这段代码有什么错误?当我运行程序时,它说“应用程序 buttonProj(进程 com.example.buttonproj)已意外停止。请重试”我只是尝试创建一个添加和减去按钮,用户可以单击它来增加或减少数字 i .
package com.example.buttonproj;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends Activity {
int counter;
Button add, sub;
TextView display;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
counter = 0;
add = (Button) findViewById(R.id.bAdd);
sub = (Button) findViewById(R.id.bSub);
display = (TextView) findViewById(R.id.textView1);
add.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
counter +=1;
display.setText(counter);
}
});
sub.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
counter--;
display.setText(counter);
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}