Android 安卓应用程序崩溃，出现“故障”；不幸的是，<；appname>；“已经停止”；一旦我尝试启动一项活动

以下是主要活动代码：

package com.vanitfyf.karko;

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

public class MainActivity extends Activity {



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


        TextView textView1 = (TextView) findViewById(R.id.textView1);
        textView1.setTextColor(Color.BLUE);
        Button button1 = (Button) findViewById(R.id.button1);


        button1.setOnClickListener(new OnClickListener()
            {
                public void onClick(View v)
            {
                Toast.makeText(MainActivity.this, "entering debug mode", Toast.LENGTH_LONG).show();
                startActivity(new Intent(MainActivity.this, SecondActivity.class ));
            }

        });

    Button button2 = (Button)findViewById(R.id.button2);
    button2.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                Toast.makeText(MainActivity.this, "entering normal mode", Toast.LENGTH_LONG).show();
                startActivity(new Intent(MainActivity.this, ThirdActivity.class));

            }
        });
    }





   /* @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;
    }*/

}

package com.vanitfyf.karko;

import android.app.*;
import android.content.*;
import android.os.*;
import android.widget.*;

public class SecondActivity extends Activity
{

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




protected void show(Context context) {
    Toast.makeText(context, "welcome", Toast.LENGTH_LONG).show();

    }


}

package com.vanitfyf.karko;

import android.app.*;
import android.os.*;
import android.widget.*;

public class ThirdActivity extends Activity { 

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

    TextView textview2 = (TextView) findViewById(R.id.textview2);
    textview2.setText("Welcome to normal mode");

    }
  }

以下是第二个活动代码：

package com.vanitfyf.karko;

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

public class MainActivity extends Activity {



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


        TextView textView1 = (TextView) findViewById(R.id.textView1);
        textView1.setTextColor(Color.BLUE);
        Button button1 = (Button) findViewById(R.id.button1);


        button1.setOnClickListener(new OnClickListener()
            {
                public void onClick(View v)
            {
                Toast.makeText(MainActivity.this, "entering debug mode", Toast.LENGTH_LONG).show();
                startActivity(new Intent(MainActivity.this, SecondActivity.class ));
            }

        });

    Button button2 = (Button)findViewById(R.id.button2);
    button2.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                Toast.makeText(MainActivity.this, "entering normal mode", Toast.LENGTH_LONG).show();
                startActivity(new Intent(MainActivity.this, ThirdActivity.class));

            }
        });
    }





   /* @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;
    }*/

}

package com.vanitfyf.karko;

import android.app.*;
import android.content.*;
import android.os.*;
import android.widget.*;

public class SecondActivity extends Activity
{

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




protected void show(Context context) {
    Toast.makeText(context, "welcome", Toast.LENGTH_LONG).show();

    }


}

package com.vanitfyf.karko;

import android.app.*;
import android.os.*;
import android.widget.*;

public class ThirdActivity extends Activity { 

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

    TextView textview2 = (TextView) findViewById(R.id.textview2);
    textview2.setText("Welcome to normal mode");

    }
  }

这是第三个活动代码：

package com.vanitfyf.karko;

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

public class MainActivity extends Activity {



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


        TextView textView1 = (TextView) findViewById(R.id.textView1);
        textView1.setTextColor(Color.BLUE);
        Button button1 = (Button) findViewById(R.id.button1);


        button1.setOnClickListener(new OnClickListener()
            {
                public void onClick(View v)
            {
                Toast.makeText(MainActivity.this, "entering debug mode", Toast.LENGTH_LONG).show();
                startActivity(new Intent(MainActivity.this, SecondActivity.class ));
            }

        });

    Button button2 = (Button)findViewById(R.id.button2);
    button2.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                Toast.makeText(MainActivity.this, "entering normal mode", Toast.LENGTH_LONG).show();
                startActivity(new Intent(MainActivity.this, ThirdActivity.class));

            }
        });
    }





   /* @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;
    }*/

}

package com.vanitfyf.karko;

import android.app.*;
import android.content.*;
import android.os.*;
import android.widget.*;

public class SecondActivity extends Activity
{

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




protected void show(Context context) {
    Toast.makeText(context, "welcome", Toast.LENGTH_LONG).show();

    }


}

package com.vanitfyf.karko;

import android.app.*;
import android.os.*;
import android.widget.*;

public class ThirdActivity extends Activity { 

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

    TextView textview2 = (TextView) findViewById(R.id.textview2);
    textview2.setText("Welcome to normal mode");

    }
  }

当我试图按下打开第三个活动的按钮时，应用程序就会崩溃。第三个活动不显示。在一次飞机旅行中，我一直在沮丧地揪头发，试图找出哪里出了问题，但我仍然没有弄明白。顺便说一下，所有活动都引用了正确的layout.xmls

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有什么建议吗？我在这方面是新手（显然），所以我非常感谢任何帮助

根据您提供的代码，您的应用程序在您描述的情况下会崩溃有几个直观的原因

确保在清单中声明第三个活动，否则在启动活动时将收到空指针异常（这可能导致应用程序崩溃）。这是应用程序中所有活动的要求。请参阅此处的更多信息：

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此外，请验证第三个活动“activitythird”的布局是否为有效的资源名称，并包含您在第三个活动“textview2”中引用的TextView。如果使用Eclipse ADT或Android Studio等IDE，则应收到未找到资源的指示；如果不是自动的，至少在编译时。这同样适用于启动第三个活动“button2”的按钮。

如果它没有在清单中声明，它也会显示在LogCat中，stacktrace在哪里？ThirdActivity布局是否有id为TextView 2的TextView？你在舱单上申报了第三十名吗？@2dee:天哪，就是这样。我没有在清单中声明该活动！谢谢，谢谢。我忘了在清单中声明正在崩溃的活动！