如何在TextView上显示bmp颜色值

Question

我想得到一个颜色值bmp图像在Textview上显示

这是我的 bmp 图片，大小为 16X24

我尝试做一个按钮，当按钮被按下时bmp图片颜色值会显示在TextView中

但是按下按钮后程序崩溃了

public class MainActivity extends Activity 
{
    int mArrayColor[];
    int count = 0;
    int color;

    protected void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final TextView show = (TextView)findViewById(R.id.show);
        Button btn = (Button)findViewById(R.id.bitbtn);

        btn.setOnClickListener(new Button.OnClickListener() 
        {
            public void onClick(View v) 
            {
                Bitmap bitmap = BitmapFactory.decodeResource(getResources(),R.drawable.two);
                int wid = bitmap.getWidth();
                int hei = bitmap.getHeight();


                for(int i=0;i<wid;i++)
                {
                    for(int j=0;j<hei;j++)
                    {
                        color=bitmap.getPixel(i, j); 
                        mArrayColor[count] = color;
                        count++;
                    }
                }
                show.setText(Arrays.toString(mArrayColor));
            }
        });
    }
}

这是为什么？

这是我的日志

11-13 15:54:56.081: D/AndroidRuntime(11262): Shutting down VM
11-13 15:54:56.081: W/dalvikvm(11262): threadid=1: thread exiting with uncaught exception (group=0x41c8bda0)
11-13 15:54:56.081: E/AndroidRuntime(11262): FATAL EXCEPTION: main
11-13 15:54:56.081: E/AndroidRuntime(11262): Process: com.example.bitmapfactory, PID: 11262
11-13 15:54:56.081: E/AndroidRuntime(11262): java.lang.NullPointerException
11-13 15:54:56.081: E/AndroidRuntime(11262):    at com.example.bitmapfactory.MainActivity.onClick(MainActivity.java:41)
11-13 15:54:56.081: E/AndroidRuntime(11262):    at android.view.View.performClick(View.java:4623)
11-13 15:54:56.081: E/AndroidRuntime(11262):    at android.view.View$PerformClick.run(View.java:19230)
11-13 15:54:56.081: E/AndroidRuntime(11262):    at android.os.Handler.handleCallback(Handler.java:733)
11-13 15:54:56.081: E/AndroidRuntime(11262):    at android.os.Handler.dispatchMessage(Handler.java:95)
11-13 15:54:56.081: E/AndroidRuntime(11262):    at android.os.Looper.loop(Looper.java:157)
11-13 15:54:56.081: E/AndroidRuntime(11262):    at android.app.ActivityThread.main(ActivityThread.java:5335)
11-13 15:54:56.081: E/AndroidRuntime(11262):    at java.lang.reflect.Method.invokeNative(Native Method)
11-13 15:54:56.081: E/AndroidRuntime(11262):    at java.lang.reflect.Method.invoke(Method.java:515)
11-13 15:54:56.081: E/AndroidRuntime(11262):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
11-13 15:54:56.081: E/AndroidRuntime(11262):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
11-13 15:54:56.081: E/AndroidRuntime(11262):    at dalvik.system.NativeStart.main(Native Method)

Answer 1

NullPointerException 11-13 15:54:56.081: E/AndroidRuntime(11262):
at com.example.bitmapfactory.MainActivity.onClick

因为mArrayColor是null。

在 mArrayColor 数组中添加项目之前需要使用大小进行初始化。

如果项目大小未知，则使用 ArrayList 而不是 Array。

如何在TextView上显示bmp颜色值

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