如何在Android上调用Clojure? [英] How does one invoke Clojure on Android?
问题描述
TL; DR:我无法在Android中调用Clojure方法.我收到错误消息，我不确定为什么.
TL;DR: I can't invoke Clojure methods in Android; I get an error and I'm not sure why.
我正在为学校项目构建一个Android应用程序.我已经学习了Clojure，并且希望将其用于我的应用程序的某些部分.(我不是的目的是要用Clojure编写整个程序，只是几个库.)
I am building an Android app for a school project. I've learned Clojure, and I would like to use it for parts of my application. (I am not aiming to write the entire thing in Clojure—just a few libraries.)
我已经能够将Clojure程序编译为 .jar 并从笔记本电脑上运行的Java调用它，但我什至无法在Android应用程式！我猜我想念图书馆或其他东西，但是我在这里很漂亮.
I've been able to compile a Clojure program into a .jar and invoke it from Java running on my laptop, but I haven't been able to call even built-in functions in an Android app! I’m guessing I’m missing a library or something, but I’m pretty at sea here.
我进行了以下测试:
MainActivity.java :
package org.wiersdorf.ashton.clojureinterop;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import clojure.java.api.Clojure;
import clojure.lang.IFn;
public class MainActivity extends AppCompatActivity {
private Button BoomButton;
private TextView myText;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
BoomButton = (Button) findViewById(R.id.my_button);
myText = (TextView) findViewById(R.id.my_text);
BoomButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
IFn plus = Clojure.var("clojure.core", "+");
String foo = plus.invoke(1, 2).toString();
myText.setText("Text: " + foo);
}
});
}
}
activity_main.xml :
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:id="@+id/my_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="@+id/my_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:layout_marginBottom="8dp"
android:text="Button"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/my_text" />
</android.support.constraint.ConstraintLayout>
当我单击显示的按钮时，这是我得到的错误:
When I click the button that shows up, this is the error I get:
2018-11-17 23:05:01.313 16202-16202/org.wiersdorf.ashton.clojureinterop E/AndroidRuntime: FATAL EXCEPTION: main
Process: org.wiersdorf.ashton.clojureinterop, PID: 16202
java.lang.ExceptionInInitializerError
at clojure.lang.Reflector.invokeInstanceMethod(Reflector.java:97)
at clojure.core$fn__8373.invokeStatic(core.clj:7032)
at clojure.core$fn__8373.invoke(core.clj:7027)
at clojure.core__init.load(Unknown Source:7027)
at clojure.core__init.<clinit>(Unknown Source:94)
at java.lang.Class.classForName(Native Method)
at java.lang.Class.forName(Class.java:453)
at clojure.lang.RT.classForName(RT.java:2205)
at clojure.lang.RT.classForName(RT.java:2214)
at clojure.lang.RT.loadClassForName(RT.java:2233)
at clojure.lang.RT.load(RT.java:451)
at clojure.lang.RT.load(RT.java:426)
at clojure.lang.RT.doInit(RT.java:469)
at clojure.lang.RT.<clinit>(RT.java:336)
at clojure.lang.Namespace.<init>(Namespace.java:34)
at clojure.lang.Namespace.findOrCreate(Namespace.java:176)
at clojure.lang.Var.intern(Var.java:151)
at clojure.java.api.Clojure.var(Clojure.java:82)
at clojure.java.api.Clojure.<clinit>(Clojure.java:96)
at clojure.java.api.Clojure.var(Clojure.java:82)
at org.wiersdorf.ashton.clojureinterop.MainActivity$1.onClick(MainActivity.java:28)
at android.view.View.performClick(View.java:6294)
at android.view.View$PerformClick.run(View.java:24770)
at android.os.Handler.handleCallback(Handler.java:790)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
Caused by: java.lang.NoSuchMethodException: canAccess [class java.lang.Object]
at java.lang.invoke.MethodHandles$Lookup.findVirtual(MethodHandles.java:906)
at clojure.lang.Reflector.<clinit>(Reflector.java:38)
有什么想法吗?提前致谢.:)
Any ideas? Thanks in advance. :)
推荐答案
The method canAccess was added in Java 9 (see here).
从显示为 canAccess 的NoSuchMethodException的堆栈跟踪来看，您使用的是用Java 9或更高版本编译的Clojure jar，而您的Android系统使用的是较早的JRE.
Judging by that stacktrace, which shows a NoSuchMethodException for canAccess, you're using a Clojure jar that was compiled with Java 9 or above, and your Android system is using an earlier JRE.
如果您可以在Android上升级JRE，或切换到兼容的Clojure版本，则应该对其进行修复.
If you can either upgrade your JRE on Android, or switch to a compatible version of Clojure, that should fix it.
这篇关于如何在Android上调用Clojure?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
