Java 尝试调用虚拟方法时遇到错误';setAdapter(RecyclerView$Adapter)和#x27;关于Android Studio中的空对象引用
在运行代码时,我遇到了在空对象引用上“尝试调用虚拟方法”void androidx.recyclerview.widget.recyclerview.setAdapter(androidx.recyclerview.widget.recyclerview$Adapter)”的问题。我已经寻找过类似的解决方案,但似乎并没有解决我的错误 我应该如何修改代码 这是我的MainActivity.java代码:Java 尝试调用虚拟方法时遇到错误';setAdapter(RecyclerView$Adapter)和#x27;关于Android Studio中的空对象引用,java,android,android-recyclerview,Java,Android,Android Recyclerview,在运行代码时,我遇到了在空对象引用上“尝试调用虚拟方法”void androidx.recyclerview.widget.recyclerview.setAdapter(androidx.recyclerview.widget.recyclerview$Adapter)”的问题。我已经寻找过类似的解决方案,但似乎并没有解决我的错误 我应该如何修改代码 这是我的MainActivity.java代码: package endlesstaste; import android.os.Bundle
package endlesstaste;
import android.os.Bundle;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.android.material.snackbar.Snackbar;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import java.util.LinkedList;
public class MainActivity extends AppCompatActivity {
private final LinkedList<String> mImagePathList = new LinkedList<>();
private String mDrawableFilePath =
"android.resource://endlesstaste/drawable/";
private RecyclerView mRecyclerView;
ImageListAdapter mAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
for (int i = 1; i <= 5; i++) {
mImagePathList.addLast(mDrawableFilePath + "image" + i);
}
// Get a handle to the RecyclerView.
mRecyclerView = findViewById(R.id.recyclerview);
// Create an adapter and supply the data to be displayed.
mAdapter = new ImageListAdapter(this, mImagePathList);
// Connect the adapter with the RecyclerView.
mRecyclerView.setAdapter(mAdapter);
// Give the RecyclerView a default layout manager.
mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
}
@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);
}
}
package endlesstaste;
import android.os.Bundle;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.android.material.snackbar.Snackbar;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import java.util.LinkedList;
public class MainActivity extends AppCompatActivity {
private final LinkedList<String> mImagePathList = new LinkedList<>();
private String mDrawableFilePath =
"android.resource://endlesstaste/drawable/";
private RecyclerView mRecyclerView;
ImageListAdapter mAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
for (int i = 1; i <= 5; i++) {
mImagePathList.addLast(mDrawableFilePath + "image" + i);
}
// Get a handle to the RecyclerView.
mRecyclerView = findViewById(R.id.recyclerview);
// Create an adapter and supply the data to be displayed.
mAdapter = new ImageListAdapter(this, mImagePathList);
// Connect the adapter with the RecyclerView.
mRecyclerView.setAdapter(mAdapter);
// Give the RecyclerView a default layout manager.
mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
}
@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);
}
}
package endlesstate;
导入android.os.Bundle;
导入com.google.android.material.floatingactionbutton.floatingactionbutton;
导入com.google.android.material.snackbar.snackbar;
导入androidx.appcompat.app.appcompat活动;
导入androidx.appcompat.widget.Toolbar;
导入androidx.recyclerview.widget.LinearLayoutManager;
导入androidx.recyclerview.widget.recyclerview;
导入android.view.view;
导入android.view.Menu;
导入android.view.MenuItem;
导入java.util.LinkedList;
公共类MainActivity扩展了AppCompatActivity{
private final LinkedList mImagePathList=新建LinkedList();
私有字符串mDrawableFilePath=
“安卓。resource://endlesstaste/drawable/";
私人回收视图mRecyclerView;
ImageListAdapterMadapter;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
对于(inti=1;i您不能调用
mRecyclerView = findViewById(R.id.recyclerview);
打电话之前
setContentView(R.layout.activity_main);
执行此操作时,对findViewById
的调用将返回null。在开始获取视图之前,将setContentView
(和super.onCreate
移动到onCreate
的开始处。您不能调用
mRecyclerView = findViewById(R.id.recyclerview);
打电话之前
setContentView(R.layout.activity_main);
执行此操作时,对findViewById
的调用将返回null。在开始获取视图之前,将setContentView
(和super.onCreate
移动到onCreate
的开始处。是否尝试过使用super.onCreate(savedInstanceState);setContentView(R.layou.activity\u main);作为onCreate的第一行您是否尝试过使用super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);作为onCreate的第一行伟大!如果答案解决了您的问题,请确保接受答案。伟大!如果答案解决了您的问题,请确保接受答案。