Java 按钮单击导致空指针
每次我点击按钮,应用程序就会崩溃。我很难找到这个bug,但我确信它与onClickListener或onClick函数有关 注意:我正在使用解析API处理一些后端内容。但我高度怀疑它与任何解析内容都有任何关系 我的代码是这样的:Java 按钮单击导致空指针,java,android,parse-platform,Java,Android,Parse Platform,每次我点击按钮,应用程序就会崩溃。我很难找到这个bug,但我确信它与onClickListener或onClick函数有关 注意:我正在使用解析API处理一些后端内容。但我高度怀疑它与任何解析内容都有任何关系 我的代码是这样的: public class SignUpActivity extends Activity { protected EditText mUserName; protected EditText mPassword; protected EditT
public class SignUpActivity extends Activity {
protected EditText mUserName;
protected EditText mPassword;
protected EditText mEmail;
protected Button mSignUpButton;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
setContentView(R.layout.activity_sign_up);
mUserName = (EditText) findViewById(R.id.usernameField);
mPassword = (EditText) findViewById(R.id.passwordField);
mEmail = (EditText) findViewById(R.id.emailField);
mSignUpButton = (Button) findViewById(R.id.signupButton);
mSignUpButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String username = mUserName.getText().toString();
String password = mPassword.getText().toString();
String email = mEmail.getText().toString();
username = username.trim();
password = password.trim();
email = email.trim();
if(username.isEmpty() || password.isEmpty() || email.isEmpty()){
AlertDialog.Builder builder = new AlertDialog.Builder(SignUpActivity.this);
builder.setMessage(R.string.signup_error_message)
.setTitle(R.string.signup_error_title)
.setPositiveButton(android.R.string.ok, null);
AlertDialog dialog = builder.create();
dialog.show();
}
else{
setProgressBarIndeterminateVisibility(true);
ParseUser newUser = new ParseUser();
newUser.setUsername(username);
newUser.setPassword(password);
newUser.setEmail(email);
newUser.signUpInBackground(new SignUpCallback() {
@Override
public void done(ParseException e) {
setProgressBarIndeterminateVisibility(false);
if(e == null){
// success
Intent intent = new Intent(SignUpActivity.this, MainActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(intent);
}
else{
AlertDialog.Builder builder = new AlertDialog.Builder(SignUpActivity.this);
builder.setMessage(e.getMessage())
.setTitle(R.string.signup_error_title)
.setPositiveButton(android.R.string.ok, null);
AlertDialog dialog = builder.create();
dialog.show();
}
}
});
}
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.sign_up, menu);
return true;
}
}
这是我的原木猫:
04-14 14:19:05.881: E/AndroidRuntime(1156): FATAL EXCEPTION: main 04-14 14:19:05.881:
E/AndroidRuntime(1156): Process: com.ebad.ribbit, PID: 1156 04-14 14:19:05.881:
E/AndroidRuntime(1156): java.lang.NullPointerException 04-14 14:19:05.881:
E/AndroidRuntime(1156): at com.ebad.ribbit.SignUpActivity$1.onClick(SignUpActivity.java:40) 04-14 14:19:05.881:
E/AndroidRuntime(1156): at android.view.View.performClick(View.java:4438) 04-14 14:19:05.881:
E/AndroidRuntime(1156): at android.view.View$PerformClick.run(View.java:18422) 04-14 14:19:05.881:
E/AndroidRuntime(1156): at android.os.Handler.handleCallback(Handler.java:733) 04-14 14:19:05.881:
E/AndroidRuntime(1156): at android.os.Handler.dispatchMessage(Handler.java:95) 04-14 14:19:05.881:
E/AndroidRuntime(1156): at android.os.Looper.loop(Looper.java:136) 04-14 14:19:05.881:
E/AndroidRuntime(1156): at android.app.ActivityThread.main(ActivityThread.java:5017) 04-14 14:19:05.881:
E/AndroidRuntime(1156): at java.lang.reflect.Method.invokeNative(Native Method) 04-14 14:19:05.881:
E/AndroidRuntime(1156): at java.lang.reflect.Method.invoke(Method.java:515) 04-14 14:19:05.881:
E/AndroidRuntime(1156): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 04-14 14:19:05.881:
E/AndroidRuntime(1156): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 04-14 14:19:05.881:
E/AndroidRuntime(1156): at dalvik.system.NativeStart.main(Native Method)
编辑:
根据要求,以下是第40行:
String username = mUserName.getText().toString();
编辑2:
下面是添加log.i(标记,mUserName==null?“mUserName为null”:mUserName.getText()==null?“mUserName.getText()为null):“无任何内容为null”)代码>:
04-14 15:21:47.955: E/AndroidRuntime(1318): FATAL EXCEPTION: main
04-14 15:21:47.955: E/AndroidRuntime(1318): Process: com.ebad.ribbit, PID: 1318
04-14 15:21:47.955: E/AndroidRuntime(1318): java.lang.NullPointerException
04-14 15:21:47.955: E/AndroidRuntime(1318): at com.ebad.ribbit.SignUpActivity$1.onClick(SignUpActivity.java:43)
