当我在Android应用程序中单击“ Notes”按钮时，如何调用NoteMain类

Question

如上。 我确定自己在做什么错。 这是MainActivity.java的代码和NoteMain.java的代码，当我在应用程序加载时单击主屏幕上的Notes按钮时，它说“ Unfortunately,(app name) has stopped 。

不知道为什么 任何帮助表示赞赏。

提前致谢

主要活动：

package com.qub.buildersbuddy;

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends Activity {

    Button buttonConverter; 
    Button buttonCalculator;
    Button buttonNotePad;



    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);



        Button ConvertBtn = (Button) findViewById(R.id.butonConverter);
        ConvertBtn.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MainActivity.this,CentInch.class);
                startActivity(intent);

            }
        });


        Button CalcBtn = (Button) findViewById(R.id.buttonCalc);
        CalcBtn.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MainActivity.this,Calculator.class);
                startActivity(intent);

            }
        });

        Button NoteBtn = (Button) findViewById(R.id.buttonNotes);
        NoteBtn.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MainActivity.this,NoteMain.class);
                startActivity(intent);

            }
        });
    }

    public void setupConverterButton(){
        buttonConverter = (Button) findViewById(R.id.butonConverter);
        // Button messageButton = (Button) findViewById(R.id.butonConverter);

}

    public void CentToInch(){
        buttonConverter.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                //opening the
                try{
                    Class centClass = Class
                            .forName("com.qub.buildersbuddy.CentInch");
                    Intent myintent = new Intent(MainActivity.this,centClass);
            startActivity(myintent);
                }catch (ClassNotFoundException e){
                    e.printStackTrace();

                }

            }
    });

}


public void setupCalculatorButton(){
    buttonCalculator = (Button) findViewById(R.id.buttonCalc);
    // Button messageButton = (Button) findViewById(R.id.butonConverter);

}

public void Calculator(){
    buttonCalculator.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            //opening the
            try{
                Class calcClass = Class
                        .forName("com.qub.buildersbuddy.Calculator");
                Intent myintent = new Intent(MainActivity.this,calcClass);
        startActivity(myintent);
            }catch (ClassNotFoundException e){
                e.printStackTrace();

            }

        }
});

}

public void setupNotesButton(){
    buttonNotePad = (Button) findViewById(R.id.buttonNotes);
    // Button messageButton = (Button) findViewById(R.id.butonConverter);

}

public void Notes(){
    buttonNotePad.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            //opening the
            try{
                Class NoteMain = Class
                        .forName("com.qub.buildersbuddy.NoteMain");
                Intent myintent = new Intent(MainActivity.this,NoteMain);
        startActivity(myintent);
            }catch (ClassNotFoundException e){
                e.printStackTrace();

            }

        }
});

}

}

NoteMain

package com.qub.buildersbuddy;


import java.util.ArrayList;
import java.util.Map;
import java.util.Map.Entry;

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.Button;
import android.widget.ListView;

public class NoteMain extends Activity implements OnItemClickListener, OnClickListener {

    private SharedPreferences spNotes;
    private ArrayList<Note> notes;
    private Button addNote;

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

        this.addNote = (Button) findViewById(R.id.addNoteButton);
        this.addNote.setOnClickListener(this);
        spNotes = getSharedPreferences("notes", Context.MODE_PRIVATE);

    }

  @Override
    protected void onResume() {
        super.onResume();
        showNotes();
        ListView list = (ListView) findViewById(R.id.listNotes);
        CustomAdapter aa = new CustomAdapter(this, getLayoutInflater(), this.notes, spNotes);
        list.setAdapter(aa);
        list.setOnItemClickListener(this);
    }

    private void showNotes() {
        this.notes = new ArrayList<Note>();
        Map map = spNotes.getAll();
        for (Object o : map.entrySet()) {
            Entry e = (Entry<String, String>) o;
            this.notes.add(new Note((String)e.getKey(), (String)e.getValue()));
        }
    }

    @Override
    public void onItemClick(AdapterView<?> arg0, View arg1, int position, long id) {
        Intent intent = new Intent(this, NoteActivity.class);
        intent.putExtra("title", this.notes.get(position).getTitle());
        intent.putExtra("text", this.notes.get(position).getText());
        startActivity(intent);
    }


    @Override
    public void onClick(View arg0) {
        Intent intent = new Intent(this, NoteActivity.class);
        startActivity(intent);
    }

}

AndroidManifest

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

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="18" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.qub.buildersbuddy.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.qub.buildersbuddy.CentInch"
            android:label="@string/title_activity_cent_inch" >
        </activity>
        <activity
            android:name="com.qub.buildersbuddy.Calculator"
            android:label="@string/title_activity_calculator" >
        </activity>
         <activity
            android:name="com.qub.buildersbuddy.NotePad"
            android:label="@string/title_activity_note" >
        </activity>



    </application>

</manifest>

Answer 1

可能是因为您没有在清单中定义NoteMain活动。

<activity
    android:name="com.qub.buildersbuddy.NoteMain"
    android:label="@string/title_activity_note" >
</activity>