请检查给定的代码，我在C ++中使用了相同的代码并进行了少量更改，并且运行良好。我也期待着为Android做这件事。但是我按下“计算”按钮就会崩溃。请告诉我这里的问题是什么。 附：我是初学者。
我的主要文件：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/main"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="Optimum Tilt Angle Calculator"
android:textAppearance="?android:attr/textAppearanceLarge" />
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="Calculate" />
<TextView
android:id="@+id/beta"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="Beta = "
android:textAppearance="?android:attr/textAppearanceLarge" />
<TextView
android:id="@+id/rad"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="H = "
android:textAppearance="?android:attr/textAppearanceLarge" />
我的Tilt.java：
package com.ned.tilt;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class Tilt extends Activity implements android.view.View.OnClickListener {
private static final double PI = 3.142;
private static final double PHI = 24.8508 * (PI / 180);
private static final double Gsc = 1367;
private static final double RO = 0.2;
int i, beta, ang;
double delta, ws, wss, Hom[], Gon[], Kt[], Hd[], Rb, Rb_num, Rb_den, Ra,
Htm, Ht;
int nbar[] = { 17, 47, 75, 105, 135, 162, 198, 228, 258, 288, 318, 344 };
int N[] = { 31, 28, 31, 30, 31, 30, 31, 30, 31, 30, 31, 30 };
double Hm[] = { 4.38, 5.18, 5.93, 6.65, 6.67, 6.40, 5.44, 5.27, 5.62, 5.24,
4.5, 4.11 };
Button cal;
TextView radiation, angle;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
initialize();
cal.setOnClickListener(this);
}
private void initialize() {
// TODO Auto-generated method stub
cal = (Button) findViewById(R.id.button1);
radiation = (TextView) findViewById(R.id.rad);
angle = (TextView) findViewById(R.id.beta);
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
for (i = 0; i <= 11; i++) {
Htm = 0;
delta = 23.45 * (Math.sin((0.986301369) * (PI / 180)
* (284 + (nbar[i]))));
ws = Math.acos(-(Math.tan(PHI)) * (Math.tan(delta * (PI / 180))));
ws = ws * (180 / PI);
Gon[i] = Gsc
* (1 + (0.033 * Math.cos(0.986301369 * (nbar[i])
* (PI / 180))));
Hom[i] = (86400 / PI)
* Gon[i]
* (((Math.cos(PHI)) * (Math.cos(delta * (PI / 180))) * (Math
.sin(ws * (PI / 180)))) + ((ws * (PI / 180)) * (Math
.sin(PHI) * (Math.sin(delta * (PI / 180))))));
Hom[i] = Hom[i] / 3600000;
Kt[i] = Hm[i] / Hom[i];
Hd[i] = (0.96268) - ((1.45200) * (Kt[i]))
+ ((0.27365) * (Kt[i]) * (Kt[i]))
+ ((0.04279) * (Kt[i]) * (Kt[i]) * (Kt[i]))
+ ((0.000246) * (ws))
+ ((0.001189) * (90 - (PHI * (180 / PI)) + delta));
Hd[i] = Hd[i] * Hm[i];
for (beta = 0; beta <= 90; beta++) {
wss = Math.acos(-(Math.tan((PHI) - (beta * (PI / 180))) * (Math
.tan(delta * (PI / 180)))));
wss = wss * (180 / PI);
if (wss > ws) {
wss = ws;
}
Rb_num = ((Math.cos((PHI) - (beta * (PI / 180))))
* (Math.cos(delta * (PI / 180))) * (Math.sin(wss
* (PI / 180))))
+ (((PI / 180) * wss)
* ((Math.sin((PHI) - (beta * (PI / 180))))) * ((Math
.sin(delta * (PI / 180)))));
Rb_den = ((Math.cos(PHI)) * (Math.cos(delta * (PI / 180))) * (Math
.sin(ws * (PI / 180))))
+ (((PI / 180) * (ws) * (Math.sin(PHI)) * (Math
.sin(delta * (PI / 180)))));
Rb = Rb_num / Rb_den;
Ra = ((1 - (Hd[i] / Hm[i])) * (Rb))
+ ((Hd[i] / (2 * Hm[i])) * (1 + (Math.cos(beta
* (PI / 180)))))
+ ((RO / 2) * (1 - (Math.cos(beta * (PI / 180)))));
Ht = Ra * Hm[i];
if (Ht > Htm) {
Htm = Ht;
ang = beta;
}
}
break;
}
radiation.setText("H = " + Htm);
angle.setText("Beta =" + ang);
}
}
logcat的：
02-28 17:25:10.344: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:10.344: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:10.344: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:10.434: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:10.434: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:10.894: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:10.894: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:10.924: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:10.944: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:11.144: D/libEGL(773): loaded /system/lib/egl/libEGL_emulation.so
02-28 17:25:11.154: D/(773): HostConnection::get() New Host Connection established 0x2a186bf0, tid 773
02-28 17:25:11.184: D/libEGL(773): loaded /system/lib/egl/libGLESv1_CM_emulation.so
02-28 17:25:11.193: D/libEGL(773): loaded /system/lib/egl/libGLESv2_emulation.so
