android - 字符串数组上的 NullpointerException

Question

我的 android 应用程序有问题..
我使用字符串数组在 TextView 中显示那里的项目，但每次我得到 NullpointerException，你能帮我看看我哪里错了吗？
代码如下:

public class test extends Activity {

        String [] myString ;

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


        myString = getResources().getStringArray(R.array.myArray);


        String q = myString[1];

        TextView tv = (TextView) findViewById(R.id.text2);
        tv.setText(q);
    }
}

和我的 xml 代码:

 <string-array name="myArray">
    <item > string 1</item>

    <item > string 2</item>

    <item> string 3</item>

    <item > string 4</item>
 </string-array>

日志:

04-15 11:38:27.647: E/AndroidRuntime(285): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.app/com.example.app.test}: java.lang.NullPointerException
04-15 11:38:27.647: E/AndroidRuntime(285):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
04-15 11:38:27.647: E/AndroidRuntime(285):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
04-15 11:38:27.647: E/AndroidRuntime(285):  at android.app.ActivityThread.access$2300(ActivityThread.java:125)
04-15 11:38:27.647: E/AndroidRuntime(285):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
04-15 11:38:27.647: E/AndroidRuntime(285):  at android.os.Handler.dispatchMessage(Handler.java:99)
04-15 11:38:27.647: E/AndroidRuntime(285):  at android.os.Looper.loop(Looper.java:123)
04-15 11:38:27.647: E/AndroidRuntime(285):  at android.app.ActivityThread.main(ActivityThread.java:4627)
04-15 11:38:27.647: E/AndroidRuntime(285):  at java.lang.reflect.Method.invokeNative(Native Method)
04-15 11:38:27.647: E/AndroidRuntime(285):  at java.lang.reflect.Method.invoke(Method.java:521)
04-15 11:38:27.647: E/AndroidRuntime(285):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
04-15 11:38:27.647: E/AndroidRuntime(285):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
04-15 11:38:27.647: E/AndroidRuntime(285):  at dalvik.system.NativeStart.main(Native Method)
04-15 11:38:27.647: E/AndroidRuntime(285): Caused by: java.lang.NullPointerException
04-15 11:38:27.647: E/AndroidRuntime(285):  at com.example.app.test.onCreate(vovochka.java:29)
04-15 11:38:27.647: E/AndroidRuntime(285):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
04-15 11:38:27.647: E/AndroidRuntime(285):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)

Answer 1

在按钮单击时设置 TextView 中的文本。

在 arrays.xml 中

<?xml version="1.0" encoding="utf-8"?>
<resources>
<string-array name="myArray">
<item > string 1</item>
<item > string 2</item>
<item> string 3</item>
<item > string 4</item>
</string-array>
</resources>

在你的 Activity 中

String[] myString;
TextView _tv;
Button b;
String q;

在 onCreate() 中

setContentView(R.layout.activity_main);
myString = getResources().getStringArray(R.array.myArray);
q = myString[1];
_tv = (TextView) findViewById( R.id.tv ); 
b= (Button) findViewById(R.id.button1);
b.setOnClickListener(new OnClickListener()
{

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        _tv.setText(q);

    }

});