Java android上的文本更改侦听器
我有一种情况,有两个领域<代码>字段1和Java android上的文本更改侦听器,java,android,textview,onchange,Java,Android,Textview,Onchange,我有一种情况,有两个领域字段1和字段2。我想要的一切 更改field1时,待办事项为空field2,反之亦然。所以最后才 一个字段上有内容 field1 = (EditText)findViewById(R.id.field1); field2 = (EditText)findViewById(R.id.field2); field1.addTextChangedListener(new TextWatcher() { public void afterTextChanged(Edit
字段2
。我想要的一切
更改field1
时,待办事项为空field2
,反之亦然。所以最后才
一个字段上有内容
field1 = (EditText)findViewById(R.id.field1);
field2 = (EditText)findViewById(R.id.field2);
field1.addTextChangedListener(new TextWatcher() {
public void afterTextChanged(Editable s) {}
public void beforeTextChanged(CharSequence s, int start,
int count, int after) {
}
public void onTextChanged(CharSequence s, int start,
int before, int count) {
field2.setText("");
}
});
field2.addTextChangedListener(new TextWatcher() {
public void afterTextChanged(Editable s) {}
public void beforeTextChanged(CharSequence s, int start,
int count, int after) {
}
public void onTextChanged(CharSequence s, int start,
int before, int count) {
field1.setText("");
}
});
如果我只将addTextChangedListener
附加到field1
上,它可以正常工作,但是
我在应用程序崩溃的两个领域都这么做。显然是因为他们试图改变
彼此无限期地相互依赖。一旦field1
发生更改,此时将清除field2
field2
已更改,因此它将清除field1
,依此类推
有人能提出解决方案吗?只有当字段中的文本不为空时(即当长度不同于0时),才可以添加复选框以清除
TextWatcher的文档
另外,请尊重。在将另一个
EditText
设置为空之前检查字符串。如果Field1
为空,那么为什么需要再次更改为(“”)?因此,您可以使用s.lenght()或任何其他解决方案检查字符串的大小
检查字符串长度的另一种方法是:
String sUsername = Field1.getText().toString();
if (!sUsername.matches(""))
{
// do your job
}
我也遇到了同样的问题,并不断得到
stackOverflow
异常,我提供了以下解决方案
edt_amnt_sent.addTextChangedListener(new TextWatcher() {
@Override
public void afterTextChanged(Editable s) {
if (skipOnChange)
return;
skipOnChange = true;
try {
//method
} catch (NumberFormatException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
skipOnChange = false;
}
}
});
edt_amnt_receive.addTextChangedListener(new TextWatcher() {
@Override
public void afterTextChanged(Editable s) {
if (skipOnChange)
return;
skipOnChange = true;
try {
//method
} catch (NumberFormatException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
skipOnChange = false;
}
}
});
声明的初始布尔值skipOnChange=false 您还可以使用hasFocus()方法:
在我正在做的一项大学作业中测试了这一点,在用户输入时转换温标。它工作得很好,而且更简单。我知道这很旧,但有一天可能会有人再次遇到它 我遇到了一个类似的问题,我会在EditText上调用setText,而在我不想调用的时候会调用ContextChanged。我的第一个解决方案是在调用setText()后编写一些代码,以撤销侦听器造成的损坏。但那不是很优雅。 在做了一些研究和测试之后,我发现使用getText().clear()清除文本的方式与setText(“”)清除文本的方式大致相同,但由于它没有设置文本,因此不会调用侦听器,因此解决了我的问题。我将所有setText(“”)调用都切换到getText().clear(),我不再需要绷带了,所以也许这也能解决您的问题 试试这个:
Field1 = (EditText)findViewById(R.id.field1);
Field2 = (EditText)findViewById(R.id.field2);
Field1.addTextChangedListener(new TextWatcher() {
public void afterTextChanged(Editable s) {}
public void beforeTextChanged(CharSequence s, int start,
int count, int after) {
}
public void onTextChanged(CharSequence s, int start,
int before, int count) {
Field2.getText().clear();
}
});
Field2.addTextChangedListener(new TextWatcher() {
public void afterTextChanged(Editable s) {}
public void beforeTextChanged(CharSequence s, int start,
int count, int after) {
}
public void onTextChanged(CharSequence s, int start,
int before, int count) {
Field1.getText().clear();
}
});
回答有点晚,但这里有一个可重用的解决方案:
/**
* An extension of TextWatcher which stops further callbacks being called as
* a result of a change happening within the callbacks themselves.