02-28 17:25:11.335: W/EGL_emulation(773): eglSurfaceAttrib not implemented
02-28 17:25:11.383: D/OpenGLRenderer(773): Enabling debug mode 0
02-28 17:25:11.394: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:11.403: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:11.415: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:11.444: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:11.444: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:11.464: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:11.464: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:11.464: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:11.464: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:11.474: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:11.514: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:11.524: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:11.524: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:11.524: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:11.724: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:11.774: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:25:11.864: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:49.747: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:49.747: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:49.747: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:49.767: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:49.767: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:49.767: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:49.777: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:49.777: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:49.910: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:49.910: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:51.397: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:51.397: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:51.473: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:51.473: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:51.473: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:51.477: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:51.477: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:51.477: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:51.477: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:51.477: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:51.497: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:51.497: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:51.497: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:51.497: W/Trace(773): Unexpected value from nativeGetEnabledTags: 0
02-28 17:26:51.527: D/AndroidRuntime(773): Shutting down VM
02-28 17:26:51.527: W/dalvikvm(773): threadid=1: thread exiting with uncaught exception (group=0x40a70930)
02-28 17:26:51.537: E/AndroidRuntime(773): FATAL EXCEPTION: main
02-28 17:26:51.537: E/AndroidRuntime(773): java.lang.NullPointerException
02-28 17:26:51.537: E/AndroidRuntime(773): at com.ned.tilt.Tilt.onClick(Tilt.java:53)
02-28 17:26:51.537: E/AndroidRuntime(773): at android.view.View.performClick(View.java:4202)
02-28 17:26:51.537: E/AndroidRuntime(773): at android.view.View$PerformClick.run(View.java:17340)
02-28 17:26:51.537: E/AndroidRuntime(773): at android.os.Handler.handleCallback(Handler.java:725)
02-28 17:26:51.537: E/AndroidRuntime(773): at android.os.Handler.dispatchMessage(Handler.java:92)
02-28 17:26:51.537: E/AndroidRuntime(773): at android.os.Looper.loop(Looper.java:137)
02-28 17:26:51.537: E/AndroidRuntime(773): at android.app.ActivityThread.main(ActivityThread.java:5039)
02-28 17:26:51.537: E/AndroidRuntime(773): at java.lang.reflect.Method.invokeNative(Native Method)
02-28 17:26:51.537: E/AndroidRuntime(773): at java.lang.reflect.Method.invoke(Method.java:511)
02-28 17:26:51.537: E/AndroidRuntime(773): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
02-28 17:26:51.537: E/AndroidRuntime(773): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
02-28 17:26:51.537: E/AndroidRuntime(773): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：1)
你没有初始化你的Hom []，Gon []，Kt []，Hd []数组，但是你试图在你的循环中访问并设置它。一个例子是：
Hd[i] = Hd[i] * Hm[i];
由于您正在处理长度为12的循环，因此可以为它们初始化空数组。