See the usage of the code above:
import com.google.common.base.Objects; public class ObjectsLearn { private Integer id; private String name; private String address; public ObjectsLearn(Integer id, String name, String address) { super(); this.id = id; this.name = name; this.address = address; } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getAddress() { return address; } public void setAddress(String address) { this.address = address; } @Override public String toString() { //return "ObjectsLearn [id=" + id + ", name=" + name + ", address=" + address + "]"; return Objects.toStringHelper(this).omitNullValues().add("id", id).add("name", name).add("address", address).toString(); } @Override public int hashCode() { return Objects.hashCode(id,name,address); } public static void main(String[] args) { ObjectsLearn learn = new ObjectsLearn(1, "test", "天上"); System.out.println(learn); } }
Take a look at the source code record of Objects.toStringHelper(this).omitNullValues().add("id", id).add("name", name).add("address", address).toString() Next:
Objects This piece of code is implemented in a linked list structure:
public static final class ToStringHelper { private final String className; private final ValueHolder holderHead = new ValueHolder(); private ValueHolder holderTail = holderHead; private boolean omitNullValues = false;
Defines the head holderHead of a linked list;
private ValueHolder addHolder() {
ValueHolder valueHolder = new ValueHolder();
holderTail = holderTail.next = valueHolder;
return valueHolder;
}
This piece of code points to the next node;
private ToStringHelper addHolder(String name, @ Nullable Object value) {
ValueHolder valueHolder = addHolder();
valueHolder.value = value;
valueHolder.name = checkNotNull(name);
return this;
}
This piece of code first calls addHolder to point to the next node, and then assigns a value to the next node.