1

我有下一个问题：

无法启动活动组件信息 java.lang.nullpointerexception

我做一个带有偏好的程序，这是代码：

package com.toogle.button;

import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.graphics.Color;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.CompoundButton;
import android.widget.CompoundButton.OnCheckedChangeListener;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.ToggleButton;

public class MainActivity extends Activity implements OnCheckedChangeListener {

EditText editable;
TextView texto;
ToggleButton toggle;


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

    LinearLayout ll = (LinearLayout) findViewById(R.id.ll);

    SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(getBaseContext());
    boolean fondo = sp.getBoolean("checkbox", true);
    if (fondo == true){
        ll.setBackgroundColor(Color.BLUE);

    }   

    String plist = sp.getString("lista", null); **//HERE IS THE PROBLEM**
    if (plist.equals("1")){
            ll.setBackgroundColor(Color.GREEN);
    }   



    String toast = sp.getString("nombre", null);
    if(toast.equals("emi")){
        Toast t = Toast.makeText(this, "bien", Toast.LENGTH_SHORT);
        t.show();
    }



    editable = (EditText) findViewById(R.id.etEditable);
    texto = (TextView) findViewById(R.id.tvTexto);
    toggle = (ToggleButton) findViewById(R.id.tgToggle);
    toggle.setOnCheckedChangeListener(this);

}



@Override





public void onCheckedChanged(CompoundButton arg0, boolean arg1) {
    // TODO Auto-generated method stub
    if (toggle.isChecked()){
        editable.setTextColor(Color.RED);
        editable.setTextSize(30);
        texto.setText("Activado");

    }else{
        editable.setTextColor(Color.BLACK);
        editable.setTextSize(20);
        texto.setText("Desactivado");
    }
}



@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    super.onCreateOptionsMenu(menu);
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.main, menu);


    return true;
}



@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // TODO Auto-generated method stub
    switch(item.getItemId()){
    case R.id.iConoce:
    Intent c = new Intent("com.toogle.button.CONOCE");
    startActivity (c);

        break;

    case R.id.iPrefs:
    Intent p = new Intent("com.toogle.button.PREFS");
    startActivity (p);

        break;

    case R.id.iSalir:
        finish();
        break;

    }

    return false;

}




}

数组 XML 文件： 

<?xml version="1.0" encoding="utf-8"?>


<string-array name="lista">
<item>Uno</item>
<item>Dos</item>
<item>Tres</item>
<item>Cuatro</item>



</string-array>
<!-- Values -->
<string-array name="lValores">
<item>1</item>
<item>2</item>
<item>3</item>
<item>4</item>



</string-array>

这是logcat：

    08-24 20:28:49.689: E/AndroidRuntime(31419): FATAL EXCEPTION: main
08-24 20:28:49.689: E/AndroidRuntime(31419): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.toogle.button/com.toogle.button.MainActivity}: java.lang.NullPointerException
08-24 20:28:49.689: E/AndroidRuntime(31419):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
08-24 20:28:49.689: E/AndroidRuntime(31419):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
08-24 20:28:49.689: E/AndroidRuntime(31419):    at android.app.ActivityThread.access$2300(ActivityThread.java:125)
08-24 20:28:49.689: E/AndroidRuntime(31419):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
08-24 20:28:49.689: E/AndroidRuntime(31419):    at android.os.Handler.dispatchMessage(Handler.java:99)
08-24 20:28:49.689: E/AndroidRuntime(31419):    at android.os.Looper.loop(Looper.java:123)
08-24 20:28:49.689: E/AndroidRuntime(31419):    at android.app.ActivityThread.main(ActivityThread.java:4627)
08-24 20:28:49.689: E/AndroidRuntime(31419):    at java.lang.reflect.Method.invokeNative(Native Method)
08-24 20:28:49.689: E/AndroidRuntime(31419):    at java.lang.reflect.Method.invoke(Method.java:521)
08-24 20:28:49.689: E/AndroidRuntime(31419):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:876)
08-24 20:28:49.689: E/AndroidRuntime(31419):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:634)
08-24 20:28:49.689: E/AndroidRuntime(31419):    at dalvik.system.NativeStart.main(Native Method)
08-24 20:28:49.689: E/AndroidRuntime(31419): Caused by: java.lang.NullPointerException
08-24 20:28:49.689: E/AndroidRuntime(31419):    at com.toogle.button.MainActivity.onCreate(MainActivity.java:43)
08-24 20:28:49.689: E/AndroidRuntime(31419):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
08-24 20:28:49.689: E/AndroidRuntime(31419):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
08-24 20:28:49.689: E/AndroidRuntime(31419):    ... 11 more

谢谢。

4

1 回答 1

0

由于您将 String 的默认值设置为nullin

String plist = sp.getString("lista", null);

NullPointerException当您尝试对其调用方法时，可能会导致以下情况。

if (plist.equals("1")){

尝试使用：

String plist = sp.getString("lista", "");

反而。

于 2013-08-25T02:27:11.587 回答