*/
public abstract class EditableTextWatcher implements TextWatcher {
private boolean editing;
@Override
public final void beforeTextChanged(CharSequence s, int start,
int count, int after) {
if (editing)
return;
editing = true;
try {
beforeTextChange(s, start, count, after);
} finally {
editing = false;
}
}
protected abstract void beforeTextChange(CharSequence s, int start,
int count, int after);
@Override
public final void onTextChanged(CharSequence s, int start,
int before, int count) {
if (editing)
return;
editing = true;
try {
onTextChange(s, start, before, count);
} finally {
editing = false;
}
}
protected abstract void onTextChange(CharSequence s, int start,
int before, int count);
@Override
public final void afterTextChanged(Editable s) {
if (editing)
return;
editing = true;
try {
afterTextChange(s);
} finally {
editing = false;
}
}
public boolean isEditing() {
return editing;
}
protected abstract void afterTextChange(Editable s);
}
因此,当使用上述方法时,TextWatcher中发生的任何setText()
调用都不会导致再次调用TextWatcher:
/**
* A setText() call in any of the callbacks below will not result in TextWatcher being
* called again.
*/
public class MyTextWatcher extends EditableTextWatcher {
@Override
protected void beforeTextChange(CharSequence s, int start, int count, int after) {
}
@Override
protected void onTextChange(CharSequence s, int start, int before, int count) {
}
@Override
protected void afterTextChange(Editable s) {
}
}
如果您使用Kotlin进行Android开发,则可以使用以下代码添加
TextChangedListener()
:
myTextField.addTextChangedListener(object : TextWatcher{
override fun afterTextChanged(s: Editable?) {}
override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {}
override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {}
})
我为此编写了自己的扩展,对我很有帮助。(科特林) 你只能这样写:
editText.customAfterTextChanged { editable ->
//You have accessed the editable object.
}
我的分机号码:
fun EditText.customAfterTextChanged(action: (Editable?)-> Unit){
this.addTextChangedListener(object : TextWatcher {
override fun beforeTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {}
override fun onTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {}
override fun afterTextChanged(editable: Editable?) {
action(editable)
}
})}
在
onCreate
方法中动态添加背景:
getWindow().setBackgroundDrawableResource(R.drawable.background);
还要从XML中删除背景
editText.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
}
@Override
public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
if (noteid != -1) {
MainActivity.notes.set(noteid, String.valueOf(charSequence));
MainActivity.arrayAdapter.notifyDataSetChanged();
}
}
@Override
public void afterTextChanged(Editable editable) {
}
});
在这段代码中,noteid基本上是收回的参数,这些参数被放入缩进或通过缩进传递
Intent intent = getIntent();
noteid = intent.getIntExtra("noteid", -1);
如果您想更清楚地理解,下面的代码基本上是额外的代码。
how to make the menu or insert the menu in our code ,
create the menu folder this the folder created by going into the raw
->rightclick->
directory->name the folder as you wish->
then click on the directory formed->
then click on new file and then name for file as you wish ie the folder name file
and now type the 2 lines code in it and see the magic.
