Question

尝试登录后我的应用程序崩溃了。我创建navigationActivity为 CHome ，我希望我的用户可以定向到。但它一直在崩溃：

不幸的是，您的应用已停止工作。

但是当我在下方禁用此行时，它会显示Toast而不会崩溃。

请帮助

Toast.makeText(LoginActivity.this, "CUSTOMER",Toast.LENGTH_SHORT).show();

Intent cHome = new Intent(LoginActivity.this, CHome.class);
Common.currentUser = user;
startActivity(cHome);
finish();

我在这里有我的清单

我的CHome如下

package com.example.oracle.eliteafro;

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.view.View;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;

//import com.example.oracle.eliteafro.Common.Common;
//import com.google.firebase.database.DatabaseReference;
//import com.google.firebase.database.FirebaseDatabase;

public class CHome extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener {

    //Init Firebase
    //FirebaseDatabase database;
    //    DatabaseReference salons;

  TextView loginName;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_chome);


        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        toolbar.setTitle("Menu");
        setSupportActionBar(toolbar);



        //Init Firebase
       // database = FirebaseDatabase.getInstance();
        //salons = database.getReference("el_af_salon");



        FloatingActionButton fab = (FloatingActionButton) 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 = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.setDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);


        //set name for user
        View headerView = navigationView.getHeaderView(0);
        loginName = (TextView) findViewById(R.id.loginName);
        loginName.setText("Beedy");
        //loginName.setText(Common.currentUser.getFullname());

    }

    @Override
    public void onBackPressed() {
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.chome, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @SuppressWarnings("StatementWithEmptyBody")
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        // Handle navigation view item clicks here.
        //int id = item.getItemId();

//        if (id == R.id.nav_camera) {
//            // Handle the camera action
//        } else if (id == R.id.nav_gallery) {
//
//        } else if (id == R.id.nav_slideshow) {
//
//        } else if (id == R.id.nav_manage) {
//
//        } else if (id == R.id.nav_share) {
//
//        } else if (id == R.id.nav_send) {
//
//        }

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);
        return true;
    }
}

Answer 1

将CHome声明为AndroidManifest.xml中的活动

<强>更新

我看到了您更新的问题，因此问题在于您的CHome活动，在设置文本之前，您没有获得TextView的引用。

TextView yourTextView = findViewById(R.id.your_text_view_id);
yourTextView.setText("your text");

更新2

好的，我认为你需要传递参数，你可以使用额外的参数传递参数。

Intent cHome = new Intent(LoginActivity.this, CHome.class);
cHome.putExtra("user", user);
startActivity(cHome);
finish();

然后在您的CHome活动课上，你需要收到额外的费用：

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.yourlayout);
        User user = (User)  getIntent().getSerializableExtra("user");
        //now you can use your user object
       TextView yourTextView = findViewById(R.id.your_text_view_id);
       yourTextView.setText(user.getName()); // for example
    }

不要忘记您的User类必须实现Serializable

Answer 2

问题出在你的onCreate方法的CHome中，你引用了一个null TextView。所以要么你忘记打电话了

TextView textView = findViewById(R.id.your_text_view_id);

或者，也许您确实调用了该方法，但是您将id传递给了布局中不存在的视图，因为findViewById将以静默方式失败并返回null而不是通过异常。因此，当您在TextView上调用setText（）时，您将获得NullPointerexception。

应用程序在使用Intent时崩溃

2 个答案: