android 得到另一个Activity的返回值时报错
activity1.kt
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
button.setOnClickListener() {
val username: String = editText.text.toString()
val intent = Intent("WZC.activity1")
startActivity(intent)
intent.putExtra("username", username)
//startActivity(intent)
startActivityForResult(intent, 0)
}
}
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
super.onActivityResult(requestCode, resultCode, data)
val result = data!!.extras.get("result").toString()
textView2.text = result
}
activity2.kt
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main2)
val username = intent.extras.get("username") as String
textView.text = "Welcome," + username
button5.setOnClickListener(){
val intent = Intent("MainActivity")
intent.putExtra("result","Result from Main2Activity.")
setResult(0,intent)
finish()
}
}
}
## 错误日志
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.ruaaaaaaaa.myapplication/com.example.ruaaaaaaaa.myapplication.Main2Activity}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object android.os.Bundle.get(java.lang.String)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object android.os.Bundle.get(java.lang.String)' on a null object reference
at com.example.ruaaaaaaaa.myapplication.Main2Activity.onCreate(Main2Activity.kt:14)
at android.app.Activity.performCreate(Activity.java:5937)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Application terminated.