新的活动代码命名为noteditor.java。出于编辑目的,我的应用程序基本上就是note应用程序
package com.example.elavi.notes;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.widget.EditText;
import android.widget.Toast;
import static android.media.CamcorderProfile.get;
public class NoteEditorActivity extends AppCompatActivity {
EditText editText;
int noteid;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_note_editor);
editText = findViewById(R.id.editText);
Intent intent = getIntent();
noteid = intent.getIntExtra("noteid", -1);
if (noteid != -1) {
String text = MainActivity.notes.get(noteid);
editText.setText(text);
Toast.makeText(getApplicationContext(),"The arraylist content is"+MainActivity.notes.get(noteid),Toast.LENGTH_SHORT).show();
}
else
{
Toast.makeText(getApplicationContext(),"Here we go",Toast.LENGTH_SHORT).show();
MainActivity.notes.add("");
noteid=MainActivity.notes.size()-1;
}
editText.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
}
@Override
public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
if (noteid != -1) {
MainActivity.notes.set(noteid, String.valueOf(charSequence));
MainActivity.arrayAdapter.notifyDataSetChanged();
}
}
@Override
public void afterTextChanged(Editable editable) {
}
});
}
}
在Kotlin中,只需使用KTX扩展功能即可: (它使用
TextWatcher
)
导入核心KTX:
implementation "androidx.core:core-ktx:1.2.0"
我们可以在编辑文本之前删除字段的TextWatcher,然后在编辑文本后将其添加回 将field1和field2的文本监视程序声明为单独的变量,为它们命名:例如,field1 然后使用其名称添加观察者:
field1.addTextChangedListener(Field\u 1\u Watcher)
用于field1,以及
field2.addTextChangedListener(Field\u 2\u Watcher)
用于field2
更改field2文本之前,请删除TextWatcher:
field2.removeTextChangedListener(Field\u 2\u Watcher)
更改文本:
field2.setText(“”)
然后重新添加TextWatcher:
field2.addTextChangedListener(字段观察者)
对另一个字段执行相同的操作另一个可能有帮助的解决方案。有两个EditText,编辑后会相互替换。默认情况下,它导致了周期性 使用变量:
Boolean uahEdited = false;
Boolean usdEdited = false;
添加TextWatcher
uahEdit = findViewById(R.id.uahEdit);
usdEdit = findViewById(R.id.usdEdit);
uahEdit.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
if (!usdEdited) {
uahEdited = true;
}
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
String tmp = uahEdit.getText().toString();
if(!tmp.isEmpty() && uahEdited) {
uah = Double.valueOf(tmp);
usd = uah / 27;
usdEdit.setText(String.valueOf(usd));
} else if (tmp.isEmpty()) {
usdEdit.getText().clear();
}
}
@Override
public void afterTextChanged(Editable s) {
uahEdited = false;
}
});
usdEdit.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
if (!uahEdited) {
usdEdited = true;
}
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
String tmp = usdEdit.getText().toString();
if (!tmp.isEmpty() && usdEdited) {
usd = Double.valueOf(tmp);
uah = usd * 27;
uahEdit.setText(String.valueOf(uah));
} else if (tmp.isEmpty()) {
uahEdit.getText().clear();
}
}
@Override
public void afterTextChanged(Editable s) {
usdEdited = false;
}
});
不要批评太多。我是一名新手开发人员当用户输入editText.setText时,该如何处理?EditText在这种情况下有重点,这是最好的解决方案。“堆栈已满”我想你指的是堆栈溢出;)如何在所有字段更改后进行检测,因为在按下任何按钮时,它会在每次更改时进行检测。对于新用户,请使用可观察的字符串字段进行双向数据绑定,因为此处提供的所有解决方案可能会产生
开始等待阻止gc alloc
这类错误,甚至可能导致崩溃和挂起。。所以选择数据绑定,这是安全的,谷歌现在推荐的。很好。这么干净
var filenameText = findViewById(R.id.filename) as EditText
filenameText.addTextChangedListener(object : TextWatcher {
override fun afterTextChanged(s: Editable?) {
filename = filenameText.text.toString()
Log.i("FileName: ", filename)
}
override fun beforeTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {}
override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {}
})
private TextWatcher Field_1_Watcher = new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
@Override
public void afterTextChanged(Editable s) {
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
}
};
Boolean uahEdited = false;
Boolean usdEdited = false;
uahEdit = findViewById(R.id.uahEdit);
usdEdit = findViewById(R.id.usdEdit);
uahEdit.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
if (!usdEdited) {
uahEdited = true;
}
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
String tmp = uahEdit.getText().toString();
if(!tmp.isEmpty() && uahEdited) {
uah = Double.valueOf(tmp);
usd = uah / 27;
usdEdit.setText(String.valueOf(usd));
} else if (tmp.isEmpty()) {
usdEdit.getText().clear();
}
}
@Override
public void afterTextChanged(Editable s) {
uahEdited = false;
}
});
usdEdit.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
if (!uahEdited) {
usdEdited = true;
}
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
String tmp = usdEdit.getText().toString();
if (!tmp.isEmpty() && usdEdited) {
usd = Double.valueOf(tmp);
uah = usd * 27;
uahEdit.setText(String.valueOf(uah));
} else if (tmp.isEmpty()) {
uahEdit.getText().clear();
}
}
@Override
public void afterTextChanged(Editable s) {
usdEdited = false;
}
});
var filenameText = findViewById(R.id.filename) as EditText
filenameText.addTextChangedListener(object : TextWatcher {
override fun afterTextChanged(s: Editable?) {
filename = filenameText.text.toString()
Log.i("FileName: ", filename)
}
override fun beforeTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {}
override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {}
})