我想感受一下屏幕的压力。当我运行应用程序显示一条消息时,我有另一个问题,当我得到屏幕的压力时,是否可以用一些数学或物理学将重量( Unfortunately, Application has stopped.
)转换为重量?下面是我的代码:
EDIT:我在平板电脑上运行这个应用程序
package com.realscale.stefanrafa;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MotionEvent;
import android.widget.TextView;
public class MainActivity extends Activity {
TextView textinfo;
MotionEvent pressure;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textinfo = (TextView) findViewById(R.id.Information);
float press = pressure.getPressure();
textinfo.setText("Scale: " + (int) press);
}
@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;
}
}
错误日志:
08-30 19:53:40.620: W/ActivityThread(29458): Application com.realscale.stefanrafa can be debugged on port 8100... 08-30 19:53:40.710: D/AndroidRuntime(29458): Shutting down VM 08-30 19:53:40.710: W/dalvikvm(29458): threadid=1: thread exiting with uncaught exception (group=0x41a0c2a0)
08-30 19:53:40.715: E/AndroidRuntime(29458): FATAL EXCEPTION: main 08-30 19:53:40.715: E/AndroidRuntime(29458): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.realscale.stefanrafa/com.realscale.stefanrafa.MainActivity}: java.lang.NullPointerException
08-30 19:53:40.715: E/AndroidRuntime(29458): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2110)
08-30 19:53:40.715: E/AndroidRuntime(29458): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2135)
08-30 19:53:40.715: E/AndroidRuntime(29458): at android.app.ActivityThread.access$700(ActivityThread.java:140)
08-30 19:53:40.715: E/AndroidRuntime(29458): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1237)
08-30 19:53:40.715: E/AndroidRuntime(29458): at android.os.Handler.dispatchMessage(Handler.java:99)
08-30 19:53:40.715: E/AndroidRuntime(29458): at android.os.Looper.loop(Looper.java:137)
08-30 19:53:40.715: E/AndroidRuntime(29458): at android.app.ActivityThread.main(ActivityThread.java:4921)
08-30 19:53:40.715: E/AndroidRuntime(29458): at java.lang.reflect.Method.invokeNative(Native Method)
08-30 19:53:40.715: E/AndroidRuntime(29458): at java.lang.reflect.Method.invoke(Method.java:511)
08-30 19:53:40.715: E/AndroidRuntime(29458): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038) 08-30 19:53:40.715: E/AndroidRuntime(29458): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805)
08-30 19:53:40.715: E/AndroidRuntime(29458): at dalvik.system.NativeStart.main(Native Method)
08-30 19:53:40.715: E/AndroidRuntime(29458): Caused by: java.lang.NullPointerException
08-30 19:53:40.715: E/AndroidRuntime(29458): at com.realscale.stefanrafa.MainActivity.onCreate(MainActivity.java:19)
08-30 19:53:40.715: E/AndroidRuntime(29458): at android.app.Activity.performCreate(Activity.java:5188)
08-30 19:53:40.715: E/AndroidRuntime(29458): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094)
08-30 19:53:40.715: E/AndroidRuntime(29458): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2074)
08-30 19:53:40.715: E/AndroidRuntime(29458): ... 11 more
发布于 2013-08-31 01:54:05
压力是一个从0到1的浮点数。它的意思是硬件相关的。即使有硬件压力传感器,实际力和getPressure()
返回值之间的映射仍然取决于设备。其他设备只返回一个常量值。
另外,力或重量(以牛顿为单位)与质量(以克为单位)是不同的。参见http://en.wikipedia.org/wiki/Mass_versus_weight。
如果您需要有关异常的帮助,那么您应该发布抛出异常的源代码和代码行。adb log
是你的朋友。
编辑:
使用未初始化的压力。它只是声明了,但没有设置任何值,所以它是null
。调用它的一个方法是一个NullPointerException。只有View
%s(小工具)才能接收MotionEvent
%s。您需要对您的活动执行一些操作(例如,膨胀布局),然后将触摸侦听器设置为布局的视图之一:
someView.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
float pressure = event.getPressure();
}
});
https://stackoverflow.com/questions/18538513
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