Question

使用getRessources（）从string.xml获取值时出错。

这是我的档案：

import android.app.Activity;
import android.util.Log;
import android.content.Context;


public class mailing extends Activity {
    int[] mail_images= new int[]{0, R.drawable.simple, R.drawable.p};
    String[] mail_array_spinner = new String[]{getResources().getString(R.string.type_select),getResources().getString(R.string.maillist)};

    public int get_image_id(String check){
        int got=-1;

        for(int i=0;i<mail_images.length;i++){
            if(mail_array_spinner[i].equals(check)){
                got=i;
            }
        }
        return mail_images[got];
    }
}

我的应用程序在读取代码时停止，错误来自：

String[] mail_array_spinner = new String[]{getResources().getString(R.string.type_select),getResources().getString(R.string.maillist)};

这里是日志：

01-02 16:59:39.255 6087-6087/com.example.xx.cxeapp D/typei: mail
01-02 16:59:39.257 6087-6087/com.example.xx.cxeapp D/AndroidRuntime: Shutting down VM
01-02 16:59:39.258 6087-6087/com.example.xx.cxeapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.xx.cxeapp, PID: 6087
java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference
        at android.content.ContextWrapper.getResources(ContextWrapper.java:87)
        at android.view.ContextThemeWrapper.getResources(ContextThemeWrapper.java:81)
        at com.example.mouh.myapplication.mail.<init>(mail.java:11)
        at Adapters.InProgressListAdapter.getView(InProgressListAdapter.java:62)
        at android.widget.AbsListView.obtainView(AbsListView.java:2346)
        at android.widget.ListView.measureHeightOfChildren(ListView.java:1280)
        at android.widget.ListView.onMeasure(ListView.java:1188)
        at android.view.View.measure(View.java:18788)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
        at android.support.design.widget.CoordinatorLayout.onMeasureChild(CoordinatorLayout.java:610)
        at android.support.design.widget.CoordinatorLayout.onMeasure(CoordinatorLayout.java:677)
        at android.view.View.measure(View.java:18788)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1465)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:748)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:630)
        at android.view.View.measure(View.java:18788)
        at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1489)
        at android.view.View.measure(View.java:18788)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:901)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:630)
        at android.view.View.measure(View.java:18788)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1465)
        at android.widget.LinearLayout.measureHorizontal(LinearLayout.java:1112)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:632)
        at android.view.View.measure(View.java:18788)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1465)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:748)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:630)
        at android.view.View.measure(View.java:18788)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
        at android.support.v7.internal.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135)
        at android.view.View.measure(View.java:18788)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1465)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:748)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:630)
        at android.view.View.measure(View.java:18788)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
        at android.view.View.measure(View.java:18788)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1465)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:748)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:630)
        at android.view.View.measure(View.java:18788)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
        at com.android.internal.policy.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2643)
        at android.view.View.measure(View.java:18788)
        at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2100)
        at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1216)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1452)

有任何帮助来解决这个问题吗？感谢。

Answer 1

您尚未在onCreate()内编写代码，请执行以下操作

    public class mailing extends Activity {
        int[] mail_images; 
        String[] mail_array_spinner;
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            mail_images= new int[]{0, R.drawable.simple, R.drawable.p};
            mail_array_spinner = new String[]{getResources().getString(R.string.type_select),getResources().getString(R.string.maillist)};


    }

      public int get_image_id(String check){
            int got=-1;
            mail_images= new int[]{0, R.drawable.simple, R.drawable.p};
            mail_array_spinner = new String[]{getResources().getString(R.string.type_select),getResources().getString(R.string.maillist)};
            for(int i=0;i<mail_images.length;i++){
                if(mail_array_spinner[i].equals(check)){
                    got=i;
                }
            }
            return mail_images[got];
        }

}

Answer 2

您正在尝试在创建活动之前调用getResources（），这会导致空指针异常。在onCreate（）方法中调用getResources。

fh.seek(0,2)

getResources（）返回错误

2 个答案: