Java TextView不显示日志
好吧,我是android新手,我一直在学习一门课程,但有些事情我不明白 这是Java TextView不显示日志,java,android,Java,Android,好吧,我是android新手,我一直在学习一门课程,但有些事情我不明白 这是LifeCycleT活动 package com.example.killtheviolence.myapplication; import android.app.Activity; import android.os.Bundle; import android.util.Log; import android.widget.TextView; public class LifeCycleT extends Ac
LifeCycleT
活动
package com.example.killtheviolence.myapplication;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
public class LifeCycleT extends Activity {
StringBuilder builde = new StringBuilder();
TextView textview;
private void log(String text) {
Log.d("LifeCycleT", text);
builde.append( builde.toString() );
builde.append("\n");
textview.setText(builde.toString());
}
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
TextView textview = new TextView(this);
textview.setText(builde.toString());
setContentView(textview);
}
protected void onResume() {
super.onResume();
log("resume");
}
protected void onPause() {
super.onPause();
log("paused");
if(isFinishing()) {
log("death");
}
}
}
这是从哪里来的?从列表视图
package com.example.killtheviolence.myapplication;
import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListAdapter;
import android.widget.ListView;
public class MainActivity extends ListActivity {
String prueva[] = {"LifeCycleT","item2","item3","item4",
"item5 ", "item6 "};
public void onCreate(Bundle savedInstanceSate){
super.onCreate(savedInstanceSate);
setListAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, prueva));
}
@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
super.onListItemClick(l, v, position, id);
String gate = prueva[position];
try {
Class<?> inst;
inst = Class.forName("com.example.killtheviolence.myapplication." + gate);
Intent intent = new Intent(this, inst);
startActivity(intent);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
}
为什么我要创建两个
TextView
实例?为什么我要设置两次?为什么它在文本视图中不显示任何内容?(仅当我在setText
的参数中编写“string”
时显示)修复onCreate
以将字段参数设置为非本地参数:
@Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
textview = new TextView(this); // << This used to be a local var, thats why NPE
textview.setText(builde.toString());
setContentView(textview);
}
还请注意,我更改了您的StringBuilder
,将作为参数传递的文本附加到log
方法中问题不在于Android,而在于您使用StringBuilder
的方式。我想在开始开发Android应用程序之前,你应该再复习一下基础知识。为什么你要手工制作TextView类而不是膨胀布局?因为这是我的第一个Android应用程序,我不知道你在说什么,我只知道java。。。我是在诅咒吗?)
@Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
textview = new TextView(this); // << This used to be a local var, thats why NPE
textview.setText(builde.toString());
setContentView(textview);
}
private void log(String text) {
Log.d("LifeCycleT", text);
builde.append("\n");
builde.append(text);
textview.setText(builde.toString());
}