04-14 15:21:47.955: E/AndroidRuntime(1318): at android.view.View.performClick(View.java:4438)
04-14 15:21:47.955: E/AndroidRuntime(1318): at android.view.View$PerformClick.run(View.java:18422)
04-14 15:21:47.955: E/AndroidRuntime(1318): at android.os.Handler.handleCallback(Handler.java:733)
04-14 15:21:47.955: E/AndroidRuntime(1318): at android.os.Handler.dispatchMessage(Handler.java:95)
04-14 15:21:47.955: E/AndroidRuntime(1318): at android.os.Looper.loop(Looper.java:136)
04-14 15:21:47.955: E/AndroidRuntime(1318): at android.app.ActivityThread.main(ActivityThread.java:5017)
04-14 15:21:47.955: E/AndroidRuntime(1318): at java.lang.reflect.Method.invokeNative(Native Method)
04-14 15:21:47.955: E/AndroidRuntime(1318): at java.lang.reflect.Method.invoke(Method.java:515)
04-14 15:21:47.955: E/AndroidRuntime(1318): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-14 15:21:47.955: E/AndroidRuntime(1318): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-14 15:21:47.955: E/AndroidRuntime(1318): at dalvik.system.NativeStart.main(Native Method)
编辑3:
根据要求,以下是我的activity\u sign\u.xml:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".SignUpActivity" >
<EditText
android:id="@+id/userNameField"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:hint="@string/username_hint"
android:ems="10" >
<requestFocus />
</EditText>
<EditText
android:id="@+id/passwordField"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@+id/userNameField"
android:ems="10"
android:hint="@string/password_hint"
android:inputType="textPassword" />
<EditText
android:id="@+id/emailField"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@+id/passwordField"
android:ems="10"
android:hint="@string/email_hint"
android:inputType="textEmailAddress" />
<Button
android:id="@+id/signupButton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/emailField"
android:layout_below="@+id/emailField"
android:layout_marginTop="50dp"
android:text="@string/sign_up_button_label" />
</RelativeLayout>
如果mUsername
为null
,对其调用getText()
将导致NullPointerException
。在执行此操作之前,应该检查它是否不为null。尝试更改为以下内容:
if(mUserName == null || mPassword == null || mEmail == null){
AlertDialog.Builder builder = new AlertDialog.Builder(SignUpActivity.this);
builder.setMessage(R.string.signup_error_message)
.setTitle(R.string.signup_error_title)
.setPositiveButton(android.R.string.ok, null);
AlertDialog dialog = builder.create();
dialog.show();
}
String username = mUserName.getText().toString();
String password = mPassword.getText().toString();
String email = mEmail.getText().toString();
username = username.trim();
password = password.trim();
email = email.trim();
试一试
还要确保在应用程序清单中声明了SignUpActivity。我想应该确保所有活动都已在清单中设置
编辑1
如果第40行是问题所在,那么
mUserName为空
或
mUserName.getText()为空。因此,在手之前创建一些检查,并添加一些调试日志,以验证它们是否为null
确保R.layout.activity\u注册时将usernameField作为id。同时确保在任何其他app/res/layout文件夹(即layout-v14)中,所有R.layout.activity\u注册时也包含edittext。如果第40行出现此错误,则表示您的edittext将变为null
String username = String.valueOf(mUserName.getText());
String password = String.valueOf(mPassword.getText());
String email = String.valueOf(mEmail.getText());
在每一个你得到字符串的地方尝试它。至少它可以避免您从EditText获取空指针异常
String username = String.valueOf(mUserName.getText());
String password = String.valueOf(mPassword.getText());
String email = String.valueOf(mEmail.getText());
请这样做:
@Override
public void onClick(View v) {
if(mUserName != null && mPassword != null && mEmail != null && mUserName.getText() != null && mPassword.getText() != null && mEmail.getText() != null)
{
Your original code here.
}
}
更新:
打字错误
mUserName=(EditText)findViewById(R.id.usernameField);应该是userNameField吗?
SignUpActivity.java的第40行请发布SignUpActivity.java的第40行。然后你能把-------Log.i(TAG,mUserName==null?“mUserName为null”:mUserName.getText()==null?“mUserName.getText()为null”:“无任何内容为null”)代码>------------在第39行?那么你能在我的代码运行的异常之前发布日志吗?哈哈,这根本没有意义,你有没有隐藏信息日志或其他什么?你知道吗?将其更改为Log.e,以防Log.i被隐藏。我没有将它们保留为null。我仍然有同样的错误。在根据你的建议更改代码后,它仍然崩溃。注意:我不是让字段为空,我是在输入值。我同意您应该在编写代码之前检查空值。但是,我不认为您当前的问题是由于edittext。您是否也可以上传您的activity\u sign\u up.xml文件。哇,当我点击注册按钮时,什么都没有发生。什么都不喜欢,甚至连撞车都不喜欢。这正是我所期望的。这是因为其中至少有一个是空的代码>为什么usernameField不是usernameField<代码>我想这可能是问题所在,让我想想。它很有效。哇,真不敢相信我竟然没有看到这个打字错误,比如小错误造成了这么大的头痛。请留下答案或编辑您的旧答案,以便我选择。
mUserName = (EditText) findViewById(R.id.usernameField); should be userNameField?
<EditText android:id="@+id/userNameField" ...