代码不报错 xml 没报错 却在手机上运行不了单个activity可以互相作为主activity打开 却不能互相跳转

Question

XueShengYuYueActivity.java
package cn.jxufe.timetable;

import android.app.Activity;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;

public class XueShengYuYueActivity extends Activity {
    private SQLiteDatabase database;
    private String databaseFilename = Environment
            .getExternalStorageDirectory() + "/timetable/timetable.db";
    int z;
    @Override
    protected void onCreate(Bundle saveInstanceState){
        super.onCreate(saveInstanceState);
        setContentView(R.layout.activity_xueshengyuyue);
        database = SQLiteDatabase.openOrCreateDatabase(databaseFilename, null);
        final EditText xuehao=(EditText)findViewById(R.id.xuehao);
        final Button chaxun=(Button)findViewById(R.id.chaxun);
        final ListView lv=(ListView)findViewById(R.id.lv);
        chaxun.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View view){
                if(xuehao.getText().toString().isEmpty()){
                    Toast.makeText(XueShengYuYueActivity.this,"请输入学号",Toast.LENGTH_SHORT).show();
                    return;
                }
                Cursor cursor= database.query("t_all",new String[]{"place","course","week","num","stu_no"},"stu_no=?",new String[]{xuehao.getText().toString()},null,null,null);
                if(cursor.getCount()==0){
                    Toast.makeText(XueShengYuYueActivity.this,"没有该学号的活动预约！",Toast.LENGTH_SHORT).show();
                    return;
                }
                List<String> list=new ArrayList();
                for(cursor.moveToFirst();!cursor.isAfterLast();cursor.moveToNext()){
                    list.add("预约："+cursor.getString(cursor.getColumnIndex("place"))+"，活动名称"+cursor.getString(cursor.getColumnIndex("course"))+"，时间"+cursor.getString(cursor.getColumnIndex("week"))+"，课程时间"+cursor.getString(cursor.getColumnIndex("num")));
                }
                cursor.close();
                ArrayAdapter<String> arrayAdapter=new ArrayAdapter<>(XueShengYuYueActivity.this, android.R.layout.simple_list_item_1,list);
                lv.setAdapter(arrayAdapter);
            }
        });
    }
}

activity_xueshengyuyue.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/xuehao"
        android:hint="@string/xuehao"/>
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/chaxun"
        android:text="@string/chaxun"/>
    <ListView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/lv">
    </ListView>

</LinearLayout>


```xml
AndroidManifest.xml
![img](https://img-mid.csdnimg.cn/release/static/image/mid/ask/068991365846112.JPG "#left")

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="cn.jxufe.timetable"
    android:versionCode="2"
    android:versionName="2.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="15" />

    <!-- 往sdcard中写入数据的权限 -->
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" >
    </uses-permission>
    <!-- 在sdcard中创建/删除文件的权限 -->
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" >
    </uses-permission>

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:name=".LoginActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
            <activity android:name=".AddClassActivity" />
            <activity android:name=".RoomListActivity" />
            <activity android:name=".TableActivity" />
            <activity android:name=".Table2Activity" />
            <activity android:name=".LaoShiYuYueActivity" />
            <activity android:name=".XueShengYuYueActivity" />


        </activity>


    </application>

</manifest>

Answer 1

AndroidManifest.xml发出来看看