我有一个情况，有两个领域。Field1和field2。我想要的
当field1被改变时，要做的是空field2，反之亦然。所以只有在最后
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("");
}
});
它工作得很好，如果我附加addTextChangedListener到field1，但当
我对两个字段都这么做，应用程序崩溃了。显然是因为他们想要改变
无限地相互联系。一旦field1改变，此时它就会清除field2
Field2被更改，因此它将清除field1，以此类推……
谁能给点建议吗?
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基本上是被收回的参数，它被放入缩进中或通过缩进传递。
Intent intent = getIntent();
noteid = intent.getIntExtra("noteid", -1);
下面的代码基本上是额外的代码，如果你想更清楚地理解的话。
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->rightclick->
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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NoteEditor.java用于编辑目的，我的应用程序基本上是笔记应用程序。
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) {
}
});
}
}
另一个可能会帮助别人的解决方案。有2个EditText，它们在编辑后相互改变。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。我是一个开发新手
您可以添加一个检查，只在字段中的文本不为空时清除(即当长度不等于0时)。
field1.addTextChangedListener(new TextWatcher() {
@Override
public void afterTextChanged(Editable s) {}
@Override
public void beforeTextChanged(CharSequence s, int start,
int count, int after) {
}
@Override
public void onTextChanged(CharSequence s, int start,
int before, int count) {
if(s.length() != 0)
field2.setText("");
}
});
field2.addTextChangedListener(new TextWatcher() {
@Override
public void afterTextChanged(Editable s) {}
@Override
public void beforeTextChanged(CharSequence s, int start,
int count, int after) {
}
@Override
public void onTextChanged(CharSequence s, int start,
int before, int count) {
if(s.length() != 0)
field1.setText("");
}
});
这里是TextWatcher的文档。
另外，请尊重命名约定。
我们可以在编辑文本之前删除字段的TextWatcher，然后在编辑文本之后将其添加回来。
将field1和field2的文本监视器声明为单独的变量，并为它们命名:例如field1
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) {
}
};
然后使用它的名称添加该监视程序:
field1. addtextchangedlistener (Field_1_Watcher)用于field1，和
field2. addtextchangedlistener (Field_2_Watcher)用于field2
在修改field2文本之前，删除TextWatcher:
field2.removeTextChangedListener (Field_2_Watcher)
修改文本:
field2.setText (" ")
然后将TextWatcher添加回来:
field2.addTextChangedListener (Field_2_Watcher)
对另一个字段做同样的处理
