在我修改这些点击侦听器之后出现了这个错误
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: FATAL EXCEPTION: main
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: Process: com.thebubble.animationstransitions, PID: 14626
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.thebubble.animationstransitions/com.thebubble.animationstransitions.MainActivity}: java.lang.NullPointerException
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2343)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2395)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at android.app.ActivityThread.access$800(ActivityThread.java:154)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1326)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:110)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at android.os.Looper.loop(Looper.java:193)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:5315)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at java.lang.reflect.Method.invokeNative(Native Method)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at java.lang.reflect.Method.invoke(Method.java:515)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:836)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:652)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at dalvik.system.NativeStart.main(Native Method)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: Caused by: java.lang.NullPointerException
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at com.thebubble.animationstransitions.MainActivity.onCreate(MainActivity.java:28)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at android.app.Activity.performCreate(Activity.java:5283)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1088)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2307)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2395)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at android.app.ActivityThread.access$800(ActivityThread.java:154)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1326)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:110)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at android.os.Looper.loop(Looper.java:193)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:5315)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at java.lang.reflect.Method.invokeNative(Native Method)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at java.lang.reflect.Method.invoke(Method.java:515)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:836)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:652)
10-14 12:22:47.811 14626-14626/? E/AndroidRuntime: at dalvik.system.NativeStart.main(Native Method)
10-14 12:22:47.827 14626-14626/? I/Process: Sending signal. PID: 14626 SIG: 9
MainActivity.java代码
package com.thebubble.animationstransitions;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.transition.TransitionManager;
import android.view.Menu;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.RelativeLayout;
public class MainActivity extends ActionBarActivity {
int touchCount;
Button theButton;
ViewGroup mainView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
theButton.setOnClickListener(
new Button.OnClickListener(){
boolean bull = true;
public void onClick(View v){
moveButton(bull);
if(bull==true){
bull = false;
}else{
bull =true;
}
}
}
);
}
public void moveButton(boolean decision) {
if (decision) {
View theButton = findViewById(R.id.theButton);
TransitionManager.beginDelayedTransition(mainView);
//Changes the position of the button
RelativeLayout.LayoutParams positionRules = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);
positionRules.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM, RelativeLayout.TRUE);
positionRules.addRule(RelativeLayout.ALIGN_PARENT_RIGHT, RelativeLayout.TRUE);
theButton.setLayoutParams(positionRules);
ViewGroup.LayoutParams sizeRules = theButton.getLayoutParams();
sizeRules.width = 450;
sizeRules.height = 450;
theButton.setLayoutParams(sizeRules);
} else {
View theButton = findViewById(R.id.theButton);
TransitionManager.beginDelayedTransition(mainView);
//Changes the position of the button
RelativeLayout.LayoutParams positionRules = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);
positionRules.addRule(RelativeLayout.ALIGN_PARENT_TOP, RelativeLayout.TRUE);
positionRules.addRule(RelativeLayout.ALIGN_PARENT_LEFT, RelativeLayout.TRUE);
theButton.setLayoutParams(positionRules);
ViewGroup.LayoutParams sizeRules = theButton.getLayoutParams();
sizeRules.width = 150;
sizeRules.height = 50;
theButton.setLayoutParams(sizeRules);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
它只是一个简单的代码，可以更改按钮的位置和大小，并创建一个简单的过渡 我是初学者，所以我需要更详细的答案
答案 0 :(得分：2)
您忘记初始化按钮theButton。
插入：
theButton = (Button) findViewById(R.id.yourButtonId);
在设置点击监听器之前。