlertDialog.Builder(this);
ad1.setMessage("Are you sure you want to exit? ");
ad1.setCancelable(false);
ad1.setNegativeButton("NO", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface arg0, int arg1) {
}
});
ad1.setPositiveButton("YES", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface arg0, int arg1) {
finish();
}
});
AlertDialog alert=ad1.create();
alert.show();
}
MainActivity.java完整代码
package com.vibrator;
import android.annotation.SuppressLint;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.os.Bundle;
import android.os.Vibrator;
import android.support.v7.app.ActionBar;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.CompoundButton;
import android.widget.CompoundButton.OnCheckedChangeListener;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.ToggleButton;
@SuppressLint("ShowToast")
public class MainActivity extends ActionBarActivity implements OnCheckedChangeListener, OnSeekBarChangeListener{
ToggleButton tbutton;
Vibrator v;
int i=400,j=50;
int k,l;
TextView txt;
SeekBar sb;
TextView txt1;
SeekBar sb1;
Spinner spinner1;
Button btn;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ActionBar bar = getSupportActionBar();
bar.setBackgroundDrawable(new ColorDrawable(Color.parseColor("#336699")));
//Log.e("values","i value at oncreate "+i);
//Log.e("values","i value at oncreate "+j);
//creating instance for vibrator
v=(Vibrator) getSystemService(VIBRATOR_SERVICE);
//checking if the device has vibrator or not
if(v!=null){
setContentView(R.layout.activity_main);
}
else {
setContentView(R.layout.secound);
}
//Log.e("vibrate", "setcontentview");
//creating instance of toggle buttton and setting listener
tbutton=(ToggleButton) findViewById(R.id.tb1);
tbutton.setOnCheckedChangeListener(this);
//creating instance and setting onclicklistener for the button
/*btn=(Button) findViewById(R.id.button);
btn.setOnClickListener(this);*/
sb=(SeekBar) findViewById(R.id.seekbar);
txt=(TextView) findViewById(R.id.txt12);
sb1=(SeekBar) findViewById(R.id.seekbar1);
txt1=(TextView) findViewById(R.id.txt11);
sb1.setOnSeekBarChangeListener(this);
sb.setOnSeekBarChangeListener(this);
}
@Override
public void onCheckedChanged(CompoundButton arg0, boolean arg1) {
//Log.d("real status", ""+arg1);
//if vibrator is ON
if(arg1)
{
Log.e("vibrate", "true vibrate");
// Start without a delay
// Vibrate for 100 j milliseconds
// Sleep for 1000 (i) milliseconds
Log.e("values","i value "+i);
Log.e("values","i value "+j);
long pattern[] = {0, j, i};
// The '0' here means to repeat indefinitely
// '-1' would play the vibration once
v.vibrate(pattern, 0);
}
else {
Log.e("vibrate", "false no v");
//Toast.makeText(this,"status: "+arg1, Toast.LENGTH_SHORT).show();
v.cancel();
}
}
public void onProgressChanged(SeekBar s, int v, boolean b) {
//switch statement to update values of seekbars
switch (s.getId()) {
case R.id.seekbar:
k=v;
txt.setText("Vibrator OFF time: "+k);
//Log.e("values","seekbar value "+k);
break;
case R.id.seekbar1:
l=v;
txt1.setText("Vibrator ON time: "+l);
//Log.e("values","seekbar1 value "+l);
break;
}
//seekbarchanged method implementation
if (tbutton.isChecked()) {
Log.e("values","yes tbutton is checked");
tbutton.setChecked(false);
switch (s.getId()) {
case R.id.seekbar:
i=k;
//Log.e("true", "seekbar tbutton checked "+i);
break;
case R.id.seekbar1:
j=l;
//Log.e("true", "seekbar1 tbutton checked "+j);
break;
}
Log.e("true", "set true");
tbutton.setChecked(true);
}
else{
//Toast.makeText(this,"Set ON to customize", Toast.LENGTH_SHORT).show();
AlertDialog.Builder ad=new AlertDialog.Builder(this);
ad.setTitle("Instruction");
ad.setMessage("Set the button ON to customize");
ad.setNeutralButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface arg0, int arg1) {
}
});
ad.show();
}
}
@Override
public void onStartTrackingTouch(SeekBar arg0) {
}
@Override
public void onStopTrackingTouch(SeekBar arg0) {
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflate= getMenuInflater();
inflate.inflate(R.menu.menu_v, menu);
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.menu_setting:
break;
case R.id.about:
//Toast.makeText(this, "about clicked", Toast.LENGTH_SHORT).show();
AlertDialog.Builder ad=new AlertDialog.Builder(this);
ad.setTitle("About");
ad.setMessage("This app is developed by Rajesh Uragonda");
ad.setNeutralButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface arg0, int arg1) {
}
});
ad.show();
break;
case R.id.settings:
//Toast.makeText(this, "settings clicked", Toast.LENGTH_SHORT).show();
AlertDialog.Builder ad2=new AlertDialog.Builder(this);
ad2.setTitle("Settings");
ad2.setMessage("Your settings here");
ad2.setNeutralButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface arg0, int arg1) {
}
});
ad2.show();
break;
case R.id.help:
//Toast.makeText(this, "help clicked", Toast.LENGTH_SHORT).show();
AlertDialog.Builder ad1=new AlertDialog.Builder(this);
ad1.setTitle("Help");
ad1.setMessage(R.string.alerthelp);
ad1.setNeutralButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface arg0, int arg1) {
}
});
ad1.show();
break;
}
return super.onOptionsItemSelected(item);
}
@Override
protected void onPause() {
// TODO Auto-generated method stub
super.onPause();
if (tbutton.isChecked()) {
tbutton.setChecked(false);
Log.d("onpause", "onpause mainactivity tbutton");
}
Log.d("onpause", "onpause mainactivity");
}
//responds to the button at top used as navigation to next activity
public void btn(View v){
//Button btn1=(Button) findViewById(R.id.btn1);
Intent i = new Intent(MainActivity.this, CustomPatterns.class);
startActivity(i);
}
//when back button pressed it goes directly to home
public void onBackPressed() {
//super.onBackPressed();
Log.d("back button", "back button pressed");
AlertDialog.Builder ad1=new AlertDialog.Builder(this);
ad1.setMessage("Are you sure you want to exit? ");
ad1.setCancelable(false);
ad1.setNegativeButton("NO", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface arg0, int arg1) {
}
});
ad1.setPositiveButton("YES", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface arg0, int arg1) {
MainActivity.this.finish();
}
});
AlertDialog alert=ad1.create();
alert.show();
}
}
答案 0 :(得分：1)
在您的活动中使用此代码
public void onBackPressed() {
AlertDialog diaBox = AskOption();
diaBox.show();
}
private AlertDialog AskOption()
{
AlertDialog myQuittingDialogBox =new AlertDialog.Builder(this)
.setTitle("Exit")
.setMessage("Are you sure you want to exit?")
.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
finish();
}
})
.setNegativeButton("No", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
}
})
.create();
return myQuittingDialogBox;
}
答案 1 :(得分：0)
另一种方法是将活动上下文传递给构造函数中的对话框，并使用context.finish（）完成它。
dismiss();//dismiss dialog first
context.finish();//then finish the hosting activity
答案 2 :(得分：0)
你可以在MenuItem上使用alertdialog onclick ...
只需查看下面的代码.. 谢谢
public boolean onOptionsItemSelected(MenuItem item)
{
switch (item.getItemId())
{
case R.id.menu_cgoal:
Toast.LENGTH_SHORT).show();
final EditText input = new EditText(Myclass.this);
LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.MATCH_PARENT,
LinearLayout.LayoutParams.MATCH_PARENT);
input.setLayoutParams(lp);
//input.setImeOptions(EditorInfo.IME_ACTION_DONE);
AlertDialog.Builder ad=new AlertDialog.Builder(Myclass.this);
ad.setView(input);
ad.setTitle("Create goal...");
ad.setMessage("Are you sure you want to add this goal?");
ad.setNeutralButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface arg0, int arg1) {
String value = input.getText().toString().trim();
Toast.makeText(getApplicationContext(), value, Toast.LENGTH_SHORT).show();
}
});
ad.show();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
答案 3 :(得分：-1)
不只是finish()。使用MainActivity.this.finish();