Android Spinner 验证
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Android Spinner validation
提问by Golia
I need to validate selected itemof Spinnerin Android.
我需要验证所选项目的Spinner在Android。
I tried the following code, but it's not working.
我尝试了以下代码，但它不起作用。
if (Spinner1.getSelectedItem().toString().trim() == "Pick one") {
Toast.makeText(CallWs.this, "Error", Toast.LENGTH_SHORT).show();
}
What is wrong with the code, and how can i fix it?
代码有什么问题，我该如何解决？
回答by Chirag Ghori
Use .equalsor .equalsIgnoreCaseto compare two strings in java/androidinstead of ==.
使用.equals或.equalsIgnoreCase来比较两个字符串java/android而不是==。
Try this
尝试这个
if (Spinner1.getSelectedItem().toString().trim().equals("Pick one")) {
Toast.makeText(CallWs.this, "Error", Toast.LENGTH_SHORT).show();
}
回答by Darush
Create a new layout called spinner_item.xml:
创建一个名为 spinner_item.xml 的新布局：
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:gravity="center_vertical"
android:layout_width="match_parent"
android:layout_height="match_parent" />
inside your activity MainActivity.java initialize your spinner view:
在您的活动 MainActivity.java 中初始化您的微调视图：
Spinner mySpinner= (Spinner) findViewById(R.id.mySpinner);
ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this, R.array.items_array, R.layout.spinner_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
mySpinner.setAdapter(adapter);
Finally use the following method to validate your spinner:
最后使用以下方法来验证您的微调器：
boolean validateSpinner(Spinner spinner, String error){
View selectedView = spinner.getSelectedView();
if (selectedView != null && selectedView instanceof TextView) {
TextView selectedTextView = (TextView) selectedView;
if (selectedTextView.getText().equals("")) {
selectedTextView.setError(error);
Toast.makeText(this, error, Toast.LENGTH_LONG).show();
return false;
}
}
return true;
}
回答by Saro Ta?ciyan
Use equals("Pick one")and always use equals()method when checking for equalityfor Stringtype in Java(unless you are checking for referenceequality) as follows;
使用equals("Pick one")始终使用equals()检查方法时，平等的String在类型的Java（除非你检查参考平等）如下：
if (Spinner1.getSelectedItem().toString().trim().equals("Pick one")) {
Toast.makeText(CallWs.this, "Error", Toast.LENGTH_SHORT).show();
}
What's wrong with you code is; you are using ==which results in checking if Spinner1.getSelectedItem().toString()is the same referenceas "Pick one"which will always be false since "Pick one" is a new String()instance
你的代码有什么问题；您正在使用==其结果在检查是否Spinner1.getSelectedItem().toString()是相同的参考因为"Pick one"这将永远是假的，因为“选择一个”是一个new String()实例
For details, check:
有关详细信息，请检查：
回答by Piyush
Simply use this.
简单地使用这个。
else if (Spinner1.getSelectedItem().toString().trim().equalsIgnoreCase("Pick one")) {
Toast.makeText(CallWs.this, "Error",
Toast.LENGTH_SHORT).show();
回答by ESAVITHRI BE 2013 CSE
boolean validateSpinner(Spinner spinner, String error){
View selectedView = spinner.getSelectedView();
if (selectedView != null && selectedView instanceof TextView) {
TextView selectedTextView = (TextView) selectedView;
if (selectedTextView.getText().equals("Select Academic Year")) {
selectedTextView.setError(error);
Toast.makeText(this, error, Toast.LENGTH_LONG).show();
return false;
}
}
return true;
}
回答by Hariharan
Try this..
尝试这个..
else if (Spinner1.getSelectedItem().toString().trim().equals("Pick one")) {
Toast.makeText(CallWs.this, "Error",
Toast.LENGTH_SHORT).show();
==always just compares two references(for non-primitives, that is) - i.e. it tests whether the two operands refer to the same object.
==总是只比较两个引用（对于非原语，即） - 即它测试两个操作数是否引用同一个对象。
However, the equalsmethod can be overridden - so two distinct objects can still be equal...... For more info
但是，该equals方法可以被覆盖 - 因此两个不同的对象仍然可以相等...... 更多信息
