Android setOnClickListener方法可以';无法获取编辑文本值
环境:Android Studio 3.1.1Android setOnClickListener方法可以';无法获取编辑文本值,android,oncreate,Android,Oncreate,环境:Android Studio 3.1.1 public class AddQuestionActivity extends AppCompatActivity { public Button add_question; public EditText question_EditText; @Override protected void onCreate(Bundle savedInstanceState) { super.onCr
public class AddQuestionActivity extends AppCompatActivity
{
public Button add_question;
public EditText question_EditText;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add_question);
add_question = findViewById(R.id.addquestion);
question_EditText = findViewById(R.id.question_add);
final String question = question_EditText.getText().toString();
Log.d("finds","question1:"+question);
add_question.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
Log.d("finds","question:"+question);
if (question.length()==0)
{
new AlertDialog.Builder(AddQuestionActivity.this)
.setTitle(R.string.add_error)
.setMessage(R.string.add_blank)
.setPositiveButton(R.string.ok, null)
.setNeutralButton(R.string.cancel, null)
.show();
}
}
});
}
}
问题的值总是空的
最后,我找到了另一种方法
在*.xml中添加
android:onClick="add_question"
在*.java中使用
public void add_question(View v)
{
}
它是有效的
我不明白为什么setOnClickListener方法不起作用
final String question = question_EditText.getText().toString();
我应该将此代码更改为setOnClickListener方法吗?试试这个
注意:如果您试图将edittext值从onclick中取出,它将始终在onclick中
final String question=question_EditText.getText().toString()代码>
去掉这个
final String question = question_EditText.getText().toString();
在初始活动时,它仅获得1次值
MoveString question=question_EditText.getText().toString()将>编码到onClick方法中
final String question = question_EditText.getText().toString();
Log.d("finds","question1:"+question);
单击按钮时,尝试此操作以获取edittext中的当前字符串
添加_question.setOnClickListener(新视图.OnClickListener()
{
@凌驾
公共void onClick(视图v)
{
String question=question_EditText.getText().toString();
日志d(“发现”,“问题:+问题”);
if(question.length()=0)
{
新建AlertDialog.Builder(AddQuestionActivity.this)
.setTitle(R.string.add_错误)
.setMessage(R.string.add_blank)
.setPositiveButton(R.string.ok,null)
.setNeutralButton(R.string.cancel,null)
.show();
}
}
});代码>
这行代码在OnCreate()方法中,因此在加载活动时只调用一次。
将文本添加到EditText后,单击按钮,但字符串“question”仅包含初始值;不是最新的。
所以,您应该在将文本添加到EditText.or按钮的onClick listener之后调用该代码
String question = question_EditText.getText().toString();
将这行放在onClick()
你用
final String question = question_EditText.getText().toString();
改为
String question = uestion_EditText.getText().toString(); //gets you the question of edit text
将这一行放在onClick()中。
像这样:
add_question.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
String question = question_EditText.getText().toString();
Log.d("finds","question:"+question);
if (question.length()==0)
{
new AlertDialog.Builder(AddQuestionActivity.this)
.setTitle(R.string.add_error)
.setMessage(R.string.add_blank)
.setPositiveButton(R.string.ok, null)
.setNeutralButton(R.string.cancel, null)
.show();
}
}
});
}
}
从那里删除以下行并将其添加到onclick方法中
final String question = question_EditText.getText().toString();
Log.d("finds","question1:"+question);
这里是onCreate()
方法的完整代码
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add_question);
add_question = findViewById(R.id.addquestion);
question_EditText = findViewById(R.id.question_add);
add_question.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
final String question = question_EditText.getText().toString();
Log.d("finds","question1:"+question);
if (question.length()==0)
{
new AlertDialog.Builder(AddQuestionActivity.this)
.setTitle(R.string.add_error)
.setMessage(R.string.add_blank)
.setPositiveButton(R.string.ok, null)
.setNeutralButton(R.string.cancel, null)
.show();
}
}
});
}
为什么不在点击时把问题串放进去呢!它是空的,因为当你的活动打开时,问题字符串获取编辑文本的值,你想要编辑文本的最新值,所以你应该检查onClick内的长度,并获取onClick内编辑文本的文本内容回答:Rahul Chandrabhan:我是android新手,有时会犯愚蠢的错误,每个人都有…甚至我…哈哈
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add_question);
add_question = findViewById(R.id.addquestion);
question_EditText = findViewById(R.id.question_add);
add_question.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
final String question = question_EditText.getText().toString();
Log.d("finds","question1:"+question);
if (question.length()==0)
{
new AlertDialog.Builder(AddQuestionActivity.this)
.setTitle(R.string.add_error)
.setMessage(R.string.add_blank)
.setPositiveButton(R.string.ok, null)
.setNeutralButton(R.string.cancel, null)
.show();
}
}
});
}