android - 寻宝 Activity 已停止

Question

当我运行该应用程序时，第一个 Activity 运行正常，但当它进入第二个 Activity 时，它说寻宝已停止运行，并且 logcat 或控制台下没有任何内容。我很确定这是 level_1.java 的问题，但无法弄清楚是什么。请帮忙谢谢。

主要 Activity :

package com.example.treasurehunt;


import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.util.Log;
import android.view.Menu;
import android.view.View;

public class MainActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
    public void Start(View view)    {
        Log.d("hi", "hello");
        Intent intent = new Intent(this, Level_1.class);
        startActivity(intent);      
        finish();
    }

}

主xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:text="Treasure Hunt" />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="82dp"
        android:text="Start"
        android:onClick="Start" />

</RelativeLayout>

`

level_1java:

package com.example.treasurehunt;

import android.os.Bundle;
import android.app.Activity;
import android.content.SharedPreferences;
import android.util.Log;
import android.view.Menu;
import android.widget.EditText;
import android.widget.TextView;

public class Level_1 extends Activity {
    private SharedPreferences settings;
    private SharedPreferences.Editor editor;
    TextView Clue = (TextView)findViewById(R.id.Clue);
    EditText edittext = (EditText)findViewById(R.id.editText);
    String hint;
    String answer;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        Log.d("hi","hello");
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_level_1);
        int level = settings.getInt("level", 1);

            switch (level) {
                case 1:  level1();
                         break;
                default: 
                         break;
            }

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.level_1, menu);
        return true;
    }

    public void level1()    {
        editor.putInt("level", 1); // only needs to be done for level 1
        editor.commit();
        Clue.setText("Bartholdi was my creator, I carry fire and knowledge, what am I?");
        hint = "July IV MDCCLXXVI";
        answer = "statue of liberty";
    }
    public void answer()    {       
        String useranswer = edittext.toString();
        if (useranswer.equalsIgnoreCase(answer))    {// if they get the correct answer
            int leveltest = settings.getInt("level", 1);
            editor.putInt("level", leveltest+1); //adds one level to the current level
            editor.commit();
        }

    }
    public void hint()  { //function that displays the hint

    }

}

level_1 xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".Level_1" >

    <TextView
        android:id="@+id/Clue"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="116dp"
        android:text="Clue" />

    <EditText
        android:id="@+id/editText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/Clue"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="80dp"
        android:ems="10" >

        <requestFocus />
    </EditText>

    <Button
        android:id="@+id/Submit"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignRight="@+id/editText"
        android:layout_marginBottom="50dp"
        android:text="Submit" 
        android:onClick="answer"/>

    <Button
        android:id="@+id/Hint"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/Submit"
        android:layout_alignBottom="@+id/Submit"
        android:layout_alignLeft="@+id/editText"
        android:text="Hint" 
        android:onClick="Hint"/>

</RelativeLayout>

list :

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.treasurehunt"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.treasurehunt.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name="com.example.treasurehunt.Level_1"
            android:label="@string/title_activity_level_1" >
        </activity>
    </application>

</manifest>

Answer 1

您似乎遇到了 NullPointerException。

关于字段声明

TextView Clue = (TextView)findViewById(R.id.Clue);
EditText edittext = (EditText)findViewById(R.id.editText);

将赋值移动到 onCreate()

public class Level_1 extends Activity 
{

       // Other members ....

    TextView Clue = (TextView)findViewById(R.id.Clue);
    EditText edittext = (EditText)findViewById(R.id.editText);

     @Override
     protected void onCreate(Bundle savedInstanceState) {
            Log.d("hi","hello");
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_level_1);

            // Assignemnts should be here
            Clue = (TextView)findViewById(R.id.Clue);
            edittext = (EditText)findViewById(R.id.editText);

            int level = settings.getInt("level", 1);

                switch (level) {
                    case 1:  level1();
                             break;
                    default: 
                             break;
                }
      }

}