当在模拟器中测试我的应用程序时(我正在使用Eclipse),它显示“应用程序Counter(com.ian.counter)意外停止。请重试。”运行时。我已经搜索了答案,但是没有找到答案。有人知道这个问题吗?
码:
package com.ian.counter;
import android.app.Activity;
import android.widget.TextView;
import android.os.Bundle;
import android.widget.Toast;
public class CounterActivity extends Activity {
/** Called when the activity is first created. */
TextView textView1 = (TextView) this.findViewById(R.id.textView1);
int count = 0;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
public void Count(){
count ++;
textView1.setText(Integer.toString(count));
}
}
Logcat:
12-28 16:59:20.615: D/AndroidRuntime(353): Shutting down VM
12-28 16:59:20.686: W/dalvikvm(353): threadid=1: thread exiting with uncaught exception (group=0x40015560)
12-28 16:59:20.756: E/AndroidRuntime(353): FATAL EXCEPTION: main
12-28 16:59:20.756: E/AndroidRuntime(353): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.ian.counter/com.ian.counter.CounterActivity}: java.lang.NullPointerException
12-28 16:59:20.756: E/AndroidRuntime(353): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1569)
12-28 16:59:20.756: E/AndroidRuntime(353): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
12-28 16:59:20.756: E/AndroidRuntime(353): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
12-28 16:59:20.756: E/AndroidRuntime(353): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
12-28 16:59:20.756: E/AndroidRuntime(353): at android.os.Handler.dispatchMessage(Handler.java:99)
12-28 16:59:20.756: E/AndroidRuntime(353): at android.os.Looper.loop(Looper.java:123)
12-28 16:59:20.756: E/AndroidRuntime(353): at android.app.ActivityThread.main(ActivityThread.java:3683)
12-28 16:59:20.756: E/AndroidRuntime(353): at java.lang.reflect.Method.invokeNative(Native Method)
12-28 16:59:20.756: E/AndroidRuntime(353): at java.lang.reflect.Method.invoke(Method.java:507)
12-28 16:59:20.756: E/AndroidRuntime(353): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
12-28 16:59:20.756: E/AndroidRuntime(353): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
12-28 16:59:20.756: E/AndroidRuntime(353): at dalvik.system.NativeStart.main(Native Method)
12-28 16:59:20.756: E/AndroidRuntime(353): Caused by: java.lang.NullPointerException
12-28 16:59:20.756: E/AndroidRuntime(353): at android.app.Activity.findViewById(Activity.java:1647)
12-28 16:59:20.756: E/AndroidRuntime(353): at com.ian.counter.CounterActivity.<init>(CounterActivity.java:10)
12-28 16:59:20.756: E/AndroidRuntime(353): at java.lang.Class.newInstanceImpl(Native Method)
12-28 16:59:20.756: E/AndroidRuntime(353): at java.lang.Class.newInstance(Class.java:1409)
12-28 16:59:20.756: E/AndroidRuntime(353): at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
12-28 16:59:20.756: E/AndroidRuntime(353): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1561)
任何帮助表示赞赏。
最佳答案
您试图在设置布局之前设置textView1
变量。您需要将其定义为变量,然后在调用onCreate()
后在setContentView()
中进行分配。像这样:
package com.ian.counter;
import android.app.Activity;
import android.widget.TextView;
import android.os.Bundle;
import android.widget.Toast;
public class CounterActivity extends Activity {
/** Called when the activity is first created. */
TextView textView1;
int count = 0;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
textView1 = (TextView) this.findViewById(R.id.textView1);
}
public void Count(){
count ++;
textView1.setText(Integer.toString(count));
}
}
只要复制并粘贴上面的内容,就可以了。