android studio

Question

安卓studio实现登录功能 我单独开一个项目时可以登陆成功然后跳转到主页面，但是放在整个项目里就无法跳转 会闪退

Answer 1

看看你放到新项目里面的AndroidManifest.xml清单文件有没有注册对应的登录Activity

Answer 2

//MainActivitypackage com.example.a.movie;import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;import butterknife.ButterKnife;
import fragment.menufragment;
public class MainActivity extends AppCompatActivity {    public static final String MAIN_CONTENT_TAG = "main_content_tag";    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
//        设置主页面
        setContentView(R.layout.activity_main);
        ButterKnife.bind(this);
//        初始化fragment
        initFragment();    }    private void initFragment() {
//        得到fragment
        FragmentManager fm = getSupportFragmentManager();
//        开启事务
        FragmentTransaction ft = fm.beginTransaction();
//        替换
        ft.replace(R.id.f1_main_content,new menufragment(),MAIN_CONTENT_TAG);  //主页
//        提交
        ft.commit();
    }
}
//RegisterActivitypackage com.example.a.movie;import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.text.TextUtils;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
import android.widget.Toast;
import db.DBOpenHelper;
import butterknife.BindView;
import butterknife.ButterKnife;
import butterknife.OnClick;/**
 * Created by littlecurl 2018/6/24
 */
public class RegisterActivity extends AppCompatActivity{    private String realCode;
    private DBOpenHelper mDBOpenHelper;    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_register);
        ButterKnife.bind(this);
        mDBOpenHelper = new DBOpenHelper(this);        //将验证码用图片的形式显示出来
        mIvRegisteractivityShowcode.setImageBitmap(Code.getInstance().createBitmap());
        realCode = Code.getInstance().getCode().toLowerCase();
    }    @BindView(R.id.rl_registeractivity_top)
    RelativeLayout mRlRegisteractivityTop;
    @BindView(R.id.iv_registeractivity_back)
    ImageView mIvRegisteractivityBack;
    @BindView(R.id.ll_registeractivity_body)
    LinearLayout mLlRegisteractivityBody;
    @BindView(R.id.et_registeractivity_username)
    EditText mEtRegisteractivityUsername;
    @BindView(R.id.et_registeractivity_password1)
    EditText mEtRegisteractivityPassword1;
    @BindView(R.id.et_registeractivity_password2)
    EditText mEtRegisteractivityPassword2;
    @BindView(R.id.et_registeractivity_phoneCodes)
    EditText mEtRegisteractivityPhonecodes;
    @BindView(R.id.iv_registeractivity_showCode)
    ImageView mIvRegisteractivityShowcode;
    @BindView(R.id.rl_registeractivity_bottom)
    RelativeLayout mRlRegisteractivityBottom;    /**
     * 注册页面能点击的就三个地方
     * top处返回箭头、刷新验证码图片、注册按钮
     */
    @OnClick({
            R.id.iv_registeractivity_back,
            R.id.iv_registeractivity_showCode,
            R.id.bt_registeractivity_register
    })
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.iv_registeractivity_back: //返回登录页面
                Intent intent1 = new Intent(this, loginActivity.class);
                startActivity(intent1);
                finish();
                break;
            case R.id.iv_registeractivity_showCode:    //改变随机验证码的生成
                mIvRegisteractivityShowcode.setImageBitmap(Code.getInstance().createBitmap());
                realCode = Code.getInstance().getCode().toLowerCase();
                break;
            case R.id.bt_registeractivity_register:    //注册按钮
                //获取用户输入的用户名、密码、验证码
                String username = mEtRegisteractivityUsername.getText().toString().trim();
                String password = mEtRegisteractivityPassword2.getText().toString().trim();
                String phoneCode = mEtRegisteractivityPhonecodes.getText().toString().toLowerCase();
                //注册验证
                if (!TextUtils.isEmpty(username) && !TextUtils.isEmpty(password) && !TextUtils.isEmpty(phoneCode) ) {
                    if (phoneCode.equals(realCode)) {
                        //将用户名和密码加入到数据库中
                        mDBOpenHelper.add(username, password);
                        Intent intent2 = new Intent(this, MainActivity.class);
                        startActivity(intent2);
                        finish();
                        Toast.makeText(this,  "验证通过，注册成功", Toast.LENGTH_SHORT).show();
                    } else {
                        Toast.makeText(this, "验证码错误,注册失败", Toast.LENGTH_SHORT).show();
                    }
                }else {
                    Toast.makeText(this, "未完善信息，注册失败", Toast.LENGTH_SHORT).show();
                }
                break;
        }
    }
}

Answer 3

日志贴出来，查看日志见新手博客：https://blog.csdn.net/weimingjue/article/details/87921494