我的android登录应用不幸停止
我的简单应用程序不幸停止错误。我的android登录应用不幸停止,android,login-script,Android,Login Script,我的简单应用程序不幸停止错误。 请解决这个问题 我不需要任何权限 以下是我的android主要活动: package vk.com.login_simple; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.*; public clas
请解决这个问题 我不需要任何权限 以下是我的android主要活动:
package vk.com.login_simple;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.*;
public class MainActivity extends AppCompatActivity {
private EditText username=(EditText) findViewById(R.id.username);
private EditText password=(EditText) findViewById(R.id.password);
private Button login=(Button) findViewById(R.id.login);
private Button reset=(Button) findViewById(R.id.reset);
private Button exit=(Button) findViewById(R.id.exit);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setTitle("Login App");
setContentView(R.layout.activity_main);
}
public void login(View view){
if(username.getText().toString().equals("admin")&&password.getText().toString().equals("password")){
Toast.makeText(getApplicationContext(),"Login Success",Toast.LENGTH_LONG).show();
//your code here
}else{
Toast.makeText(getApplicationContext(),"Wrong Username / Password",Toast.LENGTH_LONG).show();
}
}
public void reset(View view) {
username.setText("");
password.setText("");
Toast.makeText(this,"Reset success",Toast.LENGTH_LONG).show();
}
public void exit(){
//empty
}
}
在onCreate()方法中创建findViewById之后,可以使用它们。将解析放在onCreate()方法中
findViewById
仅在定义布局根视图的setContentView()
之后工作,以显示可以找到视图的位置。如果你在Android之外打电话,你不知道如何以及在哪里为你找到视图
因此,您必须做的是将所有findViewById()
代码放在onCreate()
中,并放在setContentView()之后
解析onCreate方法内部
public class MainActivity extends AppCompatActivity {
private EditText username;
private EditText password;
private Button login;
private Button reset;
private Button exit;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setTitle("Login App");
setContentView(R.layout.activity_main);
username=(EditText) findViewById(R.id.username);
password=(EditText) findViewById(R.id.password);
login=(Button) findViewById(R.id.login);
reset=(Button) findViewById(R.id.reset);
exit=(Button) findViewById(R.id.exit);
}
}
而不是解析使用
您必须在onCreate方法内部初始化,如belllow
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
EditText username=(EditText) findViewById(R.id.username);
EditText password=(EditText) findViewById(R.id.password);
Button login=(Button) findViewById(R.id.login);
Button reset=(Button) findViewById(R.id.reset);
Button exit=(Button) findViewById(R.id.exit);
}
请显示logcat和logcat输出您能给出activity_main.xml吗请为logcat添加activity_main.xml
private EditText username;
private EditText password;
private Button login;
private Button reset;
private Button exit;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setTitle("Login App");
username=(EditText) findViewById(R.id.username);
password=(EditText) findViewById(R.id.password);
login=(Button) findViewById(R.id.login);
reset=(Button) findViewById(R.id.reset);
exit=(Button) findViewById(R.id.exit);
}
public class MainActivity extends AppCompatActivity {
private EditText username;
private EditText password;
private Button login;
private Button reset;
private Button exit;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setTitle("Login App");
setContentView(R.layout.activity_main);
username=(EditText) findViewById(R.id.username);
password=(EditText) findViewById(R.id.password);
login=(Button) findViewById(R.id.login);
reset=(Button) findViewById(R.id.reset);
exit=(Button) findViewById(R.id.exit);
}
}
public class MainActivity extends AppCompatActivity {
@BindView(R.id.username)
private EditText username;
@BindView(R.id.password)
private EditText password;
@BindView(R.id.login)
private Button login;
@BindView(R.id.reset)
private Button reset;
@BindView(R.id.exit)
private Button exit;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setTitle("Login App");
setContentView(R.layout.activity_main);
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
EditText username=(EditText) findViewById(R.id.username);
EditText password=(EditText) findViewById(R.id.password);
Button login=(Button) findViewById(R.id.login);
Button reset=(Button) findViewById(R.id.reset);
Button exit=(Button) findViewById(R.id.exit);
}