Java 正在检查EditText.isEmpty()是否不工作
在我的代码中,我想检查密码字段Java 正在检查EditText.isEmpty()是否不工作,java,android,android-edittext,is-empty,Java,Android,Android Edittext,Is Empty,在我的代码中,我想检查密码字段是否为空。我正在使用isEmpty()方法来完成它,但它不起作用。将密码字段留空,将返回第二条else if语句,而不是第三条 public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.
是否为空。我正在使用isEmpty()
方法来完成它,但它不起作用。将密码
字段留空,将返回第二条else if语句,而不是第三条
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final EditText password = (EditText) findViewById(R.id.editText_Password);
Button enter = (Button) findViewById(R.id.button);
enter.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
String user_pass;
user_pass = password.getText().toString();
if (user_pass.equals("123")) {
Toast.makeText(MainActivity.this, "Welcome!", Toast.LENGTH_SHORT).show();
Intent I = new Intent("com.mavenmaverick.password.OKActivity");
startActivity(I);
}
else
if(user_pass != "123"){
Toast.makeText(MainActivity.this, "Incorrect", Toast.LENGTH_SHORT).show();
AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(MainActivity.this);
dialogBuilder.setIcon(R.drawable.ic_launcher);
dialogBuilder.setTitle("Oops!");
dialogBuilder.setMessage("Incorrect Password");
dialogBuilder.setPositiveButton("OK", null);
dialogBuilder.show();
}
else
if (user_pass.isEmpty()) {
AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(MainActivity.this);
dialogBuilder.setIcon(R.drawable.ic_launcher);
dialogBuilder.setTitle("Oops!");
dialogBuilder.setMessage("Password Field Cannot Be Empty");
dialogBuilder.setPositiveButton("OK", null);
dialogBuilder.show();
}
}
});
}
您的第二个if检查user\u pass!=“123”
。从逻辑上讲,如果用户通行证
为空,它就不是“123”
,甚至第三个if也不会出现。如果你想让它工作,请切换第二个和第三个
if (string == "aString") {
...
} else if (string != "somestring") {
...
} else if (string.isEmpty()) {
...
}
这不会检查字符串是否为空,它将在第二个if块停止,因为它不相等
要避免这种情况,请先检查它是否为空。另外,在比较字符串值时,不要使用=
:
if (user_pass.isEmpty()) {
// It's empty
} else if (user_pass.equals("123")) {
// Equals
} else if (!user_pass.equals("123")){
// Not equals
}
与运算符的字符串比较错误。对于字符串比较,可以使用.equals()
方法
顺便说一下你的案子
就用,
if (user_pass.isEmpty()) {
displayAlertDialog("Password Field Cannot Be Empty");
}else if(user_pass.equals("123"))
{
Toast.makeText(MainActivity.this, "Welcome!", Toast.LENGTH_SHORT).show();
Intent I = new Intent("com.mavenmaverick.password.OKActivity");
startActivity(I);
}else
{
Toast.makeText(MainActivity.this, "Incorrect", Toast.LENGTH_SHORT).show();
displayAlertDialog("Incorrect Password");
}
private void displayAlertDialog(String message)
{
AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(MainActivity.this);
dialogBuilder.setIcon(R.drawable.ic_launcher);
dialogBuilder.setTitle("Oops!");
dialogBuilder.setMessage(message);
dialogBuilder.setPositiveButton("OK", null);
dialogBuilder.show();
}
如果(用户通过!=“123”){
您直接检查的是记忆位置,该位置始终为假
如果(!user\u pass.equals(“123”){而不是。user\u pass!=“123”
不正确,则使用。它必须是!user\u pass.equals(“123”)