java - 什么可能导致错误
问题描述
在navigation.java中,errors:navigation已经定义在编译单元中,找不到符号方法
findNavController(Navigation ,int)
导航.java
package com.example.bcuilders;
import android.os.Bundle;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.android.material.snackbar.Snackbar;
import android.view.View;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;
import androidx.navigation.ui.AppBarConfiguration;
import androidx.navigation.ui.NavigationUI;
import com.google.android.material.navigation.NavigationView;
import androidx.drawerlayout.widget.DrawerLayout;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import android.view.Menu;
public class Navigation extends AppCompatActivity {
private AppBarConfiguration mAppBarConfiguration;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_navigation);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
DrawerLayout drawer = findViewById(R.id.drawer_layout);
NavigationView navigationView = findViewById(R.id.nav_view);
// Passing each menu ID as a set of Ids because each
// menu should be considered as top level destinations.
mAppBarConfiguration = new AppBarConfiguration.Builder(
R.id.nav_home, R.id.nav_gallery, R.id.nav_slideshow,
R.id.nav_tools, R.id.nav_share, R.id.nav_send)
.setDrawerLayout(drawer)
.build();
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
NavigationUI.setupActionBarWithNavController(this, navController, mAppBarConfiguration);
NavigationUI.setupWithNavController(navigationView, navController);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.navigation, menu);
return true;
}
@Override
public boolean onSupportNavigateUp() {
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
return NavigationUI.navigateUp(navController, mAppBarConfiguration)
|| super.onSupportNavigateUp();
}
}
并在 mainActivity.java 错误:找不到符号类意图 mainActivity.java
package com.example.bcuilders;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void buttonClick(View view)
{
EditText et1= (EditText) findViewById(R.id.MyEmail);
EditText et2= (EditText) findViewById(R.id.MyPass);
String email=et1.getText().toString();
String pass=et2.getText().toString();
String oemail="admin";
String opass="admin";
if (email.equals(oemail) && pass.equals(opass)){
Intent intent = new intent(this, Navigation.class);
startActivity(intent);
}
else{
Toast toast = Toast.makeText(this, "Invalid Email/Pass",Toast.LENGTH_LONG);
toast.show();
}
}
}
错误:导航已在编译单元中定义,在 Navigation.java 中找不到符号方法 findNavController(Navigation ,int)
解决方案
试试下面的代码:
1)在mainActivity.java中报错:找不到符号类意图mainActivity.java
而不是这个
Intent intent = new intent(this, Navigation.class);
用这个
Intent intent = new Intent(this, Navigation.class);
因为您使用的是小写意图,所以会引发该错误。
2) 在navigation.java中,errors:navigation已经在编译单元中定义,找不到符号方法findNavController(Navigation ,int)
要解决此错误,请将您navigation.java
的名称重命名为导航以外的其他名称。在您的情况下,它会尝试findNavController(Navigation, int)
在您的navigation.java
班级中找到不存在的班级。
希望能解决你的错误!!!